AU627713B2 - A method for joining two or several overlaying sheet formed members together, metal or non-metal, and an apparatus for carrying out the method - Google Patents

Description

F r~ OPI DATE 25/08/89 wo' AO0P DATE 28/09/89 APPLN. ID 30551 89

PCT

PCT NUMBER PCT/SE89/00037 INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (51) International Patent Classification 4 (11) International Publication Number: WO 89/ 07020 B21) 39/00 Al (43) International Publication Date: 10 August 1989 (10.08.89) (21) International Application Number: PCT/SE89/00037 (74) Agent: BAUMBACH, Thorkild; Ankarvagen 4, S-761 Norrtalje (SE).

(22) International Filing Date: 2 February 1989 (02.02.89) (81) Designated States: AT (European patent), AU, BE (Eu- (31) Priority Application Number: 8800407-2 ropean patent), BR, CH (European patent), DE (European patent), DK, FI, FR (European patent), GB (32) Priority Date: 5 February 1988 (05.02,88) (European patent), IT (European patent), JP, KR, LU (European patent), NL (European patent), NO, SE (33) Priority Country: SE (Eurnnean nntnt IM (71) SECTION 34(4)(a) DIRECTION SEE FOLIO 0- 1 NAME DIRECTED A\-f2Q E N T Inveniors/Applicants uur uo only UUDDUI O Luciano [IT/CH]; Tir-Fed6ral 16, CH-1024 Ecublens RAPILLARD, Philippe [CH/CH]; Chemin de Grange-Canal 6, CH-1208 Geneva (CH).

627713 (54)Title: A METHOD FOR JOINING TWO OR SEVERAL OVERLAYING SHEET FORMED MEMBERS TO- GETHER, METALOR NON-METAL, AND AN APPARATUS FOR CARRYING OUTTHE METHOD (57) Abstract A method for joining together two or several overlaying sheet formed members (10, 11), metal or non-metal, at which a coaxial arrangement of a punch a die and an anvil cooperate by means of thelt relative movement.

The punch (12) carries out a first movement coax(aliy towards said die Thereafter the anvil moves in the opposite direction. The anvil is axially blocked and sai' punch (12) carries out a second movement coaxially towards said anvil to a position between the anvil and the punch (12) which is dependent on the applied forces, the thickness, the number and the material of the sheet-formed members (10, 11).

WO 89/07020 PCT/SE89/00037 A METHOD FOR JOINING TWO OR SEVERAL OVERLAYING SHEET FORMED MEMBERS TOGETHER, METAL OR NON-METAL, AND AN APPARATUS FOR CARRYING OUT THE METHOD.

TECHNICAL FIELD This invention relates to methods for joining two or several overlaying sheet formed members together, metal or non metal, and apparatuses for carring out such methods.

BACKGROUND ART It is well known that a pair of overlaying metal members could be. joined together by lancing and forming a part of one member through an unblanked part of the other member.

and thereafter staking the lanced and formed part of the one member to an adjacent surface of the other member to secure the members together in overlaying relation.

For example the US-A-3 924 378 shows such a joining operation carried out by means of an apparatus having two separately actuatable rams, one of the rams carrying a lancing and forming die, and the other ram carrying a flattening punch or anvil whereby the one ram performs the lancing and forming operation and the other ram performs the staking operation. The apparatus is provided with adjustment means so that the upper sheet or sheets of the displaced section is not engaged by the downwardly moving flattening punch until the lowermost sheet of the di,placed section is uncovered by the upwardly moving die so as to allow; the lower sheet of the displaced section to be spread SUB8TITUTE SE ET WO 89107620 PCT/SE89/00037, 2 while the upper sheet or sheets are still confined by the die. Thus, said adjustment means must be operated for different thickness of the sheets.

US-A-4 035 901 shows an apparatus having a single reciprocating head provided with a first means, a die, to perform the lancing and forming step on a first stroke of the head and provided with a second means, '41-e. Ian anvil, that performs the staking operation on the second stroke Gf the same head. When the thickness of one or several of the sheets to be joined together or the material 4 of the sheets is changed the stroke length of tile first and the second strokes must be adjusted.

GB-A-i 603 231 shows another machine for making a joint of the abovementioned type. In this machine the moving head comprises the punch which in a first stroke pierces the I] sheets against the die placed underneath said sheets.

Before the second stroke the die as well as the anvil are axially repositioned by means of holding means having inclined plane surfaces. If the thickness of the sheets is changed the reposition movement must be adjusted.

The above examples of prior art all disclose systems having a relatively simple one-piece, non-expansible die. The corresponding machines are in principle of tho two-stroke cye The second stroke is carried out with the deformed sections of the sheets at least partly outside the die.

However, other systems and apparatuses operating with only one stroke are known in which the die is laterally expansible. in this type of apparatuses the second part of the joint-forming-process takes place inside the die.

US-A-4 459 735 discloses an apparatus and a method of this type. By necessity the design of the die is much hiore complicated in a system like this and the choice o buuts lITUTE 8I{AET4 'I W08! 9/07020 PCT/SE89/00037 material for the die might be critical. Thus the life expectation for such a die is comparatively l w which makes the maintenancey costs high for the tool. 1n addition one and the same die cannot be used if the thickness of the sheets is changed.

DISCLOSURE OF THE INVENTION One object of the present invention is to provide a method for joining together two or several overlaying sheet-formed members in a two-stroke process which method can produce a first type of joint with a single set of die, punch and anvi]. and without adjustment of said units for different sheet thickness, number or material.

Another object of the invention is to provide an apparatus for carrying out said method, capable of producing at least two different types of joints, e.g. leak proof and non-leak proof joints, using different sets of die, punch and anvil.

Piue to the fact that the the joint according to comparatively low it is apparatus to be very light versatile hand-held tool.

mechanical forces needed to the inventive method also possible to design and compact for the use make are the as a jilt A further advantage of the invention is that the life oxpectations for the tool units punch, die and anvil, especially the critical die, are high. This is due to the 30 relatively rugged design of the die compared to known designs.

Our invention which provides a solution to the said technical problems is characterlsed according to the appended claims.

SUBSTITUTE

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i r c r i PRls~?rr WO 89/07020 PCT/SE89/00037 4 BRIEF DESCRIPTION OF THE FIGURES Other objects, uses and advantages of this invention are apparent from the reading of this description which proceeds with reference to the accompanying drawings forming part thereof and wherein: Figure 1 shows an apparatus according to the present invention implemented as a hand held tool.

Figure 2a is a diagram showing on a time scale the motion of three essential parts of the machine.

Figure 2b is a signal diagram showing the input and output signals to and from the apparatus according to figure 1 as well as certain internal signals of the connected control unit.

Figure 3 shows the essential phases of a complete operation cycle.

Figure 4 shows a second embodiment of the control unit.

Figure 5 shows a third embodiment of the control unit.

Figure 6 shows a fourth embodiment of the control unit.

Figure 7 shows an alternative arrangement of the punch, die and anvil according to the invention.

Figure 8 shows a type of joint which could be produced by means of the arrangement according to figure 7.

SUBSTITUTE SHEET 1I WO 89/07020 C/E900- Figure 9 shows examples of sectioizs through joints according to figure 8.

Figure 10 shows a section tircugh a circular joint which could be produced with an arrangement according to figure 1.

DETAILED DESCRIPTION OF THE INVENTION Figure 1 shows an apparatus according to the present invention. The embodiment refers to a handheld tool, but the principles of the method and the apparatus are applicable to stationary equipment as well.

The main parts of the machine are the body 1 with the handle 20. The body is provided with, three moving systems.

The first of those systems constitute a single-acting cylinder-piston assembly with a piston X in the cylinder 2 and a spring 13. The piston is mechanically coupled to a punch 12 which is moved by the piston. The second moving system comprises a' movable anvil Y, a spring guiding member 4 and a spring 5. The member 4 transfers the forces from said spring 5 to the anvil Y. All said parts are contained in the cavity 3. The anvil Y is coaxially movable with the punch 12. In one direction, i.e to the right in figure 1, the anvil is moved by means of forces from the spring transfered through the member 4 and in the other direction it is moved by means of forces from the punch 1Z.. in this 0Particular embodiment the anvil Y is guided by a die 9 which cooperates with the punch 12. The third moving system is also a single-acting cylinder-piston combination 6i8,7,21. The piston 6 is mechanically coupled to the blocking member z which acts on the anvil Y.

In order to operate the three different moving systems hydraulic and/or pnevii)atic pressure signals are connected SUBSTITUTE 8GRET

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WO 89/07020 PCT/SE89/00037, 6 to the systems by means of conduits or channels 15,16,17 within the body 1. A handle 20, scematically shown in figure 1, is fixed to the body 1. The handle is provided with a manual valve 19 which in this case is a three way/ two position/ normally closed. valve having a trigger 18.

The fluid input/output ports of the tool are marked G, A, H, C, P and %he corresponding fluid signals are designated g, a, h, c, p.

For the operation of the tool the input/output ports have to be connected to a control kinit which could be designed in many different ways. The control unit provides a sequence of signals to the different ports during the operation cycle.

Figure 2b shows a signal diagram for the input/output signals at the respective ports during one complete operation cycle and figure 2a the resulting movements of the three moving systems of the tool. In this part of the description only signals g, a, h, c, p are considered. The other signals illustated in figure 2b are internal signals of the control unit which will be described later on. The signals now considered have all been illustrated as binary signals in which the transfer between tihe two signal levels takes place without any time delay. In reality this is of course not the case but for the sake of simplicity the hydraulic/pneumatic signal time delay is not considered here. On the other hand the time delays in the physical movements of the three systems are much larger and have to be taken into account. These time delays are therefore shown in figure 2a. Although the movement between different positions of the systems are not linear in time, they have for the sake of simplicity been so illustrated in figure 2a, SUBSTITUTE SHEET WO 89/07020 PCT/SE89/00037 7 As mentioned above a certain sequence of signals must be provided at the input/output ports to make the tool work.

Many different embodiments of control units capable of delivering such a sequence could be envisaged a few examples of which will be described below.

At first a general description of the operation of the tool will follow without any reference to details of a specific control unit.

Consider figures 1 and 2. Up to time tO the tool is in its rest position having its control unit connected to the power source, i.e. in this case pneumatic pressure, ready to operate. The input port P is during the whole cycle provided with pneumatic pressure which could be seen from figure 2b. In the following it is assumed that two sheets 10,11 which are to be joined together are positioned between the punch 12 and the die 9.

At time tO the trigger 18 is operated which causes the pressure from input P to be connected through the valve 19 to output A. As a response to this pressure raise at output A the control unit deliveres a high pressure hydraulic hignal g to input port G and the first moving system. As mentioned above the minor time delays between the occurence of these signals are not considered here. The oil which now enteres the cylinder 2 ok the first moving system causes the piston X to start its mIovement to the left in figure 1.

The punch 12, moving with the piston X, will reach contact with the sheet 11 at time ti. When making a first type of joint, the punch 12 at the corresponding position will start to cut the two sheets and the anvil Y of the second moving system will be moved to the left in figure 1 against the force of the spring 5. This movement continues unti] the piston X reaches the position cl at time t2 illustrated in figure 1 and 2. At this position the punch has just cut AUBSTITUTS SH Ct WO 89/07020 PCT/SE89/00037, 8 through the two sheets 11 and 10 along part of the punch circumference. The length of the piston stroke is defined by the design of the first moving system. With an appropriate length of the punch 12 the corresponding position of the punch tip could, e.g.,be made flush with the common surface between the sheet 10 and the die 9. As can be seen from figure 2a the *anvil has now reached tht! position c2.

In the next step, at time t3, the control uniL deliveres a signal c on the input C with a set time delay tl measured from the operation of the trigger. In the present embodiment this signal is a pneumatic signal. Thq signal acts on the third moving system of the tool and actuates the piston 6 which forces the blocking member Z against the anlvil Y without engaging the blocking slot 22. At the same time the hydraulic pressure to the first moving system drops as can be seen from figure 2b. This means that the piston X of the first moving system will start moving to the right in the figure I forced by the two springs 13,5.

The anvil Y and the two sheets 10,11, still in contact with the punch 12, will follow the moveoent to the right in figure 1.

The third moving system is still under pressure and at time t4 the blocking slot 22 is just opposite to the blocking member Z. Thus, the anvil will be blocked in the corresponding position when the piston 6 moves forward,. Tile third moving system could consequently also be consideVted as a position indicator for the anvil. When moving forward tile piston 6 opens a conduit or channel for tie pressure signal h Which is an output signal from the tool to the control unit indicating that the anvil has reached A defined position and is now blocked. The control %init responds by once again delivering hydraulic pressure on input G of the tool. The direction of the movement of tho SUBSTITUTE 8.M" 1, WO 89/07020 WO 8907020PCT/SE89/00037 '1 first moving system is reversed and the punch 12 carries out a second stroke. As mentioned above the anvil is now blocked in position c3, cf., figure 2a.

The deformed portions of the two sheets 10 and 11 are now outside or at least partly outside the die 9. Mechanical forces between the punch 12 and the anvil Y will noQw squeeze the deformed portions of the two sheets and make these portions expand laterally. As long as the operator holds the trigger nothing more will happen in the tool after the punch 12 has reached its final positi n which is dependent on the pressure of the signal g and the thickness and material of the sheets to be joined. The pressure will be set manual~ly on the control unit to an appropria1te value as described below.

At time t5, in this particular embodiment defined as the moment when the trigger is released, all the signals r:xcept p return to zero and the tool returns to its rest posiition.

The time interval between to and t5 is defined as t2 in figure 2. This time interval could of course alternatively be set internally in the control unit. At time t5, thus, the piston of the first moving system will once again reverse its direction of movement. At the same time the blocking member Z will release the anvil, As can be seen from figure 1 the blocking member is still blocking the spring guiding member 4 so that the anvil cannot move further to the right. Due to the mechanical deformations of the s6heets around the punch they will follow the punch in its movement to the right until they reach the edge of the cylinder housing in the tool gap. At this point they will be disengaged from the punch 12 which continues its motion to the right to the rest position. In the diagram 2b this moment corresponds to time t6, Ja1RerIUTE S~IA~.Er i-A WO 89/07020 PCT/SE89/00037.

Figure 3(I-V) shows the essential phases of a complete operation cycle. The tool as illustrated is the same as just described and the connected control unit is an exemple of such a unit capable of delivering the signals of figure 2b. The designations of the five figures(I-V) correspond to the same designations in figure 2.

Figure 3(I) shows the status of the control unit when the input 38 is provided with pneumatic pressure from a standard source available in the workshop. The unit 27 is a standard air preparation unit including a filter, a regulator and a lubricator. This part of the control unit is not essential for the description of the operation of the circuit. It forms, however, part of a practical realisation of said circuit. As can be seen the input P of the tool is provided with the regulated pressure already at this stage. The inputs to the valves 29,28,25, all of the 3 way/2 position, normally closed, pressure controlled type, are also provided with regulated pressure. At the input of the valve 25 a second regulator 26 is arranged to set the pressure to the pneumatic-hydraulic booster 24 and thus the output hydraulic pressure to the input G of the tool which in its turn operates the first moving system of the tcol, This state corresponds to the time before tO in figure 2.

As described above at time to the trigger was operated which caused an operating signal a to be transfered to the control unit, cf., figure 3 When this signal is received by the control unit the following will happen. The valve 25 will open and the regulated pressure from its input will be communicated to the input of the booster 24.

The signal a will also be conducted through the valve Which is of the 3 way/2 position, normally open, pressure controlled type, to the pneumatic OR-gate 33 and open the hydraulic, 3 way/2 position, normally closed valve 37. As a result tle amplified hydraulic pressure at tle output side

SHEET

WO 89/07020 PCT/SE89/00037 11 of the booster 24 will be conducted through said valve to the input G of the tool. At the same time the pneumatic delay circuit 31,32 will be activated which starts the time delay tl, cf., figure 2.

Assuming that the trigger is still operated the next change in thc signal state at the output of the control unit will be decided by the time delay tl. The output signal b from the delay circuit is shown in figure 2b. At time t3, i.e at the end of said time delay, the high level of this signal is reached and the valve 29 will be opened delivering the pneumatic output signal c from the control unit cf., figure 3 (III). At the same time the valve 30 will be closed and the signal d returns to zero. Consequently the hydraulic valve 37 will also be closed. A leakage path is opened for the return pressure from the first moving system through the valve 37, the hydraulic restiction 34 and to the hydraulic accumulator 35. The booster 24 still delivers the amplified pressure on its output which is, however, now blocked by the valve 37. The leakage pressure from the first moving system back to the control unit is much lower which means that the checkvalve 36 is closed. By means of the restriction 34 it is possible to adjust the reverse speed of the piston X of the first moving system.

When the signal h raises, at time t4 as descriht' above, indicating the blocking of the anvil Y, the valve 2 will be opened, cf., figure 3 The regulated input pressure 1 will thus be tranferred through the OR-gate 33 to the valve 37 and open this valve once again giving the hydraulic output pressure g which will start the second stroke of the first moving system of the tool.

Finally, when the operator releases the trigger at time cf.figure 3 the signal a will return to zero and thej remaining pressure from the pressure accumulator 32 of the si" 1 11 i WO 89/07020 PCT/SE89/00037, 12 delay circuit will leak through the check valve parallell to the flow restiction 31 back to the trigger valve of the tool where it is exhausted. This means that the signal b returns to zero and the valve 29 will be closed. When closing it brings signal c to zero which in its turn closes valve 30 and brings the blocking member to return to its rest position. At this rest position the signal h will return to zero closing the valve 28 causing the hydraulic valve 37 to close.

When the valve 37 closes the leakage path for the first moving system through that valve is opened once again. Due to the fact that the signal f has dropped to zero the piston of the booster is now free to move upwards. When the pressure at the output of the booster has dropped to the same level as the pressure in the hydraulic accumulator the checkvalve 36 will open and connect a return oil flow from the accumulator and the first moving system of the teo.L back to the booster 24.

'Thus the final rest status is reached with all signals except the signal p at zero level and the operation cycle is completed Figure 4 shows a second embodiment of the control unit. The designations of corresponding components are the same. The main difference from what has been described above resides in the design of the hydraulic valve 37 here called 37' In thiL embodiment this valve is controlled by means of pneumatic pressure in both directions. When using such a valve it- is possible to dispose of the pneumatic OR-gate 33 and the valve 30, shown in the first embodiment. Therefore a control Unit according to figure 4 is cheaper. Tile two enodiments now described both operate with high pressure at the output from the booster during the Whole operation cycle of the todol.

SUBSTITUTE SHEET WO 89/07020 PCT/SE89/00037 In the figures 5 and 6 two other embodiments of the control unit are shown in which the output from the booster is not provided with a hydraulic valve. This means that in order to have the first moving system of tile tool making two strokes the piston of the booster has to make two strokes.

Now the air volume and consequently the corresponding pneumatic capacity in the booster is considerable which means that the stroke of the piston of the booster will be rather slow. Therefore, even if the two evLtbodiments according to figures 5 and 6 could deliver the same signals to the tool as described above, the time scale will be different.

In erder to have the possibility to adjust the speed of the backward movement of the first moving system of the tool like in the previously described embodiments it is in the exemples of figures 5 and 6 possible to introduce between the booster 24 and the valve 25 and 25' respectively a parallell combination of a checkvalve and an adjustable pneumatic restiction.

Of course many other configurations for tle control unit could be conceived giving the same sequense of output signals to the tool.

All the described embodiments of the control unit as Well as the tool itself take the necessary power from the pneumatic pressure source 38. Other types of power sources eog. electrical Q 4uld of course be envisaged for the tool and/or the logic. Especially for stationary machines it would be possible with for instance cam driven mechanical actuators for the moving parts.

The components 28, 33, 30, 31, 32, %9 of the first described embodimient of the control unit could for instance SUBSTITUTE 8HAET 4 WO 8907020PCT/5E89/00037.

14 be changed to electronic eqivalents and one of the Pneumatic pressure regulators of the unit 27 and 26 respectively could in that case be disposed of. In the tool the trigger could be an electrical trigger and the blocking ZI 6, 7, 8, 21 an electro magnetical unit giving ail electrical Output signal h. Such a system would give the same input and output signals Detween the tool and the control unit as shown in figure 2b although some of them would now be electrical.

A further envisaged embodiment has instead of the pressure booster 24 a hydraulic pump driven by an electrical motor.

A substitution of the trigger by a pedal or arranging the feed-back signal h to be taken out from the first moving system are examples of change8 within the general scope of this invention.

When describing the tool and the operation sequence of the same above it has been assumed that the resulting joint will be of the non-leak proof type. in the first stroke of the punch 12 this will cut through the two sheets 10,11 along part of the circumference of the punch. However, other types of joints could be produced by means of the desoribed method making use of a slightly different sets of punch, die and anvil in the tool. it is here referred to a leak proof type of joint of the same general. type as described in the EJS-A-4 459 735 mentioned obove in the description of the prior art, cf. figure 10, AS mentioned that system operates with only one stroke of the moving part of the machine and the die. has laterally moving parts.

In our system on the other hand the ma I' moving unit of the tool makes two strokes. The dimensions of the cooperating punch and die are sti.lh that the punch in the first stroke.

does not cut through any part of the sheets but makes a preferably cylindrical deformation by a drawing action SUBSTITUTE S4eEr i )IC i ~-iiiL l i e WO 89/07020 PCT/SE89/00037 mainly in the clearance between ,ihe punch and the die. By means of the anvil the deformed portions of the two sheets are then brought outside the die before the second stroke takes place. The free lateral extrusion of sheet material then takes place during the second stroke.

In figure 7 an alternative arrangement of the moving parts is shown. The same designations have been used for corresponding units. In this embodiment the die 9 is moved by the piston X towards the punch 12 in the first stroke.

The first predetermined relative position between die and punch is defined by the end position of the piston movement. The anvil Y is operated in the same way as described above. A joint which could be produced by .neans of this arrangement is shown in figure 8.

Two sections through such a joint is shown in figure 9.

Ij ii R j SUBSTITUTE SH;SP-js

Claims (8)

1. A method for joining together two or more overlaying sheet formed members; said method utilizing cooperating relative movements of a co-axial arrangement of a punch, die, and an anvil; one of said punch and oaid die comprising a movable element, and the other of said punch and said die comprising a fixed element; the steps of said method comprising: positioning said sheet formed members between said movable element and said fixed element, applying a force to said movable element for moving said movable element without providing any prior adjustment to the distance to be travelled by said movable element in a first movement in a first direction co-axially towards said S. fixed element and into a first predetermined position S: relative to said fixed element that is independent of the :"total thickness of said sheet formed members to be joined together, applying a force to said anvil for moving said anvil co-axially in a direction opposite to that of said first movement of said movable element into a second predetermined position relative to said fixed element that is independent of the total thickness of said sheet formed members to be joined together, blocking axial movement of said anvil in said second position, and joining said sheet formed members by applying a further force to said movable element for moving said movable element in a second movement in said first direction co-axially towards said anvil and into a third positiol for joining together by deforming said sheet formed members by forces applied thereto resulting from the movement of said movable element into said third position, i la i 1' j 17 17 said third position being dependent on said applied forces and on the number, thickness and material of said sheet formed members to be joined together.

2. An apparatus for joining together two or more overlaying sheet formed members positioned between a punch and a die; said apparatus including a punch, a die and an anvil; one of said punch and said die comprising a movable element, and the other of said punch and said die comprising a fixed element; said apparatus comprising: means for moving said movable element without providing any prior adjustment to the distance to be travelled by said movable element in a first direction of movement co-axially towards said fixed element and into a first predetermined position relative to said fixed element that is independent of the total thickness of said sheet e g formed members to be joined together, means for moving said anvil co-axially in a (i direction opposite to said first direction of movement of said movable element and into a second predetermined position relative to said fixed element that is independent of the total thickness of said sheet formed members to be S joined together, means for blocking axial movement of said anvil in r* said second position, and means for moving said movable element for providing a second movement of said movable element in said first direction co-axially towards said anvil and into a third position, said third position being dependent on applied forces and on the thickness, number, and material of said sheet formed members to be joined together. Y 18

3. A method for joining together two or more overlaying sheet formed members; said members utilizing cooperating relative movement of a co-axial arrangement of a punch, die, and an anvil; one of said punch and said die comprising a movable element, and the other of said punch and said die comprising a fixed element; the steps of said method comprising: positioning said sheet formed members between said movable element and said fixed element, applying a force to said movable element for moving said movable element without providing any prior adjustment to the distance to be travelled by said movable element in a first movement in a first direction co-axial relative to said fixed element and into a first predetermined position *relative to said fixed element that is independent of the jo t total thickness of said sheet formed members to be joined :together, applying a force to said anvil for moving said anvil co-axially relative to said fixed element and into a second predetermined position relative to said fixed element that is independent of the total thickness of said sheet formed members to be joined together, blocking axial movement of said anvil in said second position, and Sj ining said sheet formed members by applying a further fo ,e to said movable element for moving said movable element in a second movement co-axial relative to said anvil and into a third position for joining together by deforming said sheet formed members by forces applied thereto resulting from the movement of said movable element Sinto said third position, said third position being dependent on said applied forces and on the number, thickness and material of said sheet formed members to be joined together. I$ i Il c t dIvTV^ 19

4. An apparatus for joining together two or more overlaying sheet formed members positioned between a die and a punch; said apparatu.s including a punch, a die, and an anvil; one of said punch and said die comprising a movable element, and the other of said punch and said die comprising a fixed element; said apparatus comprising: means for movi.ng said movable element without providing any prior adjustment to the distance to be travelled by said movable element in a first direction of V movement co-axial relative to said fixed element and into a first predetermined position relative to said fixed element v that is independent of the total thickness of said viheet ti formed members to be joined together, means for moving said anvil co-axially relative to *said fixed element and into a second predetermined position relative to said fixed elemient that is independent of the total thickness of said sheet formed members to be joined V, togethe'r, means for blocking axial movement of said anvil in V said second position, and ii :.means for movinig said movable element for providing asecond movement of said movable element co-axial relative tsaid anvil and into a third position, said third position being dependent upon applied forces and on the thickness, number, and material of said sheet formed member's to he joined together.

The method acccovding to claim 1, characteriztd in that in said first, predetermined position, a tip of said punch is flush with a top surface o~l said die. 4 i

6. A method according to claim 1, characterized in that during said first movement of said movable element, a tip of said punch does not reach a plane through a top surface of said die, but stops at a predetermined distance from said plane.

7. A method according to claim l, characterized in that during said first movement of said movable element, a tip of said punch passes a plane through a top surface of said die and stops at a predetermined distance from said plane.

8. A method according to claim 1, characterized in o too: that in said second predetermined position, a tip of said anvil is flush with a plane through a top surface of said die. A method for joining together two or more overlaying sheet formed members substantially as hereinbefore described with reference to the accompanying drawings. t 10. Apparatus for joining together two or more overlaying sheet formed members substantially aa hereinbefore described with reference to the accompanying drawings. DATED this k!5th day of August 1991 ATTEXOR ZQUIPEMENTS S.A. WATERMARK PATENT TRADEMARK ATTORNEYS THE ATRIUM 290 BURWOOD ROAD HAWTHORN, VICTORIA 3122 AUSTRALIA LJD:AGB;KG 2(40) NT.0