Sewing Apparatus With Automatic Workpieces Stacking Means

Abstract

A workpiece stacking apparatus for a sewing machine for receiving workpieces after leaving the seaming area of the machine and stacking them in predetermined numbers on a movable support member in readiness for subsequent finishing operations.

Description

SUMMARY OF THE INVENTION

The present invention relates to a sewing machine and more particularly to an automatic workpiece stacking apparatus for such machines.

Sewing machines with automatic workpiece stacking devices are well-known which automatically remove the workpiece from a discharging station at the end of the seaming operation and place it in an area adjacent to the machine.

These well-known devices have been designed in various ways, for example with swinging arms and clamps which engage the workpiece in the area where it is left by the seam guiding devices and deposit it in a stacking area, or there can be provided movable surfaces which receive the sewn workpiece and overturn it causing it to fall onto a pile at the foot of the sewing machine.

These well-known stacking devices are designed with what is considered an excessive number of moving parts and the complexity of said devices necessitates frequent attention for assuring satisfactory operation thereof. An undesirable condition often presented in the known stacking devices is that workpieces received from the sewing station are often inaccurately stacked and require additional handling by the operators. Another undesirable condition prevalent with the known stacking devices is that of frictional engagement with the workpiece by the various moving elements which induces wear especially on workpieces of finer quality.

The present invention provides a sewing machine with an automatic workpiece stacking apparatus for successively receiving each workpiece after it is sewn and accurately stacking the same on top of the previously sewn workpiece.

With the sewing machine according to the present invention the same clamping member moves the workpiece from a charging station, through a seaming area and then to a discharge area or station where the workpiece is engaged by an auxiliary element which holds it in position to be acted on by the stacking apparatus.

The main aim of the present invention is to provide a sewing machine with an automatic workpiece stacking apparatus which eliminates the above-mentioned problems.

A further aim of the present invention is to provide such an apparatus having a support member in the form of a movable dolly operatively associated with the discharge area and of which the workpieces coming from the sewing station are stacked and held in readiness for moving to other machines which carry out the subsequent finishing operation.

A further aim of the present invention is to provide a sewing machine with an automatic workpiece stacking apparatus with the necessary safety device according to which a predetermined number of workpieces with a perfect seam only are stacked.

Further aims, advantages and characteristics of a sewing machine with an automatic workpiece stacking apparatus according to the present invention will become more fully apparent by reference to the appended claims and as the following detailed description proceeds in reference to the figures of drawing wherein:

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a perspective view of a sewing machine showing the apparatus according to the invention applied thereto,

FIG. 2 is a plan view of the sewing mechanism shown in FIG. 1,

FIG. 3 is a perspective view of a portion of the mechanism in FIG. 1 showing further detail of the workpiece stacking apparatus,

FIGS. 4a and 4b show a side view of the apparatus shown in FIG. 3 drawn in successive phases of the stacking operation,

FIG. 5 is a schematic view of the pneumatic control circuit of the apparatus according to the present invention.

It should be understood that the automatic workpiece stacking apparatus according to the present invention could be applied to various types of sewing machines that utilize movable clamping members for moving a workpiece on the work supporting surface of the machine. In the drawings there has been shown a particular embodiment of the sewing machine whose electro-pneumatic controls for carrying out successive seaming cycles are arranged in circuit with and disposed so as to effect actuation of the workpiece stacking apparatus.

With reference to FIGS. 1 and 2 the sewing machine mechanism is essentially formed by a supporting frame 1 and a work supporting surface 2 on which the workpiece to be sewn by a fixed sewing machine 4 is caused to slide by means of a clamp 5 carried by a carriage 3 that is movable along the length of said surface 2. Telescopic-like guiding elements 6 and 7 provide a means for the transverse movement of the clamp and workpiece carried thereby. A pneumatic cylinder 8 when activated centrally locates the clamp 5 which is central in relation to a longitudinally extending guide element or positioning strip.

The contoured guiding element 9 is part of clamp 5 and reproduces the contour of the seam to be sewn. Located at the area where seaming is to begin is located a fixed element or template 10 whose contour matches that of the clamp 5. The sewing machine 4 has a fixed pin 11 which loads with the contour guiding element 9 to impart to the clamp 5 a transverse component of movement while telescope-like means 6 and 7 maintain a biasing pressure in clamp 5.

The advance to the sewing station and then to the discharging station and the reverse run to the charging station made by the carriage 3 are performed by a motor 12 through a driving belt or chain 13. The movement in one direction or the other of the carriage 3 is controlled by a coupling 14 which can be inserted into the upper or lower branch of the chain 13 by operation of pneumatic cylinder 15. At the discharging station there is in the work supporting surface a door or opening 16 in which all the workpieces coming from the sewing station are discharged to be stacked in a pile.

Referring now to the FIGS. 3, 4a and 4b a stacking device 17 is shown in all its details. It is essentially formed by two pneumatic cylinders 18 and 19, the first of which is a double acting cylinder while the second is a cylinder on that always exerts a constant, unidirectional biasing force against part of the piling mechanism, as explained more fully below.

In front of the stacking device 17 there is located a carriage 20 suitable to hold and receive sewn workpieces.

The carriage 20 is formed by a frame 21 having wheels 22 for easy movement. A couple of vertical frame elements 23 joined above by a tubular element 24 are hinged on two brackets 25 and elastically biased by springs 26 toward the frame 21. Above the frame 21 there is mounted an inverted down U-like element or support member 27 against whose vertical wall 28 the said tubular elements 24 is held by springs 26.

At the lower end of the said frame 21 there is a rack 29. The carriage 20 is also fitted with a handle 30 and a C-like base 31 so that it can be introduced underneath the supporting frame 1 of the sewing apparatus in alignment with the door 16 on the work supporting surface 2.

Before starting the sewing phase it is necessary to operate a suitable manual control 32, for example a pedal, to open the clamp 5 and insert the workpiece to be sewn, and then operate again the said control to close the workpiece clamp.

Complete clamping of a workpiece also requires operation of pneumatic element 3 which results in operation of a cylinder 34 that is hinged on a bracket 35 fixed to the carriage 3. This cylinder 34 operates the clamp 5 by virtue of having piston 36 connected to said clamp.

When the compressed air is introduced into the cylinder 34, the clamp 5 is opened and vice versa, when the cylinder 34 is discharged, the clamp closes again.

As placing of the workpiece in the opened clamp is effected with the help of the template 10, the template must be moved away from the work supporting surface after operation of control 3 so as to avoid any interference between it and the clamp 5 when it is closed.

At this point the cycle can be started by pressing a starting knob 37 (FIG. 2) which, besides starting the motor 12 and therefore the driving chain 13 regulates the direction of movement of the carriage 3 towards the sewing machine 4. Owing to the pressure on the knob 37 the carriage 3 moves the workpiece towards the sewing machine. The machine does not start working until the lower edge of the workpiece or of the clamp 5 covers a sensing element 38, in particular a photocell which, once the seaming is over, also stops the machine. The photocell also has the tasks of making a thread cutter 39 work so as to free the workpiece from the needle 40 and to cause backward operation of a stacking device 17.

When the front edge of the workpiece gets to the edge of the opening 16 it slips into it and the carriage 3 continues to move forward.

The stacking device 17 which during the whole sewing operation is in a retracted position, becomes operative once the workpiece begins to fall into opening 16. Cylinder 19 first clamps the workpiece against vertical wall 28 of element 27. Subsequently cylinder 18 moves the remainder of the workpiece over the top of element 27 where the workpiece is then stacked.

This is effected by the arms 44 which are carried on rod 43 then can be moved back and forth by the piston 41. These arms 44 press against the spring biased elements 23 and 24 to move them out of the way and permit the end of the workpiece to fall into the stacked position shown in FIG. 4b.

The pressures in the cylinders 18 and 19 are identical but the cross-sectional area of the stacking cylinder 18 is much larger than that of the cylinder 19 so that there is such difference in power that, although the piston 42 is always biased in one direction it can be forcibly moved to its retracted position by piston 18 acting through the arms 44 when they contact rod 46 during return movement of piston 18.

Thus the leading edge of a workpiece 47 strips into the opening 16 and slides down through this aperature along the frame 21 towards the rack 29 as the clamp 5 holds it at the opposite end.

During this time the stacking device is in the position represented in the FIG. 4a with the piston 41 completely withdrawn. The carriage 3 and the clamp 5 continue to move forward until they free the tracking edge of the workpiece which is not held on the work supporting surface any more.

As the opening door 16 is located near the sewing machine 4, the workpiece has already begun to go down through this opening while its back edge is still being sewn by the machine. As soon as the latter stops working owing to the time-regulated pulse of the sensitive photocell element 38 the piston 41 also starts moving forward at the same time as the clamp 5 and this moving brings the transverse rod or bar 43 against a trailing portion of the workpiece. This trailing portion is carried over the top of element 27 and is then released because the wide arms 44 are in contact with the tubular element or rod 24 to move it away from element 27.

At the same time the piston 42 can move forward following for a certain distance the movement of the wide arms 44 to hold the longest edge of the workpiece 47 against the frame 21.

As a matter of fact the holding occurs just a little before the said piling or stacking action and the release of the workpiece by clamp 5 to prevent the said workpiece from falling.

At the end of the forward run of the piston 41, the position is the one shown in the FIG. 4b, in which there is shown the workpiece 47 with its longer edge held by a holding rod 46 and the shorter edge laid over the element 27. Once this has occurred, the piston 41 automatically retracts and therefore also the rod 43 and the wide arms 44 move to the rest position.

During retraction of piston 18, the wide arms 44 first leave the tubular element 24 which, biased by the springs 26 will hold the short edge of the workpiece 47 against the wall 28 of the fixed element 27. They therefore cause rearward movement of the rod 46 and of the piston 42 of the cylinder 19. At the end of the backward run the positions are again those shown in FIG. 4a with a workpiece 47 on the carriage 20 stacked on the frame 21, and held by the tubular element 24.

The working cycle of the stacking device 17 is controlled by a pneumatic circuit (FIG. 5) which includes a couple of control elements, in particular two electro-valves 48 and 49 energized by the sensor element 38 (FIGS. 1 and 2) which senses the position of the workpiece 47 on the work supporting surface 2 of the sewing machine.

When the sensitive element 38 assumes its so-called rest condition, it causes the energizing of both electro-valves 48 and 49. The first of the two when energized opens the valve with which it is fitted thus allowing the passage of a flow of compressed air from a normal feeding line 50 towards a distributing valve 51 normally open through a duct 52 and from the latter to the other electro-valve 49 which is in the same condition of the first being actuated through another duct 53.

At the same time the flow of air coming from the electro-valve 48 passes through a regulator 54 and is received by a pneumatic tank 55 connected with the distributing valve 51 into which it is directed and effects interruption of flow of compressed air when it is completely filled.

When the compressed air is permitted to pass through the distributing valve 51 (normally open), and a further duct 56 connecting the electro-valve 49 with a one-way distributing valve 57, the latter is caused to reverse the connections which the feeding line 50 has with the two-way cylinder 18 through the two ducts 58 and 59. In particular, line 50 is connected by means of a duct with the forward portion of the piston 41 keeping it in its retracted position when the one-way distributing valve 57 is not affected by air flow coming from the normally-open distributing valve 51. Likewise when the distributing valve 57 is actuated by air coming from the distributing valve 51 due to the actuation of the electro-valves 48 and 49, being the line 50 connected by means of the duct 59 with the rearward portion of the piston 41 pushes it forward to discharge the air contained in the cylinder 18 to the outside through a flow regular 60 which regulates the discharge thereof from the piston 41.

The moment in which the pneumatic tank 55 is completely full, and filling time of which is controlled by adjustment of the regulator 54, the distributing valve 51 (normally open) is closed effecting interruption of the flow of compressed air from the line 50 to the one-way distributing valve 57 through the first electro-valve 48, the duct 52, the distributing valve 51, the duct 53, the second electro-valve 49 and the duct 56. This interruption of air flow returns the one-way distributing valve to its original statement causing the return of the piston 41 to its retracted position.

During the seaming cycle, there is no compressed air in any named duct which are opened to the outside, with the exception of the duct 58 which is connected with the line 50 as described above. When the stacking apparatus 17 is started, a pulse is first sent to a counter, actually a relay suitable for this purpose, while another counter is adjusted for a predetermined number of workpieces which is desired to stack on each dolly. The pulse received at the end of each seaming cycle corresponds to a figure in the first counter, when the number reached in the latter is equal to the predetermined number of the second counter, then a safety device will actuate to prevent a successive cycle from being carried out. This is to prevent an excessive number of workpieces from being stacked on only one dolly, that would result in an excessive number of layers of workpieces causing inadequate operation of the clamp, etc. There could be provided known elements suitable to signal the approaching of the highest figure of workpieces predetermined in the second counter which would enable an operator to replace the dolly without interrupting the working cycle. A special device (not shown) senses the presence of the threads so that in case of their breakage the stacking device 17 is automatically deactivated and the faulty workpiece coming to the device will not be engaged by the rod 46 because it is kept in its retracted position. This will cause the faulty workpiece to fall into the container 29 without being stacked. It is to be understood that some construction particulars have not been described in the above description, both because they are quite well-known to those conversant in the art and are not essential to the aims of the present invention. For example it would be preferable to provide for the positioning of the stacking dolly 20 in a way that would permit a transversal rod in the frame 21 (FIG. 3) between the fixed elements thereof and preferably connected to its vertical standards. This would reinforce the structure of the dolly and avoid possible damage thereto during actuation of the cylinders of the stacking device 17.

Additionally it should be understood that the pneumatic cylinders for actuating the various elements of the invention could be replaced by different types of actuating devices such as, for example, electromechanical elements.

Although the present invention has been described in connection with a preferred embodiment, it is to be understood that modifications and variations may be restored to without departing from the spirit and scope of the invention as those skilled in the art will readily understand.

Such modifications and variations are considered to be within the purview and scope of the invention and the appended claims.

Claims

I claim:

1. In a sewing machine of the type including a supporting frame having a work supporting surface forming the upper portion thereof and a carriage attached to and movable along the latter with a clamping member connected to the carriage for moving a workpiece along the supporting surface from a charging station through a seaming area to a discharge area, a workpiece stacking apparatus comprising;

a. a support member disposed below and in communication with the supporting surface for receiving a workpiece from tthe discharge area;

b. holding means carried by the supporting frame for engaging the workpiece intermediate its ends and moving it into engagement with said support member;

c. stacking means operatively connected to said holding means for moving and draping an end of the workpiece over said support member, and;

d. a clamping member operatively associated with said support member and movable between positions for permitting stacking of workpieces on said support member and clamping the same thereto.

2. The workpiece stacking apparatus according to claim 1 wherein said support member defines a wheeled carriage movable into and from its workpiece receiving position.

3. The workpiece stacking apparatus according to claim 1 wherein said holding means includes a pneumatically-controlled holding rod disposed transversely of the direction of movement of the workpiece.

4. The workpiece stacking apparatus according to claim 1 wherein said stacking means includes a pneumatically-controlled bar member disposed transversely of the direction of travel of the workpiece and rod elements operatively associated with each end of said bar member for guiding the latter in a horizontal path between an inactive position and the position at which it places the workpiece on said support member.

5. The workpiece stacking apparatus according to claim 4 wherein said pneumatically controlled bar member includes a depending arm on each end thereof slidable on said rod elements during movement of said bar member to effect the opening and closing of said clamping member.

6. The workpiece stacking apparatus according to claim 5 wherein said clamping member defines a pivotable tubular element movable to and from clamping contact with workpieces deposited on said support member.