US3911703A

US3911703A - Machine for processing skins or hides

Info

Publication number: US3911703A
Application number: US489939A
Authority: US
Inventors: Silvio Repetto
Original assignee: Luigi Rizzi and Co SpA
Current assignee: Luigi Rizzi and Co SpA
Priority date: 1973-08-08
Filing date: 1974-07-18
Publication date: 1975-10-14
Anticipated expiration: 1992-10-14
Also published as: DE2437891A1; FR2240291B1; CS176282B2; FR2240291A1; GB1444850A

Abstract

The invention provides a device in a skin treating machine for holding a skin against the knives of a rotating cylinder to enable the latter to perform an accurate skiving operation. It includes a bolster which urges the skin against the knives and extends the full width of the cylinder. The bolster is made of thick rubber, and is supported at several points on a main beam by local screw-operated adjusters. The whole beam is mounted on levers which are hydraulically operated to bring the beam and bolster up to the skin and hold it against the knives. Further automatic adjustment is also provided to accommodate local variations in skin thickness.

Description

Oct. 14, 1975 MACHINE FOR PROCESSING SKINS OR RIDES [75] inventor: Silvio Repetto, Modena, Italy [73] Assignee: S.p.A. Luigi Rizzi & C., Modena,

Italy [22] Filed: July 18, 1974 [21] Appl. No.: 489,939

[30] Foreign Application Priority Data Aug. 8, 1973 Italy 27652/73 June 18, 1974 Italy 24081/74 [52] US. Cl. 69/37 [51] Int. Cl. C148 l/l4 [58] Field of Search 69/37, 42

' [56] References Cited UNITED STATES PATENTS 1.053.297 2/1913 Kehrhahn 69/37 2.038.621 4/1936 Whitney 69/37 X 2,638.769 5/1953 Gianoglio 69/42 2,674.1 14 4/1954 Brill et al. 69/42 3,276,230 10/1966 Horn 69/42 3,789,632 2/ 1974 Repetto 69/42 FOREIGN PATENTS OR APPLlCATIONS I 513.271 11/1930 Germany 69/37 155.348 12/1920 United Kingdom 69/37 158,503 6/ 1922 United Kingdom 69/37 Primary Examiner-Alfred R. Guest [57] ABSTRACT The invention provides a device in a skin treating machine for holding a skin against the knives of a rotating cylinder to enable the latter to perform an accurate skiving operation. it includes a bolster which urges the skin against the knives and extends the full width of the cylinder. The bolster is made of thick rubber, and is supported at several points on a main beam by local screw-operated adjusters. The whole beam is mounted on levers which are hydraulically operated to bring the beam and bolster up to the skin and hold it against the knives. Further automatic adjustment is also provided to accommodate local variations in skin thickness.

9 Claims, 10 Drawing Figures US. Patent Oct. 14, 195 Sheet 1 of4 3,911,703

US. Patent Oct. 14, 1975 Sheet 2 of4 3,911,703

Sheet 3 of 4 U.S. Patent Oct. 14, 1975 I MACHINE FOR PROCESSING SKINS OR HIDES PRIOR APPLICATIONS In Italy dated 8th August 1973 and numbered 27652 A/73.

In Italy dated 18th June I974 and numbered 24081 A/74.

The present invention concerns a machinefor pro cessing skins or hides and, in particular, a device for resiliently supporting a skin being processed against the action of the operating tool so as to remove-only the surface layer, with the possibility of varying the treating thickness where necessary and without having to confine treatment to only one thickness of skin.

As is well known, tanning machines and, in particular, those adapted to the defleshing of'skins, generally include a tool shaped like an operating cylinder, rotating in a fixed position, and provided with blades or other types of tools or abrasive surfaces, and conveyor rollers for feeding the skins.

The conveying rollers are motor-driven and comprise a rubber-covered cylinder over which the skin is extended, and two feeding rollers of steel with knurled surfaces, which press the skin against the rubbercovered cylinder, thus effecting the feed movement thereof.

The bladed cylinder for removing the flesh from the inner side of the skin, works against a resilient bolster forming part of the support device which, in conventional machines, is a solid or hollow rubber cylinder, mounted on a beam parallel to the bladed cylinder and locked between upper and lower jaws which leave only a small arc exposed which comes into contact with the skin.

The rubber cylinder is urged against the skin to a predetermined position based on the average thickness of the skin itself; however, in view of the considerable local differences in the thickness ofa skin, such as cowhide, the elasticity of the rubber cylinder is not sufficient to absorb the variations in thickness, for which purpose the lower jaw is generally divided into sectors, each of which is separately adjustable and subjected to the action of resilient means.

This known device for supporting the skin has many disadvantages, the first of which is possible damage to the outer surface caused by accidental contact with the bladed cylinder. In this case it is necessary to vary the position of the rubber cylinder between the metal jaws in order to place an integral portion of the cylinder itself in contact with the skin being processed, this operation being possible only for a limited number of times both for the variation in diameter which the rubber cylinder assumes and for the differential engagement between the metal jaws, due to variation in shape, with consequent insufficiency of projection of the support cylinder towards the jaws themselves.

If the support cylinder is hollow and kept under pressure by compressed air, the disadvantage of accidental contact with the bladed cylinder is even greater on account of the possible bursting of the support cylinder resulting from superficial damage.

A second series of disadvantages inherent in known devices is due to the means for controlling and spring mounting the various parts which have to be used.

These disadvantages reside substantially in the possibility of the means becoming locked on account of inerustations and corrosions forming as a result of the presence of the chemical substances with which the skins are washed in the course of processing.

These serious disadvantages are eliminated by the skin supporting device of the present invention, which involves no loss of time in replacement or rotation of the support bearing and eliminates the need to use pneumatic means for supplying the required elasticity thereof.

According to the present invention there is provided a device in a skin treating machine for the resilient support ofa skin having variations in thickness, comprising a beam displaceable relatively to an operating cylinder, on which beam there is mounted on plane guides a resilient bolster transversely adjustable by adjusting units located at regular spaced intervals over the entire length of the bolster so as to cause the bolster to assume a transverse line best adapted to the thickness of the skin being processed, and hydraulic means for setting the basic treatment thickness and for increasing this thickness in accordance with the dimensions of the skin. 1 I

The elastic bolster has a substantially parallelopiped shape, and may have reduced portions, longitudinal outlets or grooves for the purpose of increasing its elasticity in a transverse direction, and is preferably provided in the rear portion with a flexible metal strippermitting connection with the position adjusting units.

According to one embodiment, the elastic rubber bolster may have one or more series of vertical, cylindrical, transverse holes distributed over its length and towards the rear end of the bolster. The holes may be provided with longitudinal outlets or channels both in the parallelopiped bolster of a single material, and in combination with the reduced portions, and also in combination with layers of different elasticity.

The vertical holes may be distributed uniformly over the entire length of the bolster or grouped in predetermined areas of the bearing, or distributed variously over the length, particularly where the horizontal thrust is applied by the means adjusting the position and the distance.

Said vertical holes have the purpose of permitting variation in the transverse elasticity of the bolster, both in relation to their dimensions and their distribution, and plugs of more or less elastic or rigid material maybe introduced into all or some of the holes, thus permitting further variation in the elasticity of the bolster corresponding to zones of the skin being processed, in which there are normally appreciable variations in thickness.

The plugs may partially or completely fill one or more holes. The holes themselves may also have shapes differing from the cylindrical, and may be elongated or elliptical.

The position adjusting units are formed by means capable of transversely displacing the elastic bolster, and may comprise externally controlled male and female screw means for locking in position, or by hydraulic means for obtaining small displacements and representing a fixed support point for the rear part of said parallelopiped elastic bolster.

The elastic support device comprises, as stated, a beam which is transversely displaceable and the movement of which is determined by hydraulic means interposed at the ends between the cross-piece and the opening and closing levers of the machine; the means may include piston and cylinder units controlled by.

valves which are in turn adjusted by screw means actuated by a hand wheel for adjusting the thickness of the skin. Alternatively, the thickness may be varied, by means of the hydraulic units, relatively to the thickness of the skin, the requirements of the processing and/or the wear on the blades and/or on the bolster, by control means operating the hydraulic valves which control the positioning units located at the ends of the beam.

With the device of the present invention, in addition to eliminating the disadvantages of solid or hollow rubber cylinders having a pneumatic action, it is possible to obtain both faster and more precise processing due to the resilient bolster, which does not require replacementor adjustments, and which provide more economical processing since the control means are not subjected to incrustations and corrosions, only the elastic parallelopiped being exposed, this is slidable between the plane guides of the beam, whilst the rear control units are completely protected and hermetically sealed.

These and other features will become apparent from the following detailed description of an embodiment of a skin supporting device according to the present invention, illustrated in the accompanying drawings, in which:

FIG. 1 shows a front view of a defleshing machine including the device;

FIG. 2 shows a cross-section through the machine, taken on line IIII of FIG. 1;

FIG. 3 shows on a magnified scale the details of the central part of the section taken on line II-II;

FIG. 4 shows a perspective view of the machine;

FIGS. 5 9 show various embodiments of the elastic bolster in cross-section; and

FIG. shows an elastic bolster with a plurality of holes, located in the working position relatively to the bladed cylinder in the defleshing machine.

FIGS. 1 and 2 show the defleshing machine as a whole. It comprises two sides 2, 3 connected at the bottom by a base 1 and at the top by a beam 4, in which framework a bladed cylinder 5 is mounted and driven to rotate by a suitable motor.

Supported on the sides 2, 3 are two levers 6, 7 pivoted at 8; they are controlled by connecting rods 9 and cam 10 so as to be movable along an arcuate slot 11. At the upper end, each lever supports a driven roller 12 with a rubbercovered surface for supporting a skin during processing.

A second pair of levers l3, pivoted on the beam 4, supports a driven conveyor roller 14 and is urged to bring roller 14 into contact with roller 12 by pressure cylinders 15. Another pair of levers l6 pivoted on beam 4, supports a second driven conveyor roller 17 and is urged to bring roller 17 into contact with roller 12 by pressure cylinders 18.

A beam 19, extending between the two levers 6, 7, is displaceable horizontally on brackets 20, 21 (FIGS. 1 and 4) connected to the levers 6, 7 by hydraulic pistons 22a, 22b, 23a 23b and held in a stable position by valves 34, 35 the slides 34a, 35a of which are adjusted by means of

gear units

24, 25 connected together by a shaft 26 rotated by a hand wheel 40. The

units

24, 25 are connected to the levers 6 and 7 and to the slides 34a, 35a.

On the upper part of the displaceable beam 19 there are plane parallel guides 27, between which there is interposed a resilient bolster 28 of rubber or like substance, having a substantially parallelopiped shape and capable of sliding between the guides 27. The resilient bolster 28 is connected to a flexible metal belt 29 at its rear end and thus connected to a plurality of uniformly spaced control units along the beam 19, each comprising a threaded shaft 30 which screws on a bush 3] and is externally rotatable by a hexagon end 32. The.interior of each control unit is sealed by suitable seals and known means are provided for preventing unscrewing of the bush.

The resilient bolster 28 projects from the guides 27 towards bladed cylinder 5 and is located, with the machine closed, radially relatively to the bladed cylinder.

The cross-section of the resilient bolster may be seen in FIG. 5; it may be divided into more than one part and extends the entire length of the bladed cylinder 5.

The composition of the bolster 28 must allow sufficient elasticity for absorbing normal variations in the thickness of the skin being processed and, for this purpose, it is possible to shape it with a rear reduced portion, as shown in FIG. 6, and also to construct the block in two parts 28a and 28b using materials of different hardness and elasticity so as to increase the total elasticity of the bolster itself in the direction of the thrust, which is in the direction of the arrow Z.

According to the variant shown in FIG. 7, vertical transverse holes 50 are provided in the bolster 28, in the rear part thereof, the holes having dimensions, shapes and distribution so as to permit an appreciable variation of elasticity in the direction of the thrust of the skin being processed, i.e. horizontally, as shown by the arrow Z.

With reference to the embodiment shown in FIG. 8, the bolster is formed in two parts 28a 28b with materials having different hardness and elasticity. In one of the parts 28b, a longitudinal groove 28c is formed, with a plurality of vertical transverse holes 50 distributed longitudinally. The holes may have different diameters and shapes, and may be disposed in different positions.

The longitudinal distribution of the holes 50 in the bolster 28 may be effected in any order, either with uniform spacing, or grouped in specific zones of the bolster, as shown in FIG. 10, the zones corresponding with each other and coinciding with control units on which the rear end of the bolster is supported, each control unit being adjusted by its hexagon end 32. The presence of the holes 50 permits greater elasticity of the bolster 28 near the rear supports in order to equalise the elasticity of the bolster 28 and the associated metal strip 29 in the spaces between one of the supports and the next. In each case the elasticity of the bolster may be subsequently varied as desired; for example, the bolster with the plurality of holes may have plugs 51 introduced into some or all of the holes, as shown in FIG. 9, the plugs being made of any suitable elastic or rigid material, and playing a part both in longitudinal distribution and in elasticity or hardness, in the total elasticity of the bolster.

The above-described resilient support device, composed of the beam 19 and the resilient bolster 28, is provided with hydraulic means for varying the position of the end of the bolster 28 relatively to the periphery of the bladed cylinder 5.

The object of this means is to effect the adjustment of the basic thickness, i.e. the space which must exist during processing, between the support bearing 28 and the bladed cylinder 5, as a function of the thickness of the skin to be processed.

These means comprise two hydraulic units connected to the ends of the beam 19 for positioning it relatively to the levers 6 and 7 and comprising the

pistons

22a, 22b and 23a, 23b, the valves 34, 35 with respective slides 34a, 35a controlled by the

units

24, 25, and the cylinders 34b, 35b. Each cylinder 34b, 35b is provided in its centre with an inlet P for pressurised fluid, and two discharge outlets S located at the end.

By rotating the hand wheel 40 in a clockwise direction, it is possible to advance the slides 34a, 35b towards the interior of the machine (direction C, FIG. 4). In this manner the pressure from inlet P is applied to pistons 22a, 23a and pressure on pistons 22b, 23b, is relieved through discharge outlets S causing the advance of the beam 19 in the direction C (closing direction) by the same amount as the slides 34a and 35a are displaced. The advancing beam 19 drives with it the cylinders 34b and 35b of the valves 34 and 35 until the slides 34a and 35a, which are not displaced, close the communicating bores between the

pistons

22a, 22b and 23a, 23b and the cylinders 34b and 35b.

Conversely, by rotating the hand wheel 40 in an anticlock-wise direction, the displacement of the beam 19 is effected in the direction D (opening direction).

During some phases in the processing of a skin, it is advisable to be able to make variations in thickness, i.e., to vary the position of the bolster 28 in a direction which increases the space between its front edge and the bladed cylinder 5 by a set amount.

This is particularly useful at the time of the closing of the machine to prevent the skin being suddenly squeezed between the bolster 28 and the bladed cylinder 5 before the

conveyor rollers

14 and 17 effect a feed, thus avoiding initial contact marks of the blades on the stationary skin. Secondly, it is necessary to increase the space between the bolster 28 and the bladed cylinder 5 when a portion of skin passes between them having a thickness greater than that which is normally compensated by the elasticity of the bolster 28, for example, in the area of the neck or head of the skin, the thickness of which may be two or three times greater than the average thickness of the remaining part of the skin. This considerable increase in local thickness cannot be completely absorbed by the elastic bolster and on previous machines this results in the stopping of the skin with consequent slippage between the conveyor rollers, or the lateral displacement of the skin caused by the thrust of the spiral blades. In each case, the operator is obliged to open the machine and set a new thickness adjustment.

The means provided for such variation in thickness during the processing of a skin consists of a hydraulic unit indicated generally by 33(FIG. 4) which acts on the cylinders 34b, 35b of valves 34, 35 by means of the shafts 36, 37 having at their ends oblique slots 38, 39 which are coupled to valve cylinders 34b, 35b to control the pressure on

pistons

22a, 22b and 23a, 23b for the transverse displacement of the beam 19 carrying the bolster, using the hydraulic system already described for adjusting the basic thickness. For this purpose, the cylinders 34b, 35b of the valves 34, 35 are displaced by the displacement of slots 38, 39 to which the valve cylinders are coupled by yokes affixed to the cylinders and moving in the slots. This unit 33 includes two co-axial hydraulic pistons, the outer one 41 of which has different opposed surfaces and forms the cylindcr of the inner one 42. i

The latter is connected to the shafts 36, 37 provided at the ends with oblique slots 38, 39 acting directly on the cylinders 34b, 35b of the valves 34, 35. The inner piston 42 is actuated through an electrically operated valve (not shown) by pressurised fluid supplied to the inlet P and discharging through the outlet S. The inner piston 42 is normally urged towards the right under the action of the pressure P, but may be moved to the left under the control of the operator at any moment during the operating phase, thus causing a movement to the left (arrow E) of the rods 36, 37 and associated oblique slots 38, 39.

The movements of the inner piston 42 may be limited in the direction of the arrow E by an adjustable mechanical stop 49 and locked on the shaft 37 by the screw 49a.

The outer piston 41 is connected hydraulically in the opening and closing phases of the machine through the openings M and P, as will be subsequently described. The control of the levers 6 and 7 pivoted on the shaft 8, by way of the connecting rod 9 and handle 10, is obtained by rotation of the shaft 44a by the pinion 44 engaging on the rack of the piston 43 and displaceable in the cylinder 45. The cylinder receives pressurised fluid from the lower opening P to effect rising movement of the piston 43 (Arrow A and from the upper opening M for movement thereof downwardly (arrow 8,). Before the end of the downward movement, the piston 43 exposes an outlet m for the pressure fluid so as to control the positioning members for the closure of the machine.

The operation of the machine is as follows:

Firstly, it is necessary to arrange the projecting profile of the bolster 28 by turning polygonal heads 32 to move threaded sleeves 31 until the profile itself is adapted to the variations in thickness of the skin in a transverse direction. The basic thickness is then established by rotating the hand wheel 40 so as to regulate the average space between the projecting edge of the bolster 28 and the bladed cylinder 5 according to the thickness of the skin to be processed.

At this point bolster 28 has been adjusted to the characteristics of the skin being processed, and the machine is ready to execute the opening phase and the closing phase in order then to carry out the actual processing. In order to bring the installation to the machine open phase, pressurised fluid from a suitable hydraulic system (not shown) enters the cylinder 45 from inlet P whereby the piston 43 is urged upwardly (arrow A causing the gear 44 and the associated shaft 44a to rotate in the direction of the arrow A and consequently to pivot cams l0, connecting rods 9 and levers 6, 7 in the direction A A and A removing the roller 12 from the bladed cylinder 5.

The pressurised fluid is also fed to actuate the piston 41, through the opening P in the cylinder 33, whereby the cylinder is urged to the left, taking with it the piston 42 which, in its normal position, is urged to the right by its own independent circuit, urging to the left shafts 36, 37 in the direction of arrow E.

This movement causes the advance of the cylinders 34b, 35b of the valves 34, 35 in the direction of the arrow C, with consequent opening of the passage between inlet P of the pressure fluid and the conduit which leads to the pistons 22b, 23b, to apply pressure fluid to the pistons which, bearing against the levers 6, 7 cause the beam 19 to open (in the direction of the arrow D). This displacement stops when slides 34a, 35a close the communicating bores between

pistons

22a, 22b and 23a, 23b and cylinders 34b, 35b, which are displaced in the direction of the arrow D, since they are connected to the beam 19. The driving roller 12 is in the open position, i.e. at the bottom of the opening movement indicated by arrow A (FIG. 2).

At this point the operator can position the skin on the roller 12 and start the machine in the closing phase. In this phase pressure fluid is fed through port M of the cylinder 45 urging the rack piston 43 downwardly (arrow B,). This movement causes rotation of the pinion 44 and hence of the shaft 44a in the direction pivoting of arrow B, and consequently of the cam 10, connecting rod 9 and lever 7 (similarly on the other side of the lever 6) in the direction of the arrows B B B until the end of the closing movement indicated by arrow B in FIG. 2. At this point the roller 12, with the associated skin, is in contact with rollers l4, 17. The resilient bolster 28 is disposed in front of the bladed cylinder 5 but its spacing therefrom is determined by the adjustment of the basic thickness with an increment due to the feature that piston 41 is again displaced to the left (arrow E), with the consequence that, as stated, the beam 19 is displaced in an opening direction (arrow D).

At the moment piston 43 completes its downward movement (arrow 8,), it uncovers the opening M of cylinder 45 and the pressurized fluid, coming from M, is fed to (a) hydraulic units 18 (FIGS. 1 and 2) which, by means of levers l3 and 16, urge rollers l4, 17 against roller 12; (b) to a hydraulic motor (not shown) which, by way of transmissions 46, 47, 48 (FIG. 4) rotates

rollers

12, 14, 17,. starting the feed of the skins; and (c) to opening M of cylinder 33, pressing on differential piston 41 which, having a surface greater than that which is turned towards opening P at the side of opening M, is urged to the right (arrow F), followed by the piston 42 which is constantly fed from inlet P. In this manner, rods 36, 37 and oblique slots 38, 39 are displaced to the right (arrow F). This movement causes the advance of cylinders 34b35b in the direction of arrow D, with the consequence that the beam 19 is displaced in the direction of arrow C, until reestablishment of the hydraulic balance is obtained by the closing of the openings by the slides 34a, 35a.

Consequently, with the closing of the machine, the beam 19 is in a more retracted position relatively to that established by the adjustment of the basic thickness. Only after the

rollers

12, 14, 17 have been started and hence the skin advanced and at the end of the travel of the pistons 41 and 42 is the distance between the outer edge of the bolster 28 and the bladed cylinder 5 predetermined by operating the hand wheel 40. In this manner, a pressure mark of the blades on the skin is avoided.

During the processing, the bladed cylinder 5 cuts the flesh from the inside of the skin while the skin is carried upwardly. Any elevations or cavities existing in the skin surface are absorbed by the resilient bearing 28.

When the operator considers it advisable, he can feed pressurised fluid through port S to the piston 42 by means of a valve, displacing it from the right, where it had been, to the left in the direction of the arrow E, with consequent movement of the rods 36, 37 and withdrawal of the beam 19, thus increasing the space between the bearing 28 and the bladed cylinder 5.

The amount of this increase may be set by suitably positioning the stop 49 on the rod 37.

When processing is concluded, the operator reverses the flow of fluid, causing it to reach the cylinder 45 via opening B in order to urge the piston 43 upwardly and terminate the already described opening operations.

I claim: I. A device in a skin working machine for the resilient support of a skin having an average thickness and variations in the thickness, which machine comprises a framework, a skin working cylinder mounted on the framework, a beam mounted on the framework for displacement relative to the skin working cylinder and plane guide means on the beam, and the resilient support including a resilient bolster mounted on the plane guide means for reciprocation in the plane guide means towards and away from the working cylinder, the bolster having a substantially parallelopiped shape and defining longitudinal grooves extending in the direction of the beam and a plurality of transverse bores substantially perpendicular to the grooves near an end of the bolster remote from the skin working cylinder, an opposite end of the bolster adjacent the skin working cylinder forming a nip therewith for receiving the skin, a plurality of adjusting units spaced regularly along the entire length of the bolster in said direction and arranged to adjust the spacing of the opposite bolster end from the working cylinder in accordance with the average thickness of the skin being worked, and hydraulic means for displacing the beam relative to the working cylinder whereby the nip is set to a basic thickness corresponding to the average thickness of the skin being worked, and for further displacing the beam whereby the nip is set to an operating thickness corresponding to variations in the average skin thickness.

2. A device in a skin working machine as defined in claim 1, wherein the transverse bores are irregularly spaced along the bolster in said direction, the bores having different diameters and shapes.

3. A device in a skin working machine as defined in claim 1, wherein the transverse bores are grouped, groups of the bores being aligned with respective ones of the adjusting units.

4. A device in a skin working machine as defined in claim 1, further comprising plugs of elastic material inserted in at least some of the transverse bores.

5. A device in a skin working machine for the resilient support of a skin having an average thickness and variations in the thickness, which machine comprises a framework, a skin working cylinder mounted on the framework, a beam mounted on the framework for displacement relative to the skin working cylinder and plane guide means on the beam, and the resilient support including a resilient bolster mounted on the plane guide means for reciprocation in the plane guide means towards and away from the working cylinder, the bolster having an end remote from the working cylinder, and an opposite end forming a nip therewith for receiving the skin, a plurality of adjusting units spaced regularly along the entire length of the bolster in the direction of the beam and arranged to adjust the spacing of the opposite bolster end from the working cylinder in accordance with the average thickness of the skin being worked, and hydraulic means for displacing the beam relative to the working cylinder whereby the nip is set to a basic thickness corresponding to the average thickness of the skin being worked, andfor further displacing the beam whereby the nip is set to an operating thickness corresponding to variations in the average skin thickness, the hydraulic units having oppositely disposed pistons for displacing the beam, and displaceable slide valves controlling the pistons of the hydraulic units, a first slide valve being manually controllable for moving a respective one of thehydraulic units for setting the nip to the basic thickness, and a second slide valve being automatically controlled in response to variations in the skin thickness for setting the nip to the operating thickness.

6. A device in a skin working machine as defined in claim 5, further comprising a pair of pivotal levers sup-,

porting the beam ends displaceably relative to the skin working cylinder, the hydraulic units each comprising a cylinder housing respective one of the pistons, the pistons being connected to the levers for movement therewith, and the cylinders being connected to the beam and being controlled for movement by the second slide valves.

7. A device in a skin working machine as defined in claim 6, wherein the second slide valve comprises two coaxial hydraulic pistons, an external one of the two pistons forming a cylinder for the internal piston, and further comprising mechanical means controlled and operated by the internal piston, the mechanical means being arranged to control and move the cylinders of the hydraulic units.

8. A device in a skin working machine for the resilient support of a skin having an average thickness and variations in the thickness, which machine comprises a framework, a skin working cylinder mounted on the framework, a beam extending in a longitudinal direction, a pair of pivotal levers supporting the beam ends on the framework for displacement of the beam relatively to the skin working cylinder for moving the beam between an open and a closed position in relation to the working cylinder, the beam ends being horizontally displaceably mounted on the levers, plane guide means on the beam, and the resilient support including a resilient bolster mounted on the plane guide means for reciprocation in the plane guide means towards and away from the skin working cylinder, the bolster having an end remote from the working cylinder and an opposite end forming a nip therewith for receiving the skin, a plurality of adjusting units spaced regularly along the entire length of the bolster in said direction and arranged to adjust the spacing of the opposite bolster end from the working cylinder in accordance with the average thickness of the skin being worked, each beam end defining a pair of oppositely directed hydraulic cylinders extending transversely to said direction, a pair of pistons connected to each lever and extending into a respective ones of the cylinders, a first slide valve including a cylinder part and a piston part slidable in respect of each other for controlling flow of hydraulic fluid into the cylinders of each beam end, one of the slide valve parts being manually controllable for horizontally displacing the beam relative to the working cylinder whereby the nip is set to a basic thickness corresponding to the average thickness of the skin being worked, and a second slide valve automatically controlled in response to variations in the skin thickness when the beam is in the closed position and operating the other slide valve part for further displacing the beam relative to the working cylinder whereby the nip is set to an operating thickness corresponding to variations in the average skin thickness.

9. A device in a skin working machine for the resilient support of a skin as defined in claim 8, wherein the second slide valve comprises two coaxailly hydraulic pistons, an external one of the two pistons of the second slide valve forming a cylinder for the internal piston thereof, and further comprising mechanical means controlled and operated by the internal piston, the mechanical means being arranged to move the other slide valve part of the first slide valve.

Claims

1. A device in a skin working machine for the resilient support of a skin having an average thickness and variations in the thickness, which machine comprises a framework, a skin working cylinder mounted on the framework, a beam mounted on the framework for displacement relative to the skin working cylinder and plane guide means on the beam, and the resilient support including a resilient bolster mounted on the plane guide means for reciprocation in the plane guide means towards and away from the working cylinder, the bolster having a substantially parallelopiped shape and defining longitudinal grooves extending in the direction of the beam and a plurality of transverse bores substantially perpendicular to the grooves near an end of the bolster remote from the skin working cylinder, an opposite end of the bolster adjacent the skin working cylinder forming a nip therewith for receiving the skin, a plurality of adjusting units spaced regularly along the entire length of the bolster in said direction and arranged to adjust the spacing of the opposite bolster end from the working cylinder in accordance with the average thickness of the skin being worked, and hydraulic means for displacing the beam relative to the working cylinder whereby the nip is set to a basic thickness corresponding to the average thickness of the skin being worked, and for further displacing the beam whereby the nip is set to an operating thickness corresponding to variations in the average skin thickness.

5. A device in a skin working machine for the resilient support of a skin having an average thickness and variations in the thickness, which machine comprises a framework, a skin working cylinder mounted on the framework, a beam mounted on the framework for displacement relative to the skin working cylinder and plane guide means on the beam, and the resilient support including a resilient bolster mounted on the plane guide means for reciprocation in the plane guide means towards and away from the working cylinder, the bolster having an end remote from the working cylinder, and an opposite end forming a nip therewith for receiving the skin, a plurality of adjusting units spaced regularly along the entire length of the bolster in the direction of the beam and arranged to adjust the spacing of the opposite bolster end from the working cylinder in accordance with the average thickness of the skin being worked, and hydraulic means for displacing the beam relative to the working cylinder whereby the nip is set to a basic thickness corresponding to the average thickness of the skin being worked, and for further displacing the beam whereby the nip is set to an operating thickness corresponding to variations in the average skin thickness, the hydraulic units having oppositely disposed pistons for displacing the beam, and displaceable slide valves controlling the pistons of the hydraulic units, a first slide valve being manually controllable for moving a respective one of the hydraulic units for setting the nip to the basic thickness, and a second slide valve being automatically controlled in response to variations in the skin thickness for setting the nip to the operating thickness.

6. A device in a skin working machine as defined in claim 5, further comprising a pair of pivotal levers supporting the beam ends displaceably relative to the skin working cylinder, the hydraulic units each comprising a cylinder housing respective one of the pistons, the pistons being connected to the levers for movement therewith, and the cylinders being connected to the beam and being controlled for movement by the second slide valves.