US2623224A

US2623224A - Driving arrangement for shoemaking machines

Info

Publication number: US2623224A
Application number: US737073A
Authority: US
Inventors: Zaoral Josef; Ostrcil Vilem
Original assignee: BATA NARODNI PODNIK
Current assignee: BATA NARODNI PODNIK
Priority date: 1944-09-30
Filing date: 1947-03-25
Publication date: 1952-12-30
Anticipated expiration: 1969-12-30

Description

Dec. 30, 1952 J. zAoRAL ET Al. 2,623,224

DRIVINGl ARRANGEMENT FOR SHOEMAKING MACHINES Filed March 25, 1947 4 Sheets-Sheet l 17?:1 ,Ii I! f3; i l

2 2 Q /56 fea 3 3' Dec. 30, 1952 2,623,224

J. ZAORAL. l-:T AL

DRIVING ARRANGEMENT FOR SHOEMAKING MACHINES Filed March l25, 194'? 4 sheets-sheet 2 3 wwe/MMSI Dec. 30, 1952 J. zAoRAL ET A1. 2,623,224

DRIVING ARRANGEMENT FOR SHOEMAKING MACHINES Filed March 25, 1947 4 Shee'rls-Sheet 3 Dec. 30, 1952 J. zAoRAL ET AL 2,523,224

DRIVING ARRANGEMENI FOR SHOEMAKING MACHINES Patented Dec. 30, 1952 DRIVING ARRANGEMENT FOR SHOEMAKING MACHINES Josef Zaoral, Dily-Zlin, and Vilm Ostril, Horni Mostenice, Czechoslovakia, assgnors to Bata, Nrodni Podnik, Zlin, Czechoslovakia Application March 25, 1947, Serial No. 737,073 In Germany September 30, 1944 Section 1, Public Law 690, August 8, 194i, Patent expires September 30, 1964 12 Claims.

This invention relates to a driving arrangement for pulling over machines, toe tacking machines and the like shoemaking machines, in which the upper part of the shoe is stretched over the last by means of a system of stretching nippers which alternately close and open, perform pulling and lateral motions, in some cases a rotary motion about their own axis and also the corresponding return motions, and has for its object an improvement in the drive of the nippers. ing to the invention this is elected by the provision of a hydraulic drive with diiferential pistons and a spring-loaded by-pass valve between the latter, which parts co-,operate in such a manner that, during the stretching motion of the nippers, the tractive force of the nippers increases in the ratio of the increasing resistance of the upper up to a definite maximum value, the closing force of the nipper jaws increasing simultaneously to a corresponding extent.

The stretching nippers of pulling over and toe tacking machines have essentially two fundamental operative functions to perform, namely the clamping of the marginal portion of the upper between the nipper jaws and the stretching of the upper through the pull of the nippers. To these fundamental functions of the nippers must be added lateral evading motions which are necessary, when the nipper jaws are opened, in order to free the place being operated on for fixing means, and of course all return motions after the completion of the operation. In the case of those nippers which are operative in the ball part of the shoe, that is, the so-called ball nippers, a rotary motion of the nippers about their longitudinal axis as well is desirable, in order to ensure a correct adaptation and stretching out of the upper in the instep arch of the last.

The correct tacking of a shoe upper, that is, its iim'ng on the inner sole of the shoe, is mainly dependent on the correct stretching of the upper on the last and the pulling over round the edge of the last and the inner sole, which operations are regulated by the grip and pull of the stretching nippers. The material of the shoe upper, that is usually leather, has the peculiarity, that at rst it offers to the tensioning force a relatively low resistance which gradually increases as the pulling operation proceeds, until it reaches a definite extreme value. the exceeding of which would result in the upper part tearing. This extreme value must therefore never be exceeded, when the upper part is being stretched over the last, with the further object of insuring that the Shoe will retain the requisite elasticity, even after the tacking on of the upper part.

Accord- (o1. iz-c) With the arrangement accorchng to the present invention it is intended iirst of all to solve the problem, for the correct stretching of lan upper part corresponding to the nature of the leather, to follow a procedure which has proved to be the best in the stretching and tacking on operation by hand after years of experience, as the worker first of all, after gripping the marginal portion of the upper, applies a gentle pull which he increases in accordance with the increasing resistance of the upper, at the same time increasing the force required for holding the upper part in the nippers. An advantageous feature of the arrangement according to the invention resides in the simplicity o1" the construction, in the possibility of controlling individual groups of nippers by themselves and not least in the circumstance, that the upper can in every working phase of the machine be liberated from the nippers by a single movement of a lever.

Owing to the circumstance, that with the purely hydraulic drive according to the invention the closing force of the nipper jaws is hydraulically controlled together with the pull of the nippers, a considerable simplification of the entire device results, although each nipper has its individual drive and thus represents an independent working element, of which some, through being connected to common control valves, form the usual working groups, such as toe nipper, side nippers and perhaps ball nippers. The individual working nippers are supported by working cylinders capable of being fixed in any position on the machine frame, in which cylinders the pistons supporting the xed nipper jaw move, whilst the movable nipper jaW is mounted on a rod which at one end is also formed as a piston and is guided within the piston casing of the xed nipper jaw. This arrangement provides differential pistons with an intermediate space which is in communication with the cylinder space of the working cylinder by way of a springloaded by-pass valve. Through the inilow of the pressure iiuid the closing of the nipper jaws is thus first of all brought about by a relative displacement of the two pistons with respect to one another and linally, through the joint movement of the two pistons in the working cylinder, the pulling motion is produced, in which during the equalization of pressure in the spaces between the diiferential pistons and the working cylinder the said increase of the pulling force and the nipper closing force takes place. An axial rotary motion of the nippers, if required, is derived from the sliding motion of the same in the working cylinder. The gripping of the marginal portion ci the upper by the nipper jaws and the tensioning oi the upper through the pull of the i' is effected by the worker through controllin appropriate valves by means of a knee-actu lever, whereby he can control each group or nippers independently not only in regard to tl^ working position, but also for the purpose of -c turning it into the initial position, which is of great advantage, if the marginal portion of the upper should by chance have been incorrectly gripped and tensioned by only one group of nippers. Only after the upper has been correctly stretched over the last are the valves controlling the nippers changed over to the cam shaft of the machine, which can then automatically carry out the further work, such the forming and tacking on of the upper.

Further advantages and features of the present invention will be gathered from the following description with reference to a constructional example illustrated in the accompanying drawings, in which:

Figure l shows adiagrammatic representation of the whole driving arrangement according to the invention;

Figure 2 a longitudinal section through the stretching nippers in the initial position;

Figure 3 a detail of the working cylinder of the nippers in section (in the upper part of the gure the parts are in a position, in which the nipper jaws are closed, but the nippers themselves are not yet exerting any pulling force, whilst the lower part of the figure shows the position ci the parts, when the nippers are exerting the pull);

Figure 4 a view oi a control slide valve in part section with the piston in the initial position;

Figure 5 a diagrammatic representation of one of the control chambers with the piston in a middle position;

Figure 6 the same control chamber as Figure 5 with the piston in the extreme left-hand tion;

Figure l a diagrammatic representation of the idle running slide valve in cross-section, and

Figure 8 a detail of the means for driving the piston of the idle running slide valve.

The arrangement for stretching the toe Aart i the shoe upper over the last consists in the tacking machine constructed according to the invention of the usual system of stretching nipper, of which the nippers I (Figure l) represent the toe nipper, the nippers 2, 2 the side nippers and 3, 3 the nippers for applying the pull in the ball region, the ball nippers. The number of pairs of nippers could, of course, be increased according to requirement. The individual nipper arrangements diier from one another only in the shape of the jaws and, as regards the ball nippers 3, 3 also in this, that the latter are provided with a device which enables these nippers to turn about their longitudinal axis, which is not necessary in the case of the toc and side nippers.

The drive of all the nippers is fully hydraulic. The pressure fluid, for instance, oil, is conveyed by a pump 4 driven by the electric motor 5 from a container 6 through the pipe l by way of a lter S. The container E is suitably mounted in the lower part of the machine. The pump d conveys the oil through a pipe 9 by Way of a so-called idle running slide valve le and through the outflow pipe Il of this slide valve into the pressure pipe line I 2, to which all the control slide valves of the stretching nippers are connected. At the end of the pressure pipe line i2 there is a safety pressure valve I3 of known construction, by means of the small hand Wheel if?, of which the maximum oil pressure in the pipe I2 can be set. The safety valve I3 allows superiluous oil to flow out of the pressure pipe line through a pipe I5 back into the container 6. The pressure in the pipe l2 is checked by the pressure gauge I6.

The piston 2i (Figure 7) of the idle running slide valve id is slidable in the valve chamber I? which can be brought into communication through a connection 9 with the pump 6l, through the outow pipe i! with the pressure pipe I2 and through an outflow pipe Ell with the container E3. The Valve chamber il is provided at the place between the orice of the connection e and the pipe II with a recess i3 which is in the same position as a corresponding recess 2Q in the piston 2l. This piston ZI has at its lefthand end a conical extension 22 provided with ribs 23, against which bears a spring 24 which seeks to force the piston 2i out of the chamber il. The right-hand end of the piston 2i carries a pin 25 projecting from both sides of the piston body 2I (cf. Figure 8) and a roller 26. The piston 2i can be actuated either by a lever operated by the knee of the Worker or automatically by a cam disc by the machine, as will be described later, and has as its main function to enable the pump l to run idle, when, the individual devices being inoperative, no pressure cil is required in the pipe l2. The pressure iluid present in the pressure pipe I2 is prevented from flowing back by a non-return valve E52 loaded by a spring |53.

As already stated, the individual nippers are almost exactly alike in construction and each group of nippers has a common slide valve. It should therefore suffice to describe hereinafter the arrangement of a single group of nippers with the slide Valve belonging to it.

Each nipper forms an independent mechanical unit which is housed in the working cylinder 2l (Figure 2) which is in xed communication with a tubular extension 23. rIhe tubular extension 2% is clamped in an adjustable socket 2Q, by means of which the nipper can be iixed to holders or" a known kind (not shown), which latter can be controlled in a known manner by hand levers, such that each nipper can be displaced with respect to the work, as is, for instance, necessary, when changing over from one kind of shoe or size of shoe to another, or as may seem necessary when stretching the upper over the last. Thus, the tce nipper I is adjustable in the longitudinal axis of the shoe to be made, the side nippers 2, 2 are rockable in the direction of the converging sides of the shoe toe and, in addition, laterally adjustable to diierent distances with respect to the longitudinal axis of the shoe, whilst the ball nippers can be adjusted both in the longitudinal and in the transverse direction to the shoe axis. In the arrangement according to the invention the adjustment of the nippers is rendered very easy compared with the known machines of this kind, since the nippers themselves can be of very light construction, owing to the simple hydraulic drive.

The tubular extension 23 forms the guide for a sleeve Se, to the upper end of which the immovable nipper jaw 3i of the stretching nippers and a pin 32 is xed, about which the rockablc nipper jaw 33 turns. The sleeve 3G is connected by means of a hollow rod 3S which extends through a stufi'ng box 35 of the nut 36 shutting off the upper part of the working cylinder 21, with the hollow piston 31 which has the special form shown in Figures 2 and 3. The transverse partition 38 of the piston 31 is provided with a series of apertures 39 which connect the space 45 in the hollow part of the piston with the space 4| above the piston. On the outside of the transverse partition 38 there is provided a seating for the valve 42 which is displaceable on the threaded part 43 of the piston 31. This valve d2 is pressed against the seating in the transverse partition 38 by a spring 44 which bears against a collar 45 screwed on to the upper end of the threaded part 43.y The casing of the piston 31 is also provided with a number of inlet openings 45.

In the hollow rod 34 a rod 41 is guided, to the lower end of which a piston 48 is xed, which is guided on the inner surface of the piston 31. This piston 48 is provided at both sides with packing rings 49 and at the inner side with a distance sleeve 5| (Figure 3) with apertures 5|). The upper part of the rod 41 has a tubular extension 52 (Figure 2), the forked end 53 of which is provided with grooves 54, in which a pin 55 is slidable, which also co-aots with the guiding slot 55 of the rocking nipper jaw 33 which rocks about the pin 32.

On the rod 41 is also nxed a sleeve 51 which has at both ends inclined surfaces 58 which act against rounded ends 59 of two securing levers 5d, which latter are mounted so as to rock on pins 5| in slots 52 of the sleeve 3|). The manner, in which these securing levers operate, will be explained hereinafter.

1n the fixed tubular extension 28 is a slot 54, in which a pin 35 slides, which is fixed in the sleeve 3e. ln the case of the toe and side nippers this guiding slot 54 is in a straight line, so that the sleeve 3o and with it the nipper jaws 3|, 33 always retain the same axial position during the movement of the sleeve 3|) in the tubular extension 23. ln the case of the ball nippers, however, the slot 64 is curved in the upper part, with the result that, during the movement of the sleeve 3c in the tubular extension 28, an axial turning motion of the sleeve 38 together with the nippers takes place, which corresponds to the curvature of the slot 64.

The working cylinder 21 has three connections for the pressure fluid, namely at the place 5S which opens into the space 4| above the piston 31, a connection 61 opening into the space 43, that is into the space between the pistons 31 and 138, and finally a connection |38 which opens into the space 69 below the two pistons 31 and 48. The end of the working cylinder 21 is closed by a nut |54, the part of which lying within the working cylinder is provided with a reduced portion |55 which extends to about half way across the inlet opening 68. The upper edge of the reduced portion |55 is provided with grooves |53 which allow the pressure fluid to flow through out of the connection 68 under the piston 31, when the latter is in its lowest position, in which it comes up against the reduced portion |55.

The control of the flow of the pressure fluid into the working cylinders 21 of the individual nippers is effected by separate control slide valves, of which one is seen in detail by way of example in Figure 4. The casing of the slide valve is mounted in the machine frame, namely in the lower part of the machine (cf. Figure l) and is provided with three chambers 1|, 12, 13. The chambers 1|, 12 are control chambers and the chamber 13 a reduction chamber. In the chamber 1| acts a piston 14, in the chamber 12 a piston 15 and in the chamber 13 a piston 15. The chambers 1| and 12 are exactly alike, as are also the pistons 14 and 15 associated therewith. The chamber 1| is connected by the inlet 11 with the pressure pipe l2 (according to Figure 1) and is provided on the one hand with an outflow 13 leading to the container 6 and on the other hand with through flow openings 13 and 85. r,The same functions are performed in the case of the chamber 12 by the inflow 3|, the outflow 82 and the discharge openings 83, Sli. rlhe through flow opening is in communication with the reduction chamber 13 and the latter through the opening 86 with the discharge 18. The piston 14 is provided with three recesses 81, 88, 89, of which the recesses 81 and te are connected with one another through the intermediary of the openings 98, 9| and the bore S2, which opens out of the left-hand end of the piston 1Q into the outow part of the chamber 1|. The orifice of the bore 92 'is closed by a valve 33 which is slidable on a rod 94 xed in the bore 82 by the pin 95. The valve S3 is pressed by a spring against its seating, which spring bears against a collar 81 xed to the end of the rod 94. The valve 93 is under only slight spring pressure and has the object of permanently maintaining a pressure uid column within the spaces connected with one another by the recesses 31 and 89, that is, in the discharge ducts 19 and 8|] and in the working cylinder, in order that the working arrangement can be put in operation immediately at any moment. This also prevents the formation of air bubbles and saves the unnecessary conveyance of pressure fluid. The piston 14 is permanently under the pressure of a spring 98 which seeks to hold the piston in the position shown in Figure 4. t the right-hand end of the piston a roller 93 is mounted, which under the action of the spring Q8 follows the track of a drive cam |39 (Figure l). In the body of the piston 14 is fixed a pin |58 which projects out of both sides of the piston body and, in a middle position of the piston 14 engages in a recess of a lever |82 which is adapted to rock freely about a pin |233 Xed in the valve casing. After the pin |89 has engaged in the recess IDI the piston 1.4 is held in it, as long as the lever |82 is not raised. This raising may be effected either by means of a lever |84 which is adapted to be controlled by the worker in a manner to be described hereinafter and acts on a lateral arm |35 or by means of a cam acting on the rounded end of the lever |52.

The piston 15 operating in the chamber is constructed like the piston 14 and its parte, therefore, bear the same reference numerals as those of the piston 14, in so far as they are mentioned. Only the roller |81, the pin |83, the recess |58, the lever H8, the lever the arm l2 and the rounded end |3 have new reference numerals.

The two pistons 14, 15 have altogether three operative positions, of which the right-hand extreme position is seen in Figure 4, the middle position in Figure 5 and the left-hand extreme position in Figure 6.

The reduction of the pressure destined for the nipper pull is provided by the piston 16 in the chamber 13 which is in communication with the through flow opening 80. The piston 16 is sub- "ject to thepressure of 7 a spring I I4, the rvpressure of which c'an`be'regulated'by means ofa small hand wheel (of. Figure 1) over the bevel wheels IE6 and a nut ||8 on the screw |I1, against which nut one end'of the spring H4 bears. The displacement of the piston 16 to the right (see Figure 4) is limited by a pin I 9. The pressure in the conduit behind the reduction valve is checked by a pressure gauge |20 (Figure l) which is connected to the bore |2| opening into the through flow opening all (Figure 4).

For each group of nippers there is a control slide valve. For the toe nipper I is provided the control valve |22 (Figure 1), for the side nippers 2, 2' the valve |23 and for the ball nippers 3, 3 the valve i241. The connection of the individual controlling valves to the groups of nippers is shown in Figure 1 and is preferably by way of flexible tubes. In those'cases, where a single valve controls several nippers, a distributor of a known kind is used, which enablesv the pressure rluid to be distributed from a single outlet to the valve at various operative places. All the groups of nippers are connected to the individual valves in substantially the same manner. It should therefore be sufcient to describe only one of these connections in detail, for instance that of the side nippers 2, 2 to the valve |23.

The outlet opening 19 (Figure ll) is connected by means of a flexible tube |25 (Figure 1) directly with the supply point 68 (Figure 2) of the working cylinder of the nippers 2 and the discharge opening S4 by means of a flexible tube |26 directly with the supply point of the nippers 2. duced pressure prevails, the pressure fluid is conveyed by means of a tube |21 into a distributor E22 of known design and from there through tubes |29 and |39 to the supply points 61 of the nipper 2 and 2', respectively. In the same way the pressure uid is conveyed from the opening S3 through the tube ISI into the distributor |32 and from there through the tube |33 into the supply point 6G of the nipper 2 and the tube |34 into the supply point i of the nippel` 2. In the case of the toe nipper a distributor is not necessary; the discharge opening 80 of the valve |22 can, therefore, be connected directly with the supply point (S1 of the nipper I. The pull of the nipper I is checked by a pressure gauge |35 and the pull cf ball nippers 3, 3 by a pressure gauge I.

The control of the valves is effected in two different ways, on the one hand by the worker by means of a system of levers and on the other l hand automatically by means of cam discs. In Figure l the lever control for the valve |23 of the side nippers 2, 2 is illustrated diagrammatically. This lever control consists of a kneeactuated lever |31 which is capable of rocking laterally about a pivot pin |33. This knee lever 31 is connected by means of a pull rod |39 to a lever arm Ili keyed on a shaft I4I. The shaft ifi! is rotatable in suitable bearings and supports several other keyed-on lever arms, namely the lever arm |42, which acts on the pin 25 (see Figure 1) of the piston 2| of the idle running valve It), and a further forked lever |43, of which one arm |44 acts on the lower part of the pin It) (see Figure 4) and the other arm |45 on the pin I @3, when the shaft IllI is turned in the counter-clockwise direction. The arm |44 is turned somewhat to the left with respect to the arm |45, namely by half the length of the stroke ofthe pistons 14 and 15, which will-be described From the discharge opening Sil, Where re- 'in detail hereinafter. 'also'keyed a forked lever |46, the arms |64 and On the shaft |4| there is I I I of which have already been referred to, which arms act on the pins |05 and I I2 (Figure 4) when the-shaft |4I is turned in the clockwise direction.

The valve |22 is controlled in the same manner,

the larrangement being such that the two valves can be'controlled by means of a single knee lever'ISl, movements of the same forwards and backwards being combined. The ball nippers 3,

I3 and correspondingly theassociated valve |24 are, for reasons explained below, controlled only automatically, namely by vcam discs.

For reasons explained hereinafter the piston 2| (Figure 7) of the idle running valve must'be displaced to the left, even when the control lever |31 is displaced to the right. This action is lbroughtv about, for instance, by an arrangement lindicated in Figure 8, in which lthe lever |42, 2|)

The described arrangement operates in the following manner:

By starting the electric motor 5 the piunp 4 is put in operation, which draws the pressure fluid by suction through a filter 8 out of the container il .and conveys it through a pipe 9 t0 the idle running valve IG. As long as the machine itself is still inoperative, the pump 4 runs without load, as the pressure fluid can return without performing pressure work out of the pump by way of the idle running Valve It back to the container 6. The

piston 2| of the idle running valve I0 at the same time -occupies its right hand eXtreme position, that 1s to say a position which is derived from Figure 7 through the displacement of the piston 2| to the right by the whole length of the recess 2t. The pressure fluid can in this position flow out of the pipe'l through the recess lI9 around the conical extension 22 of the piston and between the ribs 23 into the discharge pipe |8.

The worker then takes up the work and places it in the machine, proceeding in substantially the same mann-er as with the majority of machines of this kind. He first of all inserts the marginal portion of the upper at the toe of the shoe between the jaws of the nipper I, which are in their highest position and are open, as are all the other nippers. By swinging aside the knee lever |31 (Figure l) he causes by means of the control valve |22 the closing of the toe nipper which clamps the upper, so that he is enabled to stretch it tightly in a suitable manner in the 1ongtudinal axis of the last. He thereupon inserts the marginal portions at the side of the upper into the side nippers 2, 2 and, after forcing down the last against a support of a known kind (not shown), he closes the jaws of the nippers 2, 2 as well by swinging the knee lever |31 to the left, so that the upper can be tightly stretched at the sides as well. The upper is only gripped by the ball nippers and stretched tightly in the ball part of the last, when the Worker has made sure that I the upper has been correctly pulled vover both at the toe and at the sides. As the ball nippers can no longer substantially influence the correct stretching over of the upper gripped and held by the toe and side nippers, it is not necessary for the ball nippers to be controlled by the worker himself, so that in the constructional example illustrated this is effected only automatically from the cam shaft |41.

Before the commencement of the operation, as already stated, all the nippers are open and the toe nipper I as well as the side nippers 2, 2 are in their uppermost position. The ball nippers 3, 3 may be positioned somewhat lower, so vthat they will not be in the way, when the marginal portion of the upper is being inserted in the other nippers, and only, when the upper is to be inserted in the ball nippers, are the latter raised. Before the commencement of the operation the actuating device of each of the nippers occupies the position shown in Figure 2, whilst the two pistons 14, of the associated control valve according to Figure 4 are still, from the previous operation, under the pressure of the space 69 of the working cylinder 21 (Figure 2) of the nippers, as they are in communication through the tubes |25, |23, the discharge openings 18, B4, the recesses 83 and the inlets 11, 8| with the pressure pipe l2 (Figure 1). Both pistons 31 and 48 of the nippers are in their uppermost positions. since both spacesy 4i! and 4i (Figure 2) are without pressure, as they are in communication by way of the associated conduits with the discharge openings 80 and 83 which are connected by way of the recess 61, the opening Qt, the bore 92 and the valve 93 with the

discharge pipes

18 and 82.

As soon as the worker has inserted the marginal portion of the upper between the opened jaws 3 33 of the nippers, he causes by swinging the knee lever |31 (Figure l) to the left the gripping and stretching of the upper part until the nippers come to rest in the tensioning motion. Through the lever |31 being swung to the left the shaft I4! is caused to rotate and the levers |42, |43 and |146 fixed on it are also caused to swing to the left. During this swinging motion, however, only the levers M2, |43 come into operation, the action of which corresponding to their inclination is so distributed in respect to time that the lever |42 comes into action on the pin of the piston 2| of the idle running valve at the same time as the arm |44 of the lever |43 comes into action on the lower part of the pin |90 of the piston 14 oi the control valve, whilst the arm |45 of the lever |43 only comes into action later on the pin |03 of the piston 15, the retardation with respect to the longitudinal dimensions amounting to half the stroke of the piston i4. The lever |42 pushes the piston 2| of the idle running valve into the left hand extreme position shown in gure 7, in which the discharge of the pressure fluid into the discharge pipe I8 is shut ori and the way into the pressure pipe i2 is laid open, the pressure fluid opening the non-return valve |52 itself. The piston 14 of the control valve moves under the action of the arm lili of the forked-lever |43 into its left hand extreme position according to Figure 6, whilst the piston 15 under the influence of the arm |45 occupies a middle position a-ccording to Figure 5. rThe result oi this is, that the pressure uid passes out oi the pressure pipe l2 through the inlet 11 and the recess 38 into the discharge opening 8D, to which the reduction chamber 13 is connected, in which the pressure is reduced as required, corresponding to the adjustment of the spring I I4 by the hand wheel I5, any superiiuous pressure fluid forcing the piston 1S back and escaping through 10 the opening 86 into the discharge 18 (Figure 4) The pressure iluid passes with reduced pressure through the discharge opening 82 and the associated conduits into the iniiow opening 61, that is into the space 4i! according to Figure 2. At the 'same time the pressure fluid escapes from the space 69, which was hitherto under pressure through the associated conduits into the openings 19 and 84 and from the latter only through the opening 19 which is connected with the opening 34 by the communicating bore 35, into the recess 3d of the piston 14 and from there through the opening 9|, the bore 92 and by way ofthe valve 33 into the discharge 18. In this working phase the pressure fluid cannot pass directly through the opening 34 into the discharge pipe S2, as long as the piston 15 occupies the said middle position according to Figure 5, in which both the inflow 3| and the discharge openings 83 and 84 are closed. As has already been stated, the pressure fluid has the possibility of passing out of the opening B4 through the communicating bore 85 into the discharge, during which the spaces connected with the discharge opening lose the pressure,

- it is true, but remain iilled with pressure iiuid,

which is brought about by the spring-loaded valve d3. It follows, that, as soon as pressure iiuid reaches the space 40 of the working cylinders of the. nippers, there will in the rst instance be a displacement of the piston 43 downwards (according to Figure 2 obliquely downwards to the right), so that the piston 48 will occupy the position shown in the upper half of Figure 3. At the same time the piston 48 will carry along with it the rod l1 with the forked tubular extension 52 and the pin 55 which slides in the slot 53 of the movable nipper jaw 33 and turns the latter about the pin 32 in such a manner that the said jaw is caused to bear against the xed nipper jaw 3|, thereby clamping the marginal portion of the upper. rlhe closing of the nipper jaws prevents the possibility of any further displacement of the rod 41 and the piston 48 downwards, the pressure in the space lil begins to rise, until it exceeds the force of the spring loading the valve 42, opens this valve and causes pressure fluid to begin to 'flow through the openings 39 in the transverse partition 38 into the space 4 as can be seen from the lower half of Figure 3. As long as the inflow opening G6 in the space 4| remains blocked by the piston 15 of the control valve, as stated above, the pressure in the space 4| will act on the entire surface of the hollow piston 48 and commence to force this piston 48 together with the piston 31 further downwards (according to Figure 3 to the right), until both pistons reach the position shown in the lower part of Figure 3. During this combined displacement of the pistons 31 and it the tubular extension 28 together with the nipper jaws 3|, 33, between which is the clamped marginal portion of the upper, is also carried along and the upper is stretched over the last. The pressure in the now connected spaces 46 and 4i rises in proportion to the resistance olered by the upper to being tensioned, causing not only the pull of the nippers to increase, but also the gripping force of the nipper jaws 3| and 33 against one another. The pressure in the spaces dit, 4| continues to rise, until it reaches its maximum value determined by the reduction piston is, whereupon the further pulling motion of the nipper ceases.

When the worker desires to reach the maximum pull of the nippers as quickly as possible, he holds the knee lever |31 in its left hand position, until the pulling motion of the nipper ceases. As soon as the worker releases the knee lever |31, it will return automatically under the action of the spring 24 of the idle running valve into the initial position, when the piston 2| will also be displaced into the right hand extreme position, the pin of the piston 2| carrying the lever |42 of the shaft |4| along with it. The worker will, however, not always utilize the full reduced nipper pull, but, should a weak upper part make this necessary, will allow the pull to increase step by step, by alternately displacing the knee lever |31 to the left and releasing it again and thereby interrupting and restarting the pulling motion of the nippers which he can repeat over and over again, until the upper is correctly stretched over the last.

As has been just explained, the knee lever |31 returns each time it is released automatically into the initial position and the control piston 2| of the idle running valve I0 occupies its right hand eXtreme position, in which the inflow of the pressure fluid into the pressure pipe I2 is blocked. Owing to the fact that the knee lever |31 returns into the initial position, the forked lever |43 also moves away from the pistons lf3 and 15 of the control Valve and these two pistons seek under the action of the springs S3 also to return into their initialrposition, that is, into the right hand extreme position. This is, however, prevented by the levers |02, H0, in the recesses |0I and |09 of which the projecting pins |00 and |08 have already engaged. IThe recesses I0| and |00 thus hold both pistons 14 and 15 in the middle positions according to Figure 5, in which both the inflow and the outflow openings of the control valve are closed. Through the release of the knee lever |31, which has been swung aside, a blocking of the entire working arrangement of the nippers is thus brought about in 'the position in which the nippers happened to be at the moment of release of the knee lever. Each time the knee l-ever |31 is again swung to the left, only the piston 14 is displaced to the left in the control valve, until it reaches, say the lefthand extreme position again (the piston 15 remains in its middle position, in which it had already been set after the 'lrst swinging aside of the knee lever) and a renewed action of the pressure fluid takes place in the spaces 40 and 4| of the working cylinder of the nipper, so that the increase in pressure in these spaces progresses up to the eventual maximum value.

In the case of an incorrect gripping and stretching of the upper over the last it is possible to release the upper again from the nippers and to set the whole arrangement back into the initial position, by swinging the knee lever |31 in the opposite direction, that is to the right, when the arms |04 and III of the forked lever Ille` will strike against the pins |05, I |2 of the levers |02, ||0 and raise them, whereby the pins |053 and |08 are brought out of engagement with the recesses IDI, |09 of these levers and the pistons 14, 15 of the control valve return under the influence of the springs 98 into their right hand extreme position shown in Figure 4, in which both spaces 40 and 4| of the nippers are connected to the discharge. As, however, on the knee lever |31 swinging to the right as well, the idle running arrangement is blocked, that is to say, the piston 2| of the idle running valve I0 is forced into the left hand extreme position according to Figure '7, in which the inflow of the pressure fluid into the pressure pipe I2 is set free,

thezfluidwill flow through the supply conduits 11 and 8| by way ofthel recesses 88 of the pistons 14, 15 and through the openings 19, 84 and the associated flexible tubes into the spaces 69 of the working cylinders 21 of the nippers, so that the two pistons 31 and 43 of the latter will return into their upper position shown in Figure 2, the nippers opening and moving upwards.

In addition it is also possible to correct the position of the upper which has already been gripped by the nippers and put under tension by them by adjusting individual nippers in their cl-osed state with respect to the shoe support, which may be effected byA means of a system of levers of a known kind (not shown), which act on the outer socket 29 of the working cylinders of the nippers.

The case may also occur, in which the upper is incorrectly placed between the still open nipper jawsand, although the latter close, they do not grip the upper and perform the pulling motion, While empty. Since in this case the motion of the nippers encounters no resistance, it might occur that both pistons 31 and 48 will move downwards until they strike against the reduced portion |55 of the closing nut |54 of the working cylinder 21. The samevthing might occur if the nippers, although Icorrectly gripping the upper, should tear it away when tensioning it. For this reason the rod 41 is provided with the sleeve 51 with bevelled end surfaces which, on. the nipper jaws 3|, 33 closing, mount the rounded ends 59 of the safety levers 60, causing the latter to move apart. A downward movement of the nippers to the aforesaid stop is thereby prevented, as the ends of the safety levers B0, through projecting out of the sleeve 30, strike against the end surface 63 of the tubular extension 20 and thereby render a further downward movement of the nippers into the undesired position impossible.

The ball nippers 3, 3' which during the whole of the time occupied by the preparation of the upper, While being inserted into the nippers I, 2 and 2', are released and are brought into the uppermost position according to Figure 2 through the admission of pressure fluid into the space 63.

With the stretching of the upper over the last by the point and side nippers the first phase of the operation of the machine is finished. The second phase is now initiated, which is characterised by the automatic running of the machine.

The marginal portion of the upper is inserted between the opened jaws of the ball nippers 3, 3 and, through throwing in a coupling, the cam shaft 41 is put in rotation, the cams of which perform the function of controlling the work of the nippers during the further operation, by causing through the intermediary of the control valves the pressure fluid to flow out of the pressure pipe into the working cylinders. On the shaft |41 being started up, in the first place by means of the cam |5| acting on the roller 26 of the piston 2| the idle running motion is blocked and the pressure pipe thereby connected with the pump, the control valve |24 being at the same time put into operation by means of further cams, similarly as previously by means of the knee lever |31, such that the ball nippers 3, 3' are caused to close, to grip the marginal portion of the upper and, at the same time turning axially in the manner already described, to stretch the upper in the ball region of the shoe over the last. After these nippers have completed the pulling motion, the pistons 14 and 15 V 13 of the control valves of all the nippers Will be in the middle positions according to Figure 5.

At this moment, that is to say, when the stretching operation of the upper on the last is finished, the further devices of the tacking machine are put into operation, for instance a toe form (not shown) of a known construction, which presses the upper at the toe against the last and thus secures it against displacement or loosening of the tension after its release from the nippers, which release must take place, in order that the pushing over members of a known kind (not shown) and iinally the nailing or sticking and pressure applying device for iinish tacking the upper can come into action. it is therefore not enough for the nippers merely to open and release the marginal portion of the upper, they must also move downwards some distance, in order that they shall not be in the Way of the further working devices referred to.

The opening of the nipper jaws and the consequent release of the upper is effected by the cams |49 and |55 which in the rst place by acting on the rounded ends |06 and H3 of the levers |52, Il!! raise the latter and bring the pins |011 and |08 out of engagement with the recesses IUI, |09. The cam |43 enables the piston 14 under the influence of the springs 98 to return into the right hand extreme position (ci. Figure 4), Whilst the cam |55 leaves the piston 15 in the middle position (ci. Figure 5). In these positions of the pistons 14, 15 the spaces 4i! of the working cylinders of the nippers are in communication through the inlet openings 45 (Figure 3) with the supply conduits 61 and byV way of the associated iieXible tubes with the discharge conduits 80 of the control valves and these openings in addition by way of the recesses 31, the openings 90, the bores 92 and the valves 93 with the discharge. The result of this is that the pressure in the space 45 drops, whilst the pressure in the space 4| still remains constant, since before the pressure equilisation in the spaces 4E), 4| have been brought about, 4the nonreturn valve 42 under the action of the spring 44 has blocked the connection between the spaces 45 and 4|. At the same time as the spaces 4l) are connected to the discharge opening the spaces 69 are connected to the inlet for the pressure iiuid, namely in the manner already described, so that through the pressure arising in the spaces C-B the pistons 48 are displaced with respect to the pistons 31 upwards (according to Figure 3 to the left). During motion of the piston 48 the pin 55 oi the rod 41 moves in the slot 55 of the nipper jaw 33 forwards and swings the latter into the open position shown in Figure 2, thus causing the upper to be released from the nippers. rl'he piston 31 of the nippers can for the time being not yet move upwards, as pressure is still present in the space 4| above this piston. During the motion of the piston 48 upwards with respect to the piston 31 the safety levers 6!) re-occupy their original position according to Figure 2, that is to say, they fall back into the grooves 52 and nothing more stands in the way of the eventual pushing back of the sleeve 30 together with the nippers, now open, downwards, so that the piston 31 can move downwards until it' strikes against the reduced part |55 of the closing nut |54 at the bottom of the working cylinder 21.

After the release ci the upper by the nippers, it is necessary for the latter to be immediately displaced somewhat downwards, in order that they shall not be in the way of the pushing over members and the fixing devices for the marginal portions of the upper. The downward movement of the opened nippers is produced by the cams i453 and |50, through the piston 14 being forced into the middle position (Figure 5) and the piston 15 into the left hand extreme position (Figure 6). The result of this is, that the opening 85 connected with the spaces 40 and the opening 85 of the distributor valve is closed, whilst pressure fluid passes through the inlet 8| into the chamber 12 of the piston 15 and flows through the recess 58 of the piston 15 to the discharge opening 8 and thence through the associated flexible tubes into the spaces 4| above the piston 31. From the spaces 69 below the piston the pressure fluid flows down into the discharge, as these spaces 69 are in communication through corresponding conduits with the opening 84, the bore 85, by way of the recess 89, the openings 9|, the bore 92 and through the valve 93 of the piston 15 with the discharge pipe 82. Consequently, the pressure uid in the space 4| forces both pistons 31, 48 downwards (that is, according to Figure 3 to the right), until the downward movement of the nippers is brought to an end through the piston 31 coming against the reduced part |55 of the closing nut |54 at the bottom of the working cylinder 21.

After all the operations of the tacking machine have come to an end, the cams |45 and E55 nally cause the return of the opened nippers into the original position through the two pistons 14, 15 of the control valve allowing the return into the right hand extreme position according to Figure Il, in which the spaces 40, 4| are connected to the discharge, whilst the pressure fluid flows in the manner already described through the slots |56 in the reduced portion |55 of the closing nut |54 at the bottom of the working cylinder 21 into the space 69 below both pistons 31, 45 and displaces these two pistons into the initial position shown in Figure 2.

After the return of the nippers into the initial positions the work of the machine is nished and a special coupling, after the cam shaft 14| has performed one revolution, automatically disconnects the drive of the latter.

We claim:

1. A shoe making machine comprising a system of stretching nippers for stretching the upper part of shoes over a last, means for alternately opening and closing the stretching nippers including an hydraulic cylinder with opposed differential pistons therein connected to the stretching nippers for opening and closing the latter to perform pulling and return motions, a spring loaded bypass valve associated with one of said pistons and controlling the flow of huid from a chamber between the pistons, the diiierential pistons cooperating in such a manner that during the stretching motion of the nippers the tractive force of the nipper jaws increases in the ratio of the increasing resistance of the upper to a definite maximum value, the closing force of the nipper jaws increasing at the same time to a corresponding extent.

2. A shoe-making machine comprising: a system of stretching nippers for stretching the upper part of a shoe over a last, each nipper having a xed jaw and a pivoted jaw, means for alternately opening and closing the stretching nippers and for causing the stretching nippers to perform pulling and return motions, said latter means including a hydraulic working cylinder,

a hollow piston slidable in the cylinder and supporting the fixed nipper jaw, and a piston slidably mounted within the hollow piston and connected with the pvoted nipper jaw, these hydraulic members co-operating in such a manner that during the stretching motion of the nippers the tractive force of the nippers increases in the ratio of the increasing resistance of the upper up to a definite maximum value, the closing force of the nipper jaws increasing at the same time to a corresponding extent.

3. A shoe-making machine comprising: a system of stretching nippers for stretching the upper part of a shoe over a last, each nipper having a iixed jaw and a pivoted jaw, means for ternately opening and closing the stretching nippers and for causing same to perform pulling return motions, said latter` means including a hydraulic working cylinder, a hollow piston slidable in the cylinder and supportinfT the fixed nipper jaw, a piston slidably mounted uthin hollow piston and connected with the pivoted er jaw, a transverse partition in the hollow and a by-pass valve provided in the said partition, connecting a space above the hollow piston with the space between the two working pistons, these hydraulic members co-operating in such a manner that during the stretching motion of the nippers the tractive force of the nippers increases in the ratio of the increasing resistance or the upper up to a denite maximum value, the closing force of the nipper jaws increasing at the saine time to a corresponding extent.

4. A shoe-making machine, comprising: a l tem of stretching nippers for stretching the upper part of a shoe over a last, each having a fixed jaw and a pivoted jaw, means for alternately opening and closing the stretching nippers, and for causing same to perform pulling and return motions, said latter means including a hydraulic working cylinder, a hollow iston slidable in the cylinder and supporting the xed nipper jaw, a piston slidably mounted within the hollow piston and connected with the pi-voted nipper jaw, the working cylinder being 'formed with three openings for the admission of pressure fluid, one of which admits it above the hollow piston, one between the two wort-.ing pistons, and one below the pistons.

5. A shoe-making machine, comprising: 'ein of stretching nippers for stretching the upper pai-tof a shoe over a last, each nipper having a xed jaw and a pivote-:l jaw, means for alternately opening and closing the stretching nippers and for causing the stretching nippers to perform pulling and return motions, said latter means including a hydraulic working cylinder,

hollow piston slidable in the cylinder and supporting the ixed nipper jaw, a piston slidably mounted within the hollow piston and connected with the pivoted nipper jaw, the opening and closing of the nipper jaws being eiected by a relative displacement of the two pistons that are guided one within the other, caused by pressure fluid being admitted into or discharged from the space between the two pistons, these hydraulic .iembers co-operating in such a manner that during the stretching motion of the nippers the tractive force of the nippers increases in the ratio of the increasing resistance of the upper up to a definite maximum value, the closing force oit' the nipper jaws increasing at the saine timV to a corresponding extent.

6. A shoe-making machine comprising: a system of stretching nippers for stretching the upper part of a shoe over a last, means for alternately opening and closing the stretching nippers and for causing the stretching nippers to perform pulling and return motions, said latter means including a hydraulic working cylinder, a hollow piston slidable in the cylinder and supporting one nipper jaw, a piston slidably mounted within hollow piston and connected with the other nipper jaw, a spring-loaded by-pass valve connecting a space above the hollow piston with the space between the two working pistons, so that upon pressure iiuid being admitted into the space between the two working pistons the pressure in this space, which rises after the closing of the nipper jaws, opens the by-pass valve, enters the space above the hollow piston, and from there acts on both working pistons simultaneously, thereby forcing both pistons downwards and exerting a tensile stress on the work.

7. A shoe-making machine comprising: a system of stretching nippers for stretching the upper part of a shoe over a last, means for alternately opening and closing the stretching nippers and for causing the stretching nippers to perform pulling and return motions, said latter means including a hydraulic working cylinder, a hollow piston slidable in the cylinder and supporting one nipper jaw, a piston slidably mounted within the hollow piston and connected with the other nipper jaw, the opening and closing of the nipper jaws being eiected by a relative displacement of the two pistons that are guided on@ within the other, caused by pressure fluid being admitted into or discharged from the space between the two pistons, and a spring-loaded by-pass valve connecting a space above the hollow piston with the space between the two working pistons, these hydraulic members co-operating in such a manner that the closing force of the nipper jaws before the initiation of the tensioning motion of the nippers is dependent upon the spring loading of the by-pass valve, whereas during the stretching motion of the nippers the tractive force of the nippers increases in the ratio or" the increasing resistance of the upper up to a dennite maximum value, the closing force or" the nipper jaws increasing at the Same time to a corresponding extent.

8. In a shoe-making machine as claimed in claim 1, two working chambers and pistons therein constituting a' single slide valve for controlling several nippers which operate in the same manner as regards the motion and time phases, a system of manually operated levers for actuating the pistons, and cams whereby the machine operates the pistons automatically.

9. In a shoe-making machine as claimed in claim 1, two working chambers and pistons therein constituting a single slide valve for controlling several nippers which operate in the same manner as regards the motion and time phases, and a control lever for so adjusting the pistons of the slide valve as to eiect the closing and the pulling motion of the said nippers by admitting pressure fluid into the space between the differential pistons of the hydraulic cylinder and opening a space beyond these pistons to exhaust, the arrangement being such that the operation of the nippers can be interrupted by means of the control lever at any desired moment and the nip-pers fixed in their momentary position or returned immediately into their initial position.

l0. In a shoe-making machine as claimed in claim 1, two working chambers and pistons therein constituting a single slide valve for controlling several nippers which operate in the same manner as regards the motion and time phases, a control lever for so adjusting the pistons of the slide valve as to eiect the closing and the pulling motion of the said nippers by admitting pressure iluid into the space between the diierential pistons of the hydraulic drive and opening a space below these pistons to exhaust, and safety elements for holding both pistons of the slide valve in positions in which pressure uid does not flow either into or out of the hydraulic driving means of the nippers, the arrangement being such that the operation of the nippers can be interrupted by means of the control lever at any desired moment and the nippers xed in their momentary position or returned immediately into their initial position.

11. In a shoe-making machine as claimed in claim 1, two working chambers and pistons therein constituting a single slide valve for controlling several nippers which operate in the same manner as regards the motion and time phases, a control level for so adjusting the pistons of the slide valve as to effect the closing and the pulling motion of the said nippers by admitting pressure fluid into the space between the differential pistons of the hydraulic drive and opening a space lbelow these pistons to exhaust, safety elements for holding both pistons of the slide valve in positions in which pressure fluid does not ow either into or out of the hydraulic driving means of the nippers, springs for returning the pistons of the slide Valve intotheir initial positions after the release of the safety elements, and thereby putting a space above the differential pistons of the nippers and also the space between motion and time phases, a system of manually operated levers for actuating the pistons of the slide valve, and cams that come into operation automatically when the actual operation of stretching the upper over the last by means of the nippers is nished, these cams then effecting the opening of the nipper jaws to release the ,marginal portion of the upper, Ithe evasive motions of the nippers downwards, and the return of the open nippers into the initial position.

JOSEF1 ZAORAL.

VILE'M os'rRIL.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 702,098 Pickle July 8, 1902 1,232,701 Aiken June 15, 1920 2,225,639 Keall et al. Dec. 24, 1940 Y2,324,509 Jorgensen July 20, 1943 2,392,423 Stephens Jan. 8, 1946 2,423,454 Jorgensen July 8, 1947