Continuous Press

Abstract

A continuous press is disclosed for simultaneously pressing and conveying a workpiece, such as the laminations for making plywood, through the press is a continuous manner. The continuous press comprises upper and lower platens upon which are mounted opposed sets of presser-conveyor rails, which are spaced apart to receive a workpiece therebetween. The presser-conveyor rails are mounted upon the respective platens by means of plural cams (circular eccentrics). Each set of rails drives a caterpillar belt and preferably a sheet belt which encircles the platen supporting that set of rails. The workpiece is interposed between the sheet belts. The rails in each set are divided into plural groups and the supporting eccentrics impart orbital motion to the rails in a polyphase arrangement, i.e, the motion of each group of rails is phase displaced from the motion of each group of rails. The two opposed sets of rails are actuated synchronously with the corresponding groups of rails and the two sets being 180.degree. out of phase with each other.

Description

FIELD OF THE INVENTION

This invention relates to apparatus for simultaneously pressing and conveying a workpiece; more particularly the invention relates to apparatus for continuous pressing of workpiece material while the workpiece material is continuously conveyed through the apparatus.

BACKGROUND OF THE INVENTION

The need for a continuous press capable of applying uniform and high pressure continuously to a workpiece while the workpiece is conveyed through the press has long been recognized. There are numerous applications, such as the manufacture of laminated board or composition particle board, which is performed by a batch-process, even though a continuous process would be much more efficient if equipment were available. The prior art reflects a considerable effort to develop a continuous press capable of applying high pressure uniformly over the surface of a workpiece; however, it appears that heretofore the need for the continuous press has not been met.

Among the major problems in devising a high pressure continuous press is the problem of obtaining uniform pressure over the area of the workpiece and the problem of producing continuous motion of the workpiece through the press under high pressure without overloading the bearings which support the moving press members. Where anti-friction bearings of the rolling type have been used, the small available bearing area results in high stresses and bearing failure and if slide bearings are utilized to take advantage of large bearing area, the sliding friction and resulting heat generation are excessive and the device is impractical.

One type of prior art continuous press utilizes a pair of oppositely rotating chains of platens which are spaced apart to receive a workpiece therebetween. The platens are aligned in the direction of movement and are driven continuously over guide rollers or sprockets. Pressure is applied by hydraulic means to compress the workpiece between the opposed chains of platens and an anti-friction roller belt is provided on the backside of each of the chain of platens to provide a roller type bearing for the chains of platens. Such apparatus is disclosed in the Dyke Pat. No. 2,071,999 and also in the Lambert et al. Pat. No. 2,490,819. A difficulty with this type of continuous press arises from the use of roller belts disposed between plane surfaces as the bearing members for supporting the continuously moving and heavily loaded platens which engage the workpiece.

Another type of continuous press known in the prior art utilizes two oppositely disposed sets of parallel bars with the bar of each set extending in the direction of travel of the workpiece through the press. The workpiece is compressed between a pair of bars, one from each set, during a forward stroke of the pair of bars and then is compressed between a second pair of bars, one from each set, during a forward stroke of the second pair of bars. The bars of the first pair are caused to separate and relieve pressure on the workpiece and to make a return stroke during the forward stroke of the second pair. Similarly, the second pair of bars makes a return stroke during the forward stroke of the first pair. Apparatus of this type is set forth in the Maurer Pat. No. 2,340,607 wherein the bars are driven in the forward stroke by friction drive rollers and are released by the rollers at a flat spot thereon for a return stroke under the influence of a retracting spring. Another continuous press of this type is disclosed in the Maurer Pat. No. 2,289,022 wherein selected bars from the upper and lower set of bars are moved toward each other for compressing the workpiece therebetween by means of a cam and follower arrangement and the same bars are moved in a forward and return stroke on a common carriage which is actuated by a separate cam and follower arrangement. A difficulty with the apparatus of the former Maurer patent is the use of the friction drive for advancing the bars; a difficulty with the apparatus of the latter Maurer patent is that it requires separate drive means for closing the press bars and separate drive means for the feed or advance of the press bars. Another prior art apparatus using the reciprocating bar arrangement is shown in the Guyer Pat. No. 3,577,304. In the apparatus of this patent, a pair of opposed lifter bars are spaced apart to accept the workpiece therebetween and are mounted upon oppositely rotating eccentrics. Upon each rotation of the eccentrics the lifter bars successively compress the workpiece therebetween and impart a forward motion to it; at the end of the forward stroke the lifter bars open and a pair of holding bars are closed thereagainst by spring pressure to maintain compression of the workpiece in a dwell-condition while the lifter bars make a return stroke. A disadvantage of this arrangement is that the workpiece is intermittently advanced through the press and the pressure on the workpiece is alternately applied by the eccentric-actuated lifter bars and the spring-actuated holding bars.

Another type of continuous press utilizes sliding friction to obtain a large bearing area for support of the moving press members. In this type of apparatus a pair of endless belts are disposed opposite each other and each is mounted on suitable drive rollers. The portions of the endless belts which are disposed in opposition and which receive the workpiece therebetween are respectively backed by rigid plates which in turn are supported by hydraulic plungers. To reduce the sliding friction the sheet of material having a low coefficient of friction is interposed between the moving belts and the respective backing plates. A continuous press of this type is shown in the Pfeiffer Pat. No. 3,680,476.

SUMMARY OF THE INVENTION

According to this invention there is provided a continuous press which is capable of applying high pressure to a workpiece while the workpiece is continuously conveyed through the press. This is accomplished by opposed platens each of which carries a set of rails which face in a direction toward each other and which are spaced apart to accept the workpiece therebetween. The rails of each set are mounted on the respective platens with two rails being mounted upon cams rotatably supported on the platen. Drive means are provided for rotating the cams to impart orbital motion to the rails; the cams being rotated in predetermined phase relationship so that a pair of rails, one from each set, move simultaneously in the respective orbital paths toward the workpiece to press it therebetween and also move in the feeding direction to advance the workpiece through the press. Additionally, the drive means imparts orbital motion to a second pair of rails in such phase relation with each other and the first pair of rails so that the second pair are simultaneously moving away from the workpiece and opposite the feeding direction while the rails of the first pair are in their pressing-forward stroke. In other words, a first pair of rails, one from each set, makes a press and advance stroke while another pair of rails, one from each set, makes a release and return stroke. Accordingly, the workpiece is continuously pressed and continuously advances through the press.

Further, in accordance with the invention, the pressure applied to the workpiece is maintained substantially constant as a function of time when the workpiece is fed through the press. This is accomplished by using an hydraulic force applying means for supporting one of the platens. The other platen may be fixedly mounted to the frame of the press. The hydraulic force applying means is provided with an hydraulic accumulator which serves to maintain a constant hydraulic pressure in the force applying means despite the small cyclical variation in the spacing between pairs of rails during the press-advance stroke of each pair. Further, according to the invention, the pressure applied to the workpiece is maintained at a uniform value over the surface of the workpiece. This is accomplished by means of a "caterpillar" belt or endless belt of crossbars. Such a caterpillar belt encircles the first platen and extends over the rails thereon with the crossbars spanning the rails, so that the force exerted by one or more rails toward the workpiece is applied through the bars to the workpiece. Similarly, such a belt encircles the other platen and coacts with the rails thereof in the same manner. Additionally, it is preferred to provide an endless sheet belt encircling the caterpillar belt on the first platen and an endless sheet belt encircling the caterpillar belt on the second platen, in order to present an uninterrupted flat surface to both sides of the workpiece.

Also, according to the invention, a continuous press is provided which has an exceedingly large load or pressure capacity. This is accomplished by providing a large bearing area by mounting the rails directly on the motion imparting cams or eccentrics, so that each mounting constitutes a journal bearing. This bearing area is multiplied by using multiple cams for each rail. Also the cam shaft bearing area is maximized by spacing the rails and disposing a cam shaft bearing between rails. In order to avoid gaps between the rails each rail is preferably of T-shaped cross-section, i.e., the head of the rail is wider than the web.

Further, in accordance with the invention, the variation in torque requirements for driving the motion imparting cams is minimized. This is accomplished by means of a polyphase arrangement of the cams and rails. In one embodiment the rails of each set are divided into two groups with all rails in the same group being moved in their respective orbital paths in phase with each other. The motion of the first group of rails is 180.degree. out of phase with the motion of the other group of rails. This embodiment with two groups of rails in each set, and with the motion of the two groups of rails being of opposite phase, is referred hereinafter to a "two-phase" arrangement. In another preferred polyphase arrangement the rails of each set are divided into three groups and the orbital motions of the three groups are displaced in phase from each other by 120.degree.. In this arrangement which will be termed herein a "three-phase" arrangement, the motion of the second group of rails lags the motion of the first group of rails by 120.degree. and the motion of the third group of rails lags the motion of the second group of rails by 120.degree.. The invention contemplates, in general, a polyphase arrangement of any desired number of phases wherein the phase angle between successive phases is equal to 360.degree. divided by the number of phases or groups of rails.

Further, in accordance with the invention, the continuous press is adapted to provide variable feedrate without changing the pressure exerted by the press. This is accomplished by use of a common drive for all of the cams which in turn actuate the rails through both the pressure and advance strokes. Further, the synchronism of all cams is assured by providing a gear drive from the common drive means.

DETAILED DESCRIPTION

A more complete understanding of this invention may be obtained from the detailed description which follows, taken with the accompanying drawings in which:

FIG. 1 is a side elevation view of the continuous press of this invention;

FIG. 2 is a view taken on lines 2--2 of FIG. 1;

FIG. 3 is a view taken on lines 3--3 of FIG. 2;

FIG. 4 is a view taken on lines 4--4 of FIG. 1;

FIG. 5 shows a detail of construction;

FIG. 6 shows a temperature control system; and

FIGS. 7 and 8 show a modification.

Referring now to the drawings, there is shown an illustrative embodiment of the invention in a continuous press which is adapted for simultaneously pressing and conveying a workpiece on a continuous through-put basis while maintaining the workpiece at a desired temperature during its travel through the press. It will be appreciated as the description proceeds that the invention may be embodied in a continuous press for a wide variety of applications. Although the inventive apparatus is capable of producing extremely high pressures on the workpiece, it may also be used in applications where low pressure is required; further, whatever the pressure requirement may be, the continuous press also provides dimensional control for the workpiece. Additionally, the continuous press is adapted to provide heat treatment or curing of the workpiece by temperature control for a predetermined period during the travel of the workpiece through the press. Typical applications of the continuous press include the manufacture of large plywood sheets on a continuous basis where the workpiece is relatively thick and wide and moderately high pressure is required, together with elevated temperature for curing. A typical application for a small workpiece is that of manufacturing phenolic circuit boards which require extremely high pressures and precise thickness control.

As shown in FIG. 1, the continuous press comprises a stationary base 6 which supports an upper press member 8 and a lower press member 12. The upper press member is held in fixed position relative to the base member 6, while the lower press member is supported upon a vertically movable platform 16. An upper platen 10 carries an upper set of presser-conveyor rails 18 and a lower platen 14 carries a lower set of presserconveyor rails 20. The upper and lower sets of rails are disposed in face to face relationship and are spaced apart to accept a workpiece 22 therebetween. It is noted that the workpiece 22 takes the form of a continuous thin and wide board, such as plywood, which is moved continuously through the press in the direction indicated by the arrow.

Referring further to FIG. 1, the upper press member 8 is supported on the base 6 by means of columns or corner posts 24 and horizontal beams 26 supported on the posts. The platen 10 is supported from the beams 26 by means of plural frame members 28 which are partially concealed by the cover plates 30 and 32. A shield member 34, partially broken away in FIG. 1, is mounted on the platen 10 outboard of the set of rails 18 on the near side of the press as viewed in FIG. 1.

The upper press member 8 also includes an endless caterpillar belt 36 which encircles the upper platen 10 and is supported upon a pair of rollers 38 and 40, which in turn are supported on bearing plates 42 and 44, which depend from the beams 26. The caterpillar belt 36 comprises a multiplicity of rigid bar links, each of which extends transversely of the press and spans the upper set of rails 18 in engagement therewith. The bar links 46 are disposed edge-to-edge and each is provided with a tapered cross-section to provide clearance from the adjacent bar links in passing over the rollers 38 and 40. Each bar link is secured to the adjacent one by means of a coil spring 48.sup.1 which draws the adjacent links together to provide a substantially uninterrupted surface. (See FIG. 3 which shows the lower caterpillar belt of the same construction).

Referring further to the upper press member 8, an endless sheet belt 50 is disposed over the caterpillar belt 36 to provide a continuous and smooth facing to be presented to the workpiece. The sheet belt 50 is suitably constructed of stainless steel having a smooth and polished outer surface which engages the upper surface of the workpiece. The caterpillar belt 36, and consequently the sheet belt 50, are driven on the rollers 38 and 40 by the upper set of presser-conveyor bars 18 which, along with the associated actuating mechanism, will be described subsequently.

Referring further to FIG. 1, the lower press member 12 will now be described. This press member, in addition to the lower platen 14, and the lower set of presser-conveyor bars 20 comprises an endless caterpillar belt or link belt 52. The caterpillar belt 52 encircles the lower platen 14 and is supported upon a pair of rollers 54 and 56. The rollers are supported upon bearing plates 58 and 60 which are mounted upon the platform 16. The lower platen 14 is fixedly mounted upon the platform 16 by frame members which are concealed by the cover plate 62. The caterpillar belt 52 is of the same construction as the previously described caterpillar belt 36 and has its surface disposed in engagement with the lower set of presser-conveyor bars 20. An endless sheet belt 64 encircles the caterpillar belt 52 and is supported upon a pair of rollers 66 and 68. The rollers 66 and 68 are mounted upon bearing plates 70 and 72 respectively, which in turn are mounted upon the platform 16. The endless sheet belt 64 is of the same construction as the sheet belt 50 described above, and presents a smooth polished surface to the lower surface of the workpiece 22. The sheet belt 64 is longer than the sheet belt 50 and is supported on the separate rollers 66 and 68 to provide a lower workpiece support surface at the input and output ends of the press to facilitate loading and unloading.

The spacing of the press members will, of course, determine the opening or vertical dimension of the press throat which is defined by the spacing between the sheet belt 50 and the sheet belt 64 at the opposed sets of rails 18 and 20. The throat or press opening is preset in accordance with the desired dimension of the workpiece and the setting is accomplished by raising or lowering the platform 16. For this purpose the platform 16 is mounted upon the base 6 by plural hydraulic actuators or jacks 74, 76 and 78. The hydraulic actuators are energized with hydraulic fluid from a pump 80 which is driven by an electric motor 82. In order to supply substantially constant pressure to the actuators despite minor fluctuations in loading, an hydraulic accumulator 84, suitably of the bladder type, is connected serially in the supply line 86 to the actuators which are connected in parallel. The hydraulic actuators are provided with double-acting pistons and a return line is connected with the pump.

Referring now to FIGS. 2, 3 and 4, the upper and lower platens 10 and 14 and the upper and lower sets of rails 18 and 20 and the associated actuating mechanism will now be described. The lower platen 14, suitably in the form of a flat plate, is fixedly mounted upon the platform 16 by frame members as previously mentioned. The platen 14 supports the lower set of presser-conveyor rails 20. All of the rails in the lower set are of the same construction, suitably of steel, and have a T-shaped cross-section. Each of the rails 20 has a web 90 which is narrower than the head 92 of the rail. Additionally, each of the rails is provided with a fluid passage 94 in the head of the rail for purposes which will be described later. As shown in FIG. 3, each of the rails 20 is provided with multiple axially spaced bearing surfaces 96. These bearing surfaces are suitably provided by slots formed in the lower edge of the web 90 of the rail; alternatively, however, the surfaces 96 could be formed by holes drilled through the web of the rail and, if desired, provided with suitable bearing inserts.

In order to support the individual rails 20 of the lower set of rails on the lower platen 14 and to impart orbital motion to the individual rails, plural cams are interposed between each rail and the platen. In the embodiment of FIGS. 2, 3 and 4, a two-phase cam arrangement is employed. In order to impart two-phase orbital motion to the presser-conveyor rails the set of rails is divided into two groups with each rail in the first group designated by the reference character 20 and each rail in the second group designated by the reference charater 20'. Each rail is supported upon plural cams with the first group of rails 20 being supported upon cams 98 and the second group of rails 20' being supported upon a second group of cams 98'. All of the cams 98 and 98' which are axially aligned, such as those depicted in FIG. 2, will be referred to as a set of cams and are mounted in fixed angular relation upon a cam shaft 100 for rotation therewith. The set of cams depicted in FIG. 2 are mounted upon the cam shaft 100, while additional set of cams 98 and 98' are mounted upon additional cam shafts 100a, 100b, 100c, 100d, 100e, and so on, depending upon the desired number of sets of cams (see FIG. 4). The cam shaft 100 is supported on the platen 14 by a pair of main journal bearings 101 and 103 and by a plurality of intermediate journal bearings 105. It is noted that an intermediate journal bearing 105 may be disposed between each pair of rails to provide an extensive bearing area for the cam shaft.

As stated previously, the cams 98 and 98' are preferably of the same configuration, namely, circular eccentric of the same size and of the same eccentricity, i.e. the same throw. As can be seen from FIGS. 2 and 4, the cams 98 are 180.degree. out of phase with the cams 98', i.e., they are displaced by a predetermined phase angle of 180.degree.. Accordingly, in the positions shown in FIG. 2, the rails 20 are in their most extended position in which the head of the rail is displaced a maximum distance from the center of the cam shaft 100 or the platen 14. At this given angular position of the cam shaft 100 the rails 98' are in their most retracted position so that the rail head is at its minimum distance from the center line of the cam shaft or the platen 14. The difference between the maximum and minimum displacements of the head of the rail is referred to herein as the throw of the eccentric and is of course equal to the displacement of the center line of the eccentric itself from the center line of the cam shaft. It is noted that rotation of the crankshaft 100 through an angular displacement of 180.degree. causes the rails 98 and 98' to reverse the positions shown in FIG. 2. Rotation of the cam shaft 100 imparts orbital motion to each of the rails 98 and 98' and, of course, a circular orbital path is described by any given point on a rail for each revolution of the cam shaft. It is further noted with reference to FIG. 2, taking the angular position of the cam shaft 100, as shown, to be the reference position, that 90.degree. rotation of the cam shaft either clockwise to counterclockwise will change the positions of both rails 98 and 98' so that they are at equal displacements from the center line of the cam shaft, i.e., the working faces 96 of the rails are in alignment with each other. This relative position of the rails 98 and 98' may be referred to as the transfer position because it is at this point in rotation of the cam shaft that the rails 20 disengage the caterpillar belt 52 and the rails 20' engage the caterpillar belt 52, or vice versa, and consequently the work applied to the workpiece is shifted from one set of rails to the other. Further examination of the set of rails 20 and 20' in FIGS. 2 will aid in further understanding of the pressure and motion imparted by the presser-conveyor rails to the workpiece. With the cam shaft 100 rotating in a clockwise direction as viewed from the righthand end, the rail 20 will be moving forward (direction of the arrow in FIG. 1 and into the paper in FIG. 2), immediately after it passes its top dead center position in the rotation of the cam shaft 100. This portion of the orbital path of the rail 20 carries the caterpillar belt 52 in the forward direction and hence advances the workpiece 22 through the press. At the same time the rail 20' is disengaged from the caterpillar belt 52 and immediately after passing its bottom dead center position this rail is moving rearwardly (out of the paper in FIG. 2) and upwardly. Accordingly the rotation of the cam shaft 100 in the clockwise direction as viewed from the righthand end in FIG. 2, continuously advances the workpiece through the press in the feeding direction of the arrow shown in FIG. 1. The amount of advancement of the workpiece for each revolution of the cam shaft depends upon the throw of the cams or eccentrics and the forward motion of the workpiece is substantially uniform.

Referring further to FIG. 2 the upper platen 10, the set of rails 18 and the associated actuating mechanism will now be described. The assembly is basically the same as that just described with reference to the lower platen 14 and the rails 20 and 20' and accordingly only brief description is required. The set of rails 18, for convenience of description, is divided into a first group including rails 18 and a second group including rails 18'. Each individual rail is of the same construction as the rails 20 in the lower set. Each rail is similarly mounted upon plural cams as illustrated in FIG. 3 with respect to rails 20. Each rail 18 is supported upon a cam (circular eccentric) 104 and each rail 18' is supported upon a cam (circular eccentric) 104'. The set of cams comprising cams 104 and 104' which are axially aligned with each other are mounted upon a cam shaft 106 for rotation therewith. The cam shaft 106 is supported on the platen 10 by a pair of main journal bearings 107 and 108 and by a plurality of intermediate journal bearings 109. It is noted that an intermediate journal bearing 109 may be disposed between each pair of rails to provide an extensive bearing area for the cam shaft.

Referring further to the cams 104 and 104', as shown in FIG. 2, these cams are angularly displaced from each other on the cam shaft by a phase angle of 180.degree.. Further, a phase relation is pre-established between the first group of cams 104 and the first group of cams 98 and hence between the first group of rails 18 and the first group of rails 20. In this predetermined phase relationship, as shown in FIG. 2, the motion of the rail 18 is 180.degree. out of phase with the motion of the rail 20. Similarly, the motion of the rail 18' is 180.degree. out of phase with the motion of the rail 20'. In other words, when rail 20 is in its top dead center position the rail 18 is in its bottom dead center position; also as shown, the rail 20' is in its bottom dead center position while the rail 18' is in its top dead center position.

The coaction of the set of rails 20 and 20' with the set of rails 18 and 18' will now be appreciated. In order to advance the workpiece 22 through the press the cam shaft 100 is rotated in a clockwise direction as viewed from the righthand end in FIG. 2 and the cam shaft 106 is rotated in a counter clockwise direction as viewed from the righthand end in FIG. 2. During each revolution of the cam shafts 100 and 106 the presser-conveyor rails 18 and 20 will move toward each other and in a forward direction, clamping the workpiece therebetween and advancing it through the press. At the same point where the rails 18 and 20 release the workpiece the rails 18' and 20' will engage the workpiece in their motion toward each other and in the forward direction, i.e., the transfer point occurs where the work shifts from rails 18 and 20 to rails 18' and 20'. It is observed that in the circular orbital motion of the rails 18 and 20 the components of motion toward and away from each other is a harmonic motion with cyclical variation in the spacing between the rails 18 and 20 at a frequency corresponding to the speed of rotation of the cam shafts. Further, it is noted that when the rail 20 is at its top dead center and the rail 18 is at its bottom dead center, the rails are at minimum spacing and this minimum spacing is less than the spacing at the transfer point when the rails 18' and 20' engage the workpiece. Similarly, before the next transfer point occurs the rails 18' and 20' will have passed through their point of minimum spacing. As a consequence cyclical variation in the spacing between the rails 18 and 20 and the out-of-phase cyclical variations in the spacing between the rails 18' and 20', the pressure transmitted to the workpiece through the caterpillar belts 36 and 52 is of an oscillatory character of very small amplitude and having a frequency corresponding to twice the rotational speed of the cam shafts. This cyclical variation in pressure is eliminated by the action of the hydraulic accumulator 80 so that the pressure applied to the workpiece is substantially constant in value.

In order to drive the cam shafts in synchronism and to maintain proper phase relationship a drive train is provided as shown in FIGS. 2 and 4. A single prime mover (not shown) is coupled to the input shaft 110 and the prime mover is preferably of variable speed type so that the feedrate of the press may be adjusted. The input shaft 110 is coupled through beveled gears 112 and 114 to a splined counter shaft 116 which is suitably journalled in the upper and lower platens 10 and 14. The splined shaft arrangement accommodates the change in spacing between the platens when the press is adjusted for different size workpieces. The countershaft 116 is coupled through beveled gears 118 and 120 to a stub shaft 122 which is mounted in a bearing plate 124. A pinion gear 126 on the stub shaft 122 meshes on one side with a driven gear 128 mounted on the cam shaft 100. The pinion gear 126 meshes on the other side with a driven gear 130 which is mounted on the cam shaft 100e.

In a similar manner, rotational drive is imparted to the plural cam shafts mounted on the upper platen 10. This drive train is shown in part on FIG. 2 with the counter shaft 116 connected through beveled gears 134 and 136 to a stub shaft 138, which is mounted on a bearing plate 140. The stub shaft is connected to a pinion gear and a pair of driven gears on opposite sides thereof in the same manner as the pinion gear 126 is connected to the driven gears 128 and 130, as shown in FIG. 4. Referring to FIG. 2, the aforementioned pinion gear meshes with a driven gear 142 (which is one of the aforementioned driven gears), which is drivingly connected to the cam shaft 106. As previously explained, there are a plurality of cam shafts mounted on the upper platen 10, but only one of these cam shafts 106 is shown in the drawing, (see FIG. 2). The driving arrangement for the plural cam shafts in the upper platen 10 is exactly the same as the drive train for the plural cam shafts 100, 100a, 100b, etc. in the lower platen 14, which will now be described further with reference to FIG. 4.

As shown in FIG. 4, and as previously described, the drive pinion 126 meshes with driven gears 128 and 130. With the input shaft 110 rotating clockwise, as viewed from the righthand end in FIG. 2, it can be seen that the pinion gear 126 will be rotating clockwise as viewed from the lower end in FIG. 4. Consequently driven gear 128 and the cam shaft 100 are rotated counterclockwise, as viewed from the lower end. A drive gear 150 is keyed to the cam shaft 100 and an idler gear 152 is mounted on the cam shaft 100 and rotatable with respect thereto. In a similar fashion the cam shaft 100b carries a driving gear 150b and an idler gear 152b. Similarly, on cam shaft 100c, there is a driving gear 150c and an idler gear 152c. The other cam shafts also carry driving and idler gears but before referring thereto it is noted that the cam shaft 100e is also driven counterclockwise, as viewed from the lower end. The cam shaft 100e carries a driving gear 150e and an idler gear 152e. These driving and idler gears on cam shaft 100e mesh with idler and driving gears 152d and 150d on the cam shaft 100d. Similarly, the cam shaft 100f carries idler and driving gears which mesh with the adjacent gears on cam shaft 100e. Thus, all of the cam shafts 100, 100a, 100b, etc. are driven in a counterclockwise direction viewed from the lower end, which is the proper direction to advance the workpiece through the press. It is noted that the cam shaft drive arrangement just described permits a maximum number of cam shafts to be mounted on the platen and hence a maximum bearing area for support of the rails. The cam shaft drive arrangement for the cam shafts on the upper platen 10 is identical to that just described with reference to FIG. 4, it being understood, however, that the cam shafts in the platen 10 are driven in the opposite direction from those in the lower platen 14.

Referring now to FIG. 5, there is shown a detail of construction which is employed in the embodiment depicted in FIG. 1. It is noted that the rails 18 and 20, at the input end of the press, are formed with divergent surfaces on the respective heads of the rails. This construction provides a wider input area which facilitates the entry of the leading end of the workpiece and causes compaction of a bulky material over a desired distance of travel. Further, it is noted in FIG. 5 that the set of rails 18 are provided with bearing surfaces 96' similar to bearing surfaces 96, provided in the set of rails 20. Since the rails 18 would tend to fall off the cams 104 in the absence of a workpiece in the press, a retainer element 106 is inserted in the opening in the rail above each cam.

Referring now to FIG. 6, a temperature regulating system is illustrated for provided for either heating or cooling of the workpiece during its travel through the press. FIG. 6 is a plan view of the lower set of rails 20 and 20'. As previously noted, each of the rails is provided with a fluid passage 94 in the head of the rail (see FIG. 2). Such fluid passages are adapted for the circulation of a heat exchange fluid, such as oil, through the rails to maintain the rails at a desired temperature. The fluid circulation system includes a source 160 of high temperature oil which is connected by a supply conduit 162 to an inlet header 164. The header 164 has a plurality of outlets, one for each rail, which are connected respectively through flexible conduits 166 to the passages in the rails. The outlet ends of the passages in the rails are connected respectively through flexible conduits 168 to plural inlets of an outlet header 170. A return conduit 172 is connected between the header 170 and the return fitting of the source 160. In a similar manner a source 174 of low temperature oil is connected through a supply conduit 176 to the inlet header 164. The circulation is completed through the passages in the rails to the outlet header 170 and hence through a return conduit 178 to a return fitting on the source 174. In order to selectively connect either the heating fluid or the cooling fluid, control valves 180 and 182 are connected respectively with the sources 160 and 174. The connection of the conduits to the rails is also illustrated in part in FIG. 1. It is noted that the supply conduit 176 is provided with a slip fitting 182 to accommodate the adjustment of the position of the lower platen 14 relative to the base. Similarly, the return conduit 178 is provided with a slip fitting 184. In the like manner the supply conduit 162 and the return conduit 172 are provided with slip fittings (not shown). A similar temperature control system is provided for the rails 18 in the upper platen 10, so that heat exchange means through the rails is provided on both the upper and lower surfaces of the workpiece.

An additional embodiment of the invention is illustrated in FIGS. 7 and 8. In this embodiment a three-phase arrangement of the cams is employed to realize certain advantages which will be discussed subsequently. In the three-phase arrangement, the cams of a given set of cams are divided into three groups, and the cams in each group are displaced in phase from each other group by 120.degree.. This is illustrated in FIGS. 7 and 8, wherein a lower set of cams 200 includes a first cam 202, a second cam 204, and a third cam 206. Each of the cams is mounted on a cam shaft 208 for rotation therewith. Preferably the cams are in the form of circular eccentrics, as discussed with reference to the embodiment of FIGS. 1 and 2. As illustrated, the cam 202 is then at its top dead center position while cam 204 is displaced 120.degree. clockwise therefrom and cam 206 is displaced 120.degree. counterclockwise therefrom. As shown in FIG. 8, the rails 210, 212 and 214 are supported respectively on the cams 202, 204 and 206. With the cam 202 in its top dead center position the rail 210 engages the caterpillar belt 216 while the rails 212 and 214 are in an intermediate position. With the cam shaft rotating clockwise, as viewed from the righthand end in FIG. 8, continued rotation from the position shown will cause rail 210 to move forwardly and downwardly while rail 204 will move further forwardly and downwardly and at the same time rail 214 will continue moving upwardly and forwardly. It is noted that rails 216 and 214 will reach the same height at 60.degree. displacement after the top dead center position of rail 210. In the three-phase arrangement the transfer points are separated by only 60.degree. (as compared to 90.degree. for the two-phase). FIG. 7 also illustrates the phase relation of the cams in the upper platen 10. The cam 220 is in its bottom dead center position when the cam 202 is in its top dead center position. The cam 222 is displaced 120.degree. counterclockwise from the cam 220 and the cam 224 is displaced 120.degree. clockwise from the cam 220. This set of cams is mounted on a cam shaft 226 for rotation therewith. The cam shaft 226 is rotated in a direction opposite from the rotational direction of the cam shaft 208; consequently, the cams 220 and 202 first move toward each other to clamp and advance the workpiece, then the cams 206 and 224 move toward each other to clamp and advance the workpiece, followed by the cams 222 and 204 which move toward each other to clamp and advance the workpiece, the transfer points being spaced at 60.degree..

The three-phase arrangement provides a significant advantage in that the torque required to drive the press is caused to be more uniform by reason of the fact that the transfer points are spaced closer together in the angular displacement. Furthermore, the amplitude of the cyclical pressure fluctuations (which are eliminated by the hydraulic accumulator) are decreased relative to the two-phase arrangement because there is smaller difference in the minimum spacing between opposed cams and the spacing when the opposed cams are at their transfer points. It will now be appreciated that a multiple phase arrangement of higher order, such as a six-phase, will lend further advantage in respect to the above-mentioned operation.

In the operation of the continuous press the feedrate is suitably established by adjusting the speed of the prime mover. Because of the drive train previously described, synchronism and phase relationships are inherently maintained and the pressure applied by the press to the workpiece remains unaffected. It is noted that feedrate is also affected by the throw or eccentricity of the cams and for a given application the eccentricity and drive speed may be correlated to obtain the desired feedrate.

The illustrative embodiment described herein is provided with a substantially uniform gap through the press, as may be used for plywood or the like. However, for certain applications involving materials having a high bulk factor which are to be compressed, the platens may be disposed at an angle so that the gap through the press becomes progressively smaller as the material is thereby gradually compacted.

Although the description of this invention has been given with respect to a particular embodiment, it is not to be construed in a limiting sense. Many variations and modifications will now occur to those skilled in the art. For a definition of the invention reference is made to the appended claims.

Claims

The embodiments of the present invention in which an exclusive property or privilege is claimed are defined as follows:

1. Apparatus for simultaneously pressing and conveying a workpiece comprising a first platen having plural cams rotatably mounted thereon, a first set of rails disposed side-by-side with each rail mounted upon a different one of the cams, a second platen having plural cams rotatably mounted thereon, a second set of rails disposed side-by-side with each rail of the second set mounted upon a different one of the cams on the second platen, the first and second set of rails facing in a direction toward each other and spaced apart to accept a workpiece therebetween, means for rotating the cams to impart orbital motion to the rails, said orbital motion being in a plane parallel to said direction, the orbital motion of the first set of rails being clockwise and the orbital motion of the second set of rails being counterclockwise, said orbital motion of a first rail in the first set of rails being of opposite phase from the orbital motion of a first rail in the second set of rails, said orbital motion of a second rail in the first set of rails being phase displaced by a predetermined phase angle from the phase of the orbital motion of said first rail in the first set of rails, and said orbital motion of a second rail in the second set of rails being phase displaced by said predetermined phase angle from the phase of the orbital motion of said first rail in the second set of rails.

2. The invention as defined in claim 1 wherein said predetermined phase angle is equal to 360.degree. divided by the number of rails in the first set of rails which are out of phase with each other.

3. The invention as defined in claim 2 wherein the number of rails in the first set of rails which are out of phase of each other is equal to two.

4. The invention as defined in claim 2 wherein the number of rails in the first set of rails which are out of phase of each other is equal to three.

5. The invention as defined in claim 1 wherein at least one of said platens is yieldably supported relative to the other whereby the distance between the first rail in the first set of rails and the first rail in the second set of rails remains substantially constant throughout the orbital motion of the last mentioned rails relative to said platens.

6. The invention as defined in claim 5 wherein said first platen is supported in fixed position, hydraulic means supporting said second platen, said hydraulic means including an hydraulic accumulator to provide yieldable support for said second platen.

7. The invention as defined in claim 5 including first and second rollers disposed at opposite ends respectively of said first set of rails, a first endless link belt supported on said first and second rollers and encircling said first platen and first set of rails and in engagement with said first set of rails, third and fourth rollers disposed at opposite ends respectively of said second set of rails, a second endless link belt supported on said third and fourth rollers and encircling said second set of rails and said second platen and in engagement with said second set of rails, said link belts each comprising multiple links in the form of rigid bars spanning the respective sets of rails.

8. The invention as defined in claim 7 wherein each of said rigid bars is disposed in edge-to-edge contact with the adjacent bars to present a substantially continuous surface, said bars being of tapered cross-section to provide clearance from the adjacent bars when passing around said rollers.

9. The invention as defined in claim 7, including a first endless sheet belt encircling said first endless link belt and movable therewith and a second endless sheet belt encircling said second endless link belt and movable therewith.

10. The invention as defined in claim 5, wherein each rail is mounted upon multiple cams spaced longitudinally of each rail, all cams supporting a given rail being connected with said means and being rotated in phase with each other.

11. The invention as defined in claim 5 including a first cam shaft mounted on said first platen and connected to the cams mounted thereon, a second cam shaft mounted on said second platen and connected to the cams mounted thereon, and separate bearing means for each cam shaft adjacent each rail of the first set of rails.

12. The invention as defined in claim 11, wherein each rail in said first set of rails includes a web of narrower cross-section than the head of said rail whereby the webs of the rails may be separated by said bearing means and the heads of adjacent rails may be more closely spaced than the webs.

13. The invention as defined in claim 5 wherein said cam is an eccentric of circular curvature whereby said orbital motion of each rail describes a circular orbit.

14. The invention as defined in claim 11, comprising a prime mover, mechanical coupling means connected between the first cam shaft and the prime mover and connected between the second cam shaft and the prime mover, whereby said rails are moved in synchronism in their respective orbital paths.

15. The invention as defined in claim 14, wherein said mechanical coupling means comprises a first drive means connected between said prime mover and said first cam shaft for driving the cam shaft in one direction, and second drive means connected between said prime mover and said second cam shaft for driving said cam shaft in the opposite direction.

16. The invention as defined in claim 15, including plural additional cam shafts rotatably mounted in said first platen, each additional cam shaft including a separate cam coacting with each rail in the first set of rails, said first cam shaft and each additional cam shaft having a drive gear nonrotatably mounted thereon and an idler gear rotatably mounted thereon, the drive gears and idler gears all having the same number of teeth, said first cam shaft and one of said plurality of additional cam shafts being connected to said first drive means for rotation in opposite directions, the drive gear on each cam shaft meshing with the idler gear on each adjacent cam shaft, whereby all of the cam shafts rotate in the same direction.