GB2189297A

GB2189297A - Friction clutch for punching-machine

Info

Publication number: GB2189297A
Application number: GB08706838A
Authority: GB
Inventors: August Thomas Portmann
Original assignee: Bruderer AG
Current assignee: Bruderer AG
Priority date: 1986-04-18
Filing date: 1987-03-23
Publication date: 1987-10-21
Also published as: DE3707392A1; FR2597566A1; IT8747778A0; JPS63214522A; GB8706838D0; IT1205765B

Abstract

In a friction clutch for a punching-machine, a driven flywheel (1), Fig. 1, is supported rotatably on a main shaft (3) and a clutch disc (4) is mounted for rotation with the main shaft (3), frictional engagement between clutch disc (4) and flywheel (1) proceeding as a result of axial motion of a pressing plate (9) against the clutch disc (4). This motion is produced by pressurised fluid acting upon pistons (12). The pressing plate (9) is connected to the flywheel (1) by means of generally tangential leaf springs (19), Fig. 4, which are each secured to a pressing plate lug (17) at the centre of the spring and to flywheel (1) at the spring ends, to allow axial shifting of the pressing plate (9). The springs (19) hold the pressing plate (9) centered within the flywheel (1). <IMAGE>

Description

SPECIFICATION A coupling means between the flywheel and the pressing plate of a punching machine having a single-disc clutch This invention relates to a coupling meansfora punching machine having afluid operated single-disc clutch, which coupling means is arranged between the driven flywheel and the pressing plate of the punching machine and which single-disc clutch is operative drivingly to couple the flywheel to the main shaft ofthe punching machine.

The clutch includes a flexible, axially resiliently yielding clutch disc which is caused frictionally to engage the flywheel by a fluid pressure generated axial shifting movement of the pressing plate.

The drive of punching machines of the above mentioned kind proceeds, for instance, by means of a belt drive acting upon the flywheel of the punching machine which is mounted for free rotation on the main shaftofthe machine. An inner space in the shape of a hollowcylinderisformed intheflywheel and the clutch disc is located in that space, this clutch disc being mounted for rotation with the main shaft of the machine. This clutch disc forms part of a single-dise clutch ofthe punching machine and is movable into frictional engagement with the flywheel so as to coupletheflywheel to the main shaft of the machine in a force locked manner.The deflecting of the clutch disc necessary to accomplish this task and to overcome the travel between engagement and disengagement is achieved by a fluid pressure operated pressing plate acting upon the clutch disc.

One friction surface of such single disc clutches is located at the flywheel. The second friction surface is pressed by the above-mentioned pressing plate onto the clutch disc provided in turn with friction linings whentheflywheel is coupled in a force locked mannerto the machine's main shaft by means of the single-disc clutch. The pressing plate is also located within the inner space of the flywheel having the shape of a hollow cylinder and located axially adjacent the clutch disc and can be shifted within the flywheel in an axial direction.If the axial shifting of the pressing plate against the clutch disc is generated by pressurised air, the pressing disc is designed with an annular piston which projects into an annular space provided in the flywheel and acting as cylinder chamber. If the axial shifting ofthe pressing plate against the clutch disc is achieved by a hydraulic fluid under high pressure, a plurality of pistons is provided acting between the pressing plate a nd the flywheel, wh ich pistons are inserted in cylinder chambers formed within the flywheel.

The pressing plate must be arranged in the flywheel in an axially shiftable manner and must be, moreover, arranged so that it positively rotates therewith. To this end generally known punching machines include a pressing plate which is attached to the flywheel by the agency of splined shafts, gear-toothed systems, or a plurality of bolts. Quite obviously, the pressing plate must in all circumstances be axially movable within the flywheel and accordingly the above mentioned fixtures must incorporate some play, albeit a small amount only.

Generally known arefurthercouplingsinwhich the pressing plate is mounted upontheflywheel by means of spring members without free play but in an axially resilient manner.

In punching machines which generate extremely large positive and negative moments due to the moved masses (plunger, upper part of the tool and balancing weight), which moments amountto more than 50% of the moment of the coupling, the pressure plate will be moved backandforth in a circumferential direction twice per one complete rotation along a distance corresponding to the play of the various members of the fixtures (e.g. play between a peg and the bore in which such peg is received), which oscillating movement favours knocking out of these fixtures.

Hence, it is an object to provide a coupling means comprising at least two leaf spring members attached rigidly and free of play to the pressing disc and flywheel, respectively. These leaf spring members extend tangentially around the diameterof the coupling means and form atorsionallystiff connection between the pressing plate and the flywheel and hold the pressing plate rigid relativeto the flywheel in the radial direction and accordingly keep the pressing plate centered but allow an axial movement of the pressing plate relative to the flywheel, which leaf spring members are attached at both their ends to the flywheel and their respective centre areas to the pressing plate.

Because of that design the leaf springs can be located at a large radius and accordingly relatively small forces oftransmission exist in the circumferential direction of the coupling means.

Furthermore, all leaf springs are subjected to only one-half ofthe tensile stress in both senses of rotation of the moment. Furthermore,the arrangement on a large radius allows the use of long leaf springs without the necessity for increasing the diameter of the flywheel. In spite of this, there is enough space to allow the placing of the return springs. Finally leaf springs can be produced rather easily and without waste material.

The present invention should be more fully understood by reference to the following detailed description in conjunction with the accompanying drawings, and wherein: Figure lisa section along line I-I of Figure 4 and of an embodiment operated by high pressure hydraulic fluid; Figure 2 is a section similarto that of Figure 1 but of an embodiment operated by pressurised air; Figure2a is a section along line ll-ll of Figure 4; Figure 3 is a section along line Ill-Ill of Figure 4; and Figure 4 is a plan view of an embodiment ofthe inventive coupling means.

Aflywheel 1 which is made of a plurality of parts is supported by frictionless bearings 2 freely rotatable on the main shaft 3 ofthe high speed punching machine. The flywheel 1 is driven by a not specifically illustrated drive according to known designs. There may be, for instance, a belt drive, in which case one part of the flywheel is formed as a belt pulley. The rotation speed of the flywheel 1 may for example be 1000 rpm. An axially resilient deflectable clutch disc4 is mounted by means of coupling elements, e.g. in the form ofthreaded bolts 5 rigidly to the main shaft 3 to rotate therewith. The clutch disc 4 carries on both sides friction iinings 6,7 distributed along its circumference.In the clutched condition the friction linings 6frictionally engage the friction surface 8 arranged on the flywheel 1. A pressing plate 9 is located at the side of the clutch disc 4 opposite the flywheel 1. This pressing plate 9 has a friction surface 10 intended to co-operatewith the friction linings 7 of the clutch disc 4.

The pressing plate 9 is arranged to be axially shiftable within the flywheel 1. The shifting movement of the pressing plate 9 against the clutch disc 4 orflywheel 1, respectively, is produced for instance hydraulically or pneumatically.

Figure 1 illustrates an example of an hydraulically operating embodiment. To this end a plurality of cylinder chambers 11 are arranged within the flywheel 1 and distributed along a circular line with hydraulic pistons 12 inserted in the cylinder chambers 11. The piston seals are identified by reference numeral 13. The hydraulic pistons 12 act directly upon the pressing plate 9.If a pressurised hydraulic fluid is led through the channels 23 into the cylindrical chambers 11 and accordingly act upon the hydraulic pistons 12, the pressing plate 9 is urged againsttheclutch disc4(i.e. inthedrawingfigureto the left), which clutch disc4 in turn gets pressed againsttheflywheel 1 and accordingly produces through the friction surface 8 of the flywheel 1 and the friction lining 6 of the clutch disc 4 a force locked connection or coupling, respectively, between the flywheel 1 and the main shaft3 such thatthe punching machine is in its operative condition.

Figure 2 illustrates an exemplary embodiment of a pneumatic design. The main parts of Figure 2 which arethesame as those of Figure 1 have the same reference numerals. The flywheel 1 comprises an annularcylindricalchamber14extending,for instance, concentrically relative to its circumference.

The pressing plate 9 includes an annular piston 15, whereby this annular piston can also be designed as separated from the pressing plate 9, which annular piston 15 is located within the cylinder chamber 14.

The piston has seals 16. Corresponding to the operation which has been described with reference to Figure 1 the axial shifting movementofthe pressing plate 9 against the clutch disc 4 is achieved in that pressurised air is ied through channels 23 into the cylinder chamber 14 and accordingly the pressing plate 9 is urged against the clutch disc4.

Reference is now made to Figure 4 and Figure 3, which latter illustrates a section along line Ill-Ill of Figure 4. The pressing plate 9 is designed with lugs 17 projecting therefrom in a radial direction. These lugs 17 are rigidly coupled, for instance, by means of threaded bolts 18, to the centre area of a leaf spring 19. The end sections 20,21 of the respective leaf springs 19are rigidly mounted bymeansoffurther threaded bolts 1 8to the flywheel 1. Accordingly, a torsionally stiff coupling between the pressing plate 9 and the flywheel 1 is achieved, so that these two members cannot be rotated relative to each other.

Furthermore, the fourleafsprings 19 hold the pressing plate 9 centered relative to the flywheel 1, because when viewed in a radial direction ofthese two members a rigid connection also exists.

However, by means of high pressure hydraulic fluid introduced into the cylinder chamber 11 or pressurised air introduced into the cylinder chamber 14, the pressing plate9can be moved againstthe spring force of the four leaf springs 19 which now bend somewhat, in the axial direction oftheflywheel 1 against the clutch disc 4 so as to produce the frictional engagement between the driven flywheel 1 and the clutch disc 4, which is mounted for rotation with the main shaft 3.

Because the travel between engagement and disengagement of the above described single disc clutch and accordingly, the axial distance of movement of the pressing plate 9 is obviously extremely small and accordingly the extent ofthe spring elastic bending of the leaf springs 19 is extremely small, the return movement of the leaf springs 19 is supported by return springs 22 and 22', respectively. These return springs 22,22' are spiral springs 22,22' located in an annular base 24 of the flywheel 1. Becausethis annularspace 24 must be at any rate presentforthe arrangement of the leaf springs 19, a space saving solution regardingthe locating of the return springs 22 is arrived at.The specific location of these return springs 22,22' illustrated in Figure 4 isto be considered as an example only. Embodiments including more or less than the number of the illustrated return springs are possible.

If the leaf springs 19 are bent due to the axial movement of the pressing plate 9 towards the clutch disc 4, the return springs are tensioned, and they are pressed together. As soon as the hydraulic or pneumatic respectively, pressure drop occurs, these leafsprings 19 strive to return into their rest position and to move the pressing plate 9 in a direction leading awayfrom the clutch disc4andthisshifting movement is supported by the return springs 22,22' such that an extremely speedy disengagement ofthe frictional engagement between flywheel 1 and clutch disc 4 is attained.

The illustrated embodiment of resilient spring members coupling the pressing plate 9 to the flywheel 1 is shown embodied in four leaf springs 19.

It is, however, also possible to provide leaf spring piles in place of one single leaf spring 19.Afurther embodiment foresees, for instance, two leaf springs located diametrically opposite each other.

While there are shown and described present preferred embodiments ofthe invention, it isto be distinctly understood that the invention is not limited thereto, but may be otherwisevariouslyembodied and practised within the scope of the following

Claims

claims. CLAIMS

1. Acoupling meansfora punching machine having a fluid operated single-dise clutch, which coupling means is arranged between the driven flywheel and the pressing plate of said punching machine and which sing le-dise clutch is operative drivinglyto couplesaidflywheel to the main shaft of the punching machine and includes a flexible, axially resiliently yielding clutch disc which is caused to frictionally engage said flywheel by a fluid pressure generated axial shifting movement of said pressing plate.

said coupling means comprising at least two leaf spring members mounted rigidly and free of play on siad pressing plate and flywheel, respectively,which leaf spring members extend tangentially around the diameter of the coupling meansandform a torsionally stiff connection between said pressing plate and said flywheel and hold said pressing plate rigidly relative to said flywheel in the radial direction and accordingly keep said pressing plate centered but allow an axial movement of said pressing plate relative to said flywheel, which leaf spring members are mounted at both their ends to said flywheel and at their respective centre areas to said pressing plate.

2. The coupling means of cia im 1, wherein each leaf spring member comprises a plurality of individual leafsprings.

3. The coupling means of claim 1, in which four leaf spring members each intheform of one leaf spring are present, each leaf spring being mounted rigidly to said flywheel and pressing plate, respectively.

4. The coupling meansofclaim 1,including return springs located in an annular recess in said flywheel extending coaxiallyto the axis of rotation of said flywheel, which return springs resiliently exert pressure onto said pressing plate to bias said pressing plate away from said flywheel so asto support the return movement of said leaf spring members.

5. Acoupling means,fora punching machine having a fluid-operated clutch, substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.