Machine For Screen Printing On Long Tables

Abstract

Automatic apparatus for screen printing on textiles on a long table. A travelling carriage is pneumatically driven stepwise on rails and guided by guide-wheels cooperating with guide rails. A printing frame having a screen thereon is transported by the carriage. The frame is lowered automatically to apply the screen to the surface, such as a fabric, on which printing is to be effected. A squeegee is operated automatically applied under pressure to the screen and a doctor blade is reciprocably driven to effect inking and printing on the fabric surface. The carriage transports a valve system that sequences intermittent stopping of the carriage and while the carriage is stopped effects automatic lowering of the frame and screen, lowering of the squeegee, the forward and backward movement of the doctor blade, stopping of the blade, and sequential lifting of the squeegee and frame and advancement of the carriage to its next stop position where the above steps are again effected.

Description

This invention relates to improvements in the construction of automatic machines for textile printing on a long table. Thanks to these improvements it is possible to construct completely automatic machines which allow their automatic mechanisms to be partially or totally interrupted and re-connected later on, as desired.

For the correct interpretation of the invention, the following description will give a non-restrictive example of practical performance.

FIG. 1 Full diagram of the machine, parts of which are shown intersected.

FIG. 2 Details of the intersected parts as in FIG. 1, but at larger scale.

FIG. 3 Distribution of the accessories to be mounted upon the table.

FIG. 4 Distribution on switchboard

FIG. 5 Table and machine with air-compressor. Table and machine show the opposite side of that shown in FIG. 1.

FIG. 6 Detailed view of impulse claw, stop claw and repeat stop.

FIG. 7 Detailed view of mechanism for operating the doctor blade.

According to the invention, a carriage 1 has four wheels two of which are designated by the reference (2) and are grooved and guide the carriage 1 upon a cylindric rail 3 fixed at one side of the table. The two plain wheels 4 keep the carriage 1 upon an angle bar 5 opposite and parallel to the rail 3. In order to assure a stepwise drive and stop, the carriage is disposed over two claws or pawl, i.e., an impulse claw 6 and a stop claw 7. When the machinery stops, the stop claw 7 engages the side of one of the repeat stops 8 distributed along the table 9 and retains the carriage 1, whilst the impulse claw 6 leans against the other side of the repeat stop 8 pressing it. Thanks to the anchorage and pressure described, the carriage 1 is releasably blocked and unable to move.

In order to drive the carriage 1 along, a general pneumatic circuit of the machine brings the stop claw, or fix-damping pawl 7 in sidelong and rotary movement, and when the anchorage is released, by release of the repeat stop 8, the impulse claw, or drawing impulse pawl 6 provides for sufficient thrust allowing the carriage to continue advancing by its own inertia when the impulse claw 6 discontinues pressing the repeat stop 8. Once the impulse claw 6 is engaged on its back side by the next repeat stop 8, it retracts and reappears then at the other side of that same repeat stop 8 that retracted it and it then applied pressure to it. At the same time the shaft 10 of the stop claw 7 advanced and rotated to put the claw 7 into the right position for the next stop. The shaft 10 is connected with a hydraulic shock-absorber by means of which it brakes and damps the carriage 1 which is advanced by its own inertia.

The stop claw's 7 shaft is grooved in an axial direction and its bearing 12 has coincident grooves so that the shaft 10 may slide through the bearing 12 during the braking phase and when the stop claw 7 bears against the repeat stop 8. Shaft 10 and the bearing 12 rotate to turn the stop claw 7 away or retract it from the repeat stop 8 and subsequently advance into position and then rotate again changing thus once more the stop claw's position for its anchoring or stopping the carriage the next repeat stop.

A brake consisting of a piston 13 and a cylinder 14 is located opposite to the claws 6,7. The piston rod pressures, when emerging, a forcer lever 15 which, in turn, pressures a stem 16 extreme of which serves as a jaw of a gripper of the rail 5. Blocking of the carriage 1 at the claws' 6,7 opposite side and centering of the chase 18 through the stem's 16 upper conic end are thus effected.

When the shaft 10 reaches its utmost advance point during one forward step of the carriage 1, a cam 20 at the shaft's free end moves the stop-control valve 21 incorporated in the machine's pneumatic system. Said valve 21 transmits compressed air to the cylinder of a piston 19 which operates the impulse claw 6 and to the cylinder 14 of the brake piston 13 as well as to the upper part of a cylinder 22 of a piston 23 which lowers the chase 18. During the chase's 18 descent a connecting rod simultaneously drives a disk cam 25 which operates another valve 26 of the general pneumatic system.

The valve 26 operated by said disk cam 25 controls a piston or plunger 28 which inclines a form-inking doctor blade 33 linked with an arm 34; the latter also is connected with a slide 38 which slides upon a transversal guide 40 fixed upon the carriage 1. Once the doctor blade is dropped down, a piston 29 connected with a swinglever 30 and with the doctor blade arm 31 transmits an adjustable downward pressure to the arm 34, whilst the slide 38 is operated by means of a piston 45 of a cylinder 46.

The cylinder of the pressure stem 29 and those of the doctor-blade inclining plungers or pistons 27, 28 are located upon the slide 38 which travels, as mentioned, upon a transversal guide 40.

The slide 38 is driven by an arm 41 which consists of two pieces connected by an elbow-link: forearm 43 and arm 41. The latter is linked with the upper part of the carriage 1.

The forearm 43 is linked with the piston rod 44 of a piston 45 of the horizontal cylinder 46 which is link-connected with the machine chassis.

The slide-driving arm 41 holds a slipper 47 with two contact plates 48; it slides a short way on said arm 41 and is linked with the forearm 43 by means of a connecting rod 49. The forearm 43 commands the slipper's 47 come-and-go or reciprocal motion.

The slipper's contact plates 48 alternatively pressure, during the slipper's travel, the two rollers 51, 52 which connect the valves 53, 54 with the pneumatic system of the machine. The valve 53 next to the forearm 43 serves the following purposes: (a) to incline the doctor blade 33 in a backrun sense; (b) to produce a new downward pressure on the doctor blade arm 34; (c) to cause the backward sliding of same and of the slide 38 through a cylinder 46 linked with the forearm 43.

The valve 53 assures the run-back or return of the doctor blade 33 by sending compressed air to the pistons 27 of a cylinder 63 fixed on the slide 38, whilst a new adjusted downward pressure on the doctor blade arm 34 is obtained by the transmission of compressed air to the cylinder of a piston 29 which at first served the same purpose.

When the slide 38 runs back, the slipper 47 operates the valve 54 allowing compressed air to pass to the piston 23 of the cylinder 22 which serves to elevate, lower and fasten the chase 18. When the latter desengages and lifts up, it operates via a connecting rod 24 the disk cam 25 which controls another valve 55 of the general pneumatic system. Through the stem 56 of a cylinder 57 the valve 55 drives the grooved shaft 10 of the stop claw 7 and when the latter separates from the repeat stop 8 it allows the carriage to advance under the effect of the impulse claw 6 which is commanded by the piston 19 of a driving cylinder 58.

The carriage 1 is provided with a vertical contact finger 59 long enough to detect and touch the stop repeats 8 and to pass them when it temporally lifts. The contact finger 59 is connected with an eccentric 60 which follows its movements and operates a valve 61. The latter transmits compressed air to the piston of a pneumatic-hydraulic converter which provides the cylinder 58 of piston 19 with oil pressure. The grooved shaft 10 then moves backward with rotary movement and at same time the valve 61 -- which operated the shaft 10 before -- drives back said piston stem 19 of the cylinder 58 of the impulse claw 6, assuring the next stop.

The shaft 10 is driven via the pneumatic-hydraulic converter; it rotates under the effect of compressed air and is hydraulically braked.

The alternative turn of the doctor blade 33 at the end of the slide's 38 runway is of approx. 70.degree.. The alternative turning is produced by the swinglever 30 operated by means of the pistons 28, 27 of the cylinders 62,63. The latter are fixed upon the extremes of said swinglever 30 and are supplied air by the valves 26, 53.

At same level of a nose 64 at the elbow 42 of the slide-operating forearm 43, the carriage has an advance-limiting stop 65 for said elbow 42 which assures an equal running of the slide 38.

The link connection between the slide 38 and the forearm 43 is adjustable at will with a screw 67 of the gripper 68 which rides upon a traverse 69 of the slide 38. This allows adjustment to determine the most favourable and convenient position at the right, the left or in the center of that regulation zone.

The slide-moving forearm 43 and the doctor blade arm 34 are partly telescopic both elements (66 and 35 respectively allow telescoping). This allows to adjust the forearm's length (which determines the runway length of slide) and to obtain the best adapting of the doctor blade arm 34 to the size of the chase 18.

In relation to the forearm 43, the elbow 42 of the arm 41 shows in its most extended position an obtuse angle and in its most reduced extension a sharp angle.

The connecting rod 70 is linked at one end with the elbow 42 of the arm 41 and at its other end with the arm 71 of a hydraulic damper 72 which is fastened, without lateral displacements, upon the carriage 1 and serves for the progressive braking of the forearm 43 at the slide's runway end.

The carriage 1 is provided with a regulating device which allows to stop it during advance movement at all or at certain pre-selected repeat stops 8.

After its stepwise advance, the carriage 1 is returned rapidly and steplessly to its starting point by means of a pneumatic motor and arrested by a damper stop 74.

The air-motor 73 does not work on the entire backrun length but only thrusts the carriage 1 until it arrives at a connecting rod 75 fixed on the table for the purpose of operating a valve which commands motor's air supply. Thanks to the push received, the carriage 1 then continues its backward run by own inertia until arriving at a stop claw 76 which pressures a helicoidal spring 77 at the carriage side and when that claw engages, the carriage is softly or smoothly arrested.

When the lever 78 connected with the spring's 77 end pressures the advance stop 79, a side -arm 80 of same lever 78 retires releasing the valve 81 which then no longer hinders the air-flow to the pneumatic motor 73 which is started up and sends the carriage 1 back to its starting position where it begins a new working cycle.

Air coming from the compressor 82 flows through a flexible tube 83 wound on a drum 84. Said tube 83 is connected at one end with the machine's air circuit by a quick-fitting union 85 and at the other end with the compressor's 82 main conduit by a fitting union in the drum core.

The winding and unwinding of the flexible tube 83 only takes place during the stepwise advance and the air-motor driven backrun of the carriage 1. A flexible tie 87 goes from the carriage 1 to the advance starting point at the table 9 and from there via a pulley 88 along the table to the neck of the drum 84. The flexible tie 87 provides the tube winding and unwinding by rotating the drum 84 in clock or anti-clock direction respectively. The carriage 1 determines the tube's length by commanding the drum motions via the flexible tie 87.

The surfaces of both sides of the repeat stops 8 and the contact faces of the claws 6,7 are mechanized for smooth coupling without compensation joints.

The switchboard is provided with switches not shown for the interruption of the automatic functions and for hand-operation of certain working phases.

The impulse claw 6 is link-connected with a slipper 94 fixed at the plungers end 92, i.e., at the end of a prolongation of the piston 19 of the cylinder 58. The impulse claw is lifted or lowered by a counterspring 91. During the backward move of said cylinder prolongation 92, the counterspring becomes inactive when the impulse claw 6 strikes against and and applies pressure to the arrester 95.

The runway slot of the impulse claw 6 is crossed by a small bridge 96. When moving backward, the impulse claw 6 is always obliged to lower and pass under the small bridge 96, even if for special circumstances it would not retract by its own retracting means.

The beveled surface 97 of the stop claw's 7 backside represent a safety ramp and during the backrun phase of the carriage the claw is retracted or deflected at all repeat stops 8, even if it has not separated or retracted from the repeat stop path.

Having described fully the nature of the invention and its practical realisation, it is understood that this is liable to variations in detail without altering the fundamental principle which constitutes the essence of the invention.

Claims

What I claim is:

1. Automatic apparatus for screen printing on fabrics and the like comprising, a travelling carriage movable stepwise, carriage-advance means to drive the carriage stepwise comprising, a driving impulse pawl movably mounted for deflection downwardly upon application of downward pressure thereto and upwardly to a raised position, drive means for applying driving impulse pressure to said driving impulse pawl in a direction toward which said carriage is to be advanced, a plurality of stops associated with said carriage disposed spaced from each other to be engaged sequentially by said driving impulse pawl for receiving an impulse therefrom for advancing said carriage stepwise, a fixing -- damping pawl for engaging the stops sequentially while being advanced by said driving pawl and releasably holding each stop temporarily clamped between it and said driving pawl for stopping advance of said carriage at a stop position, mounting means mounting said fixing-damping pawl including means mounting it for limited travel in a damping stroke from a rest position toward the direction of advancement of said carriage when engaged by each stop and restoring said fixing-damping pawl subsequent to each damping stroke to said rest position, means for moving said fixing-damping pawl out of the path of said stop after stopping each said stop while driving pressure is being applied thereto by said driving pawl so that said carriage advances free of both pawls upon release thereof and for subsequently returning said fixing-damping pawl to said rest position in the path of travel of said stops for engagement by a next successive stop, said driving impulse pawl being disposed in the path of travel of said stops when in said raised position for engagement successively by said stops for application of downward pressure and deflection downwardly thereof, means raising the driving impulse pawl to said raised position after deflection downwardly by the individual stops, whereby when deflected downwardly by each stop it is restored to said raised position for engagement with the individual stop for applying pressure thereto for advancing said carriage.

2. Automatic apparatus for screen printing on fabrics and the like according to claim 1, including a frame for a screen transported by said carriage, means for lowering said carriage to a printing position and raising it while said carriage is temporarily stopped when the individual stops are clamped between the driving impulse pawl and the damping fixing pawl.

3. Automatic apparatus for screen printing on fabrics according to claim 2, including a doctor blade transported by said carriage, and means for actuating said doctor blade for inking and printing while said carriage is temporarily stopped.

4. Automatic apparatus for screen printing on fabrics according to claim 1, including means to restore said carriage steplessly to a start position after advancement thereof stepwise.

5. Automatic apparatus for screen printing on fabrics and the like according to claim 1, in which said drive means comprises a pneumatic cylinder.

6. Automatic apparatus for screen printing on fabrics and the like according to claim 5, including means controlling application of impulses of said driving impulse pawl.