EP0032868B1 - Method of and apparatus for making, by extrusion, a workpiece presenting a recessed part on its peripheral surface - Google Patents

Abstract

A device for manufacturing, by extrusion, a piece having a recessed portion in its lateral surface, and, on one side, a head and, on the opposite side, a tail, which device comprises a fixed die holder containing a die, a punch borne by a mobile support and structure for axially displacing the punch to engage it in the die and to disengage it therefrom together with means for ejecting the extruded piece. The device further comprises, in front of the fixed die holder, a coaxial mobile die holder composed of two parts, forming clamp. A spring and cooperating cams are provided for opening and closing the mobile die holder-forming clamp and an actuator is provided for displacing the mobile die holder in translation parallel to the axis of the punch and of the die. After the actual extrusion operation, the mobile die holder-forming clamp draws on the head of the extruded piece so as partially or totally to disengage its tail from the die, then the mobile die holder is opened so as to release the piece and allow ejection thereof.

Description

The present invention relates to a method and a device for manufacturing, by spinning, a part having a hollow part in its peripheral surface.

Spinning is advantageously used in the manufacture of parts in large series because it offers many advantages among which one can quote the obtaining of parts having an excellent finish, the saving of material since there is no loss and the manufacture in a single operation of parts having any cross section. This latter advantage is particularly advantageous in the case of very small parts obtained by microfilming, since it is not possible to obtain a polygonal cross section by bar turning. It is not possible to mill small hollow parts.

Although the spinning process has many advantages, it has not yet been able to be used so far for the manufacture of parts having hollow parts in their peripheral surface, for example transverse grooves. It is indeed necessary, so that one can eject a spun piece, that its cross section always varies in the same direction, to allow it to exit the die by being pushed by an ejector. Another limitation to the extension of the use of the spinning process is due to the fact that in the case of parts of small dimensions obtained by micro spinning, it is not possible to carry out the conventional ejection by spinning before which consists in pushing on the rod of the part by means of an ejector. Indeed, the part being of reduced dimensions, it is the same for the ejector and such an ejector would buckle under the effort to be made.

The present invention aims to remedy these drawbacks by providing a method and a device making it possible, by very simple means, to obtain by spinning small parts having hollow parts.

To this end, this method of manufacturing, by spinning, of a part having a hollow part in its lateral surface, this part comprising on one side a head and on the opposite side a tail, method in which a punch is engaged in a tubular blank and the blank is pushed by the punch into a die of a fixed matrix, is characterized in that the punch and the blank are engaged through a movable matrix placed in front of the fixed matrix then, after the operation of actual spinning, we pull, by means of the movable die forming a clamp, on the head of the extruded piece so as to release, partially or totally, its tail from the die, then the movable die is opened so as to release the and allow it to be ejected.

The invention also relates to a device for implementing the aforementioned method, comprising a fixed matrix containing a die, a punch carried by a movable support, means for axially displacing the punch to engage it in the die. disengage therefrom, and means for ejecting the extruded part, characterized in that it comprises, in front of the fixed matrix, a coaxial mobile matrix in two parts forming a clamp, means for opening and closing said mobile matrix forming clamp and means for moving the movable matrix in translation parallel to the axis of the punch and of the die.

The method and the device according to the invention offer the advantage that they make it possible to produce, by microfiltering or spinning, parts having, for example flanges, parts which it was impossible to obtain previously due to the difficulties of ejection of such rooms. It is thus easy to manufacture, at high speed, parts of small dimensions having any cross section and having a hollow part forming a groove. Furthermore, the parts obtained have an excellent surface quality and do not require an additional finishing operation.

• La figure 1 est une vue en coupe verticale d'une presse de filage mettant en oeuvre le procédé suivant l'invention.
• La figure 2 est une vue en perspective éclatée des deux bras de la pince formant la matrice mobile.
• La figure 3 est une vue en perspective de la matrice mobile fermée et du mandrin de serrage assurant sa fermeture.
• La figure 4 est une vue en coupe horizontale partielle faite suivant le ligne IV-IV de la figure 1, la matrice mobile étant fermée.
• La figure 5 est un schéma, à plus grande échelle, illustrant l'entraînement de la pièce filée par la matrice mobile, avant l'ouverture de cette dernière.
• La figure 6 est une vue en coupe horizontale semblable à celle de la figure 4, dans le cas où la matrice mobile est ouverte.

An embodiment of the present invention will be described below, by way of nonlimiting example, with reference to the appended drawing in which:

• Figure 1 is a vertical sectional view of a spinning press implementing the method according to the invention.
• Figure 2 is an exploded perspective view of the two arms of the clamp forming the movable matrix.
• Figure 3 is a perspective view of the closed movable die and the clamping mandrel ensuring its closure.
• Figure 4 is a partial horizontal sectional view taken along line IV-IV of Figure 1, the movable die being closed.
• Figure 5 is a diagram, on a larger scale, illustrating the drive of the part spun by the movable die, before the opening of the latter.
• Figure 6 is a horizontal sectional view similar to that of Figure 4, in the case where the movable matrix is open.

In Figure 1 is shown a tool holder 1 of a spinning press. This tool holder 1 comprises, at its lower part, a fixed die 2 inside which is mounted a die 3 of horizontal axis. The die 2 containing the die 3 protrudes relative to the bottom of a recess 4 which extends vertically and which is formed in the right front face of the tool holder 1. Next to the die 3 can move horizontally a support 5 of a punch 6 secured to a punch holder 7 fixedly mounted inside the support 5. On the punch 6 is slidably mounted an ejector 8 whose axial sliding movement can be caused by a thrust grain 9 acting on a thrust column 11 disposed between the thrust grain 9 and the ejector.

The spinning operation which must be carried out by means of the press illustrated in FIG. 1, is carried out on a tubular blank E which is brought in front of the punch 6, in the axis thereof, by a transfer device 12.

The extrusion press comprises, in addition to the fixed die 2, a movable die generally designated by 13, which is shown in detail in FIGS. 2 and 3. This movable die 13 consists of two jaws 14 and 15 of cross section substantially semi-circular. These two jaws 14 and 15 are applied one against the other when the die 13 is closed, the junction being carried out along a diametrical plane. The jaws 14 and 15 respectively carry, on the inside, respective transverse flanges 16 and 17 of semi-circular shape, having in their centers cutouts 16a and 17a also semi-circular, the two cutouts 16a, 17a form a circular hole , when the movable jaw 13 is closed, hole through which the tubular blank E is engaged during the spinning operation.

The transverse flanges 16, 17 can form a single piece with the body of the jaws 14 and 15 or constitute independent pieces attached to them, which allows them to be easily changed in the event of wear. The semicircular flanges 16, 17 define in the jaws 14 and 15, when the movable die 13 is closed, a housing in which the fixed die 2 is enganged as can be seen in FIG. 1.

According to the invention the jaws 14 and 15 are mounted movable relative to each other, so that the movable die 13 can open or close.

According to a nonlimiting embodiment shown in FIGS. 2 and 3, the jaws 14 and 15 are provided respectively at the ends of two arms 18 and 19 which are mounted articulated one on the other, around an axis ( FIG. 1) passing through opposite holes 22 and 23 drilled respectively in the arms 18 and 19. In the end parts of the branches 18a and 19a which are located opposite the jaws 14 and 15 are formed two semi-circular notches 24 and 25 which are applied one on the other, when the movable jaw 13 is closed, thus defining a hole through which is engaged the end of a horizontal axis 20 (Figure 1).

The two arms 18 and 19 are mounted in the manner of a pair of scissors. In other words, the branch 18a of the arm 18 which extends opposite the jaw 14 is located, in FIGS. 2 and 3, under the corresponding branch 19a of the arm extending opposite the jaw 15, while the jaw 14 is it above the jaw 15. These two branches 18a and 19a are pierced with respective blind holes 26 and 27 opening into the faces by which the branches 18a and 19a bear one on the other , and a compression spring 28 is housed in these blind holes 26 and 27. This spring 28 therefore tends to separate the branches 18a, 19a from one another, and in the same way from the jaws 14 and 15.

The assembly of the two arms 18 and 19, constituting a sort of clamp, is mounted movable in horizontal translation on the tool holder 1. In the rest position, in which the movable die 13 is closed, this assembly 18, 19 is retracted inside the recess 4 provided in the right vertical face of the tool holder 1, as shown in FIG. 1. The two axes 20 and 21 are mounted to slide horizontally in respective bearings 29 and 31 and they are biased to the left in Figure 1 by springs 32 and 33. These axes 20 and 21 are thus kept permanently applied against respective thrust grains 35 and 35 which are actuated by cams forming part of the general control mechanism of the machine.

The clamp constituted by the two arms 18 and 19 can be closed by the action of a clamping mandrel 36 which is fixed in the tool holder 1 by means of screws 37. This clamping mandrel 36 which extends horizontally, comprises a head 36a which projects into the recess 4.

This head 36a is cut so as to form a diametrical opening 38 substantially in a U. More particularly this opening, the width of which decreases from its entry towards its bottom, is delimited by two parallel and symmetrical plates 38a which are then connected, by ramps 38b inclined inwards, to two other blades 38c whose mutual distance is less than that between the two plates 38a, the two plates 38c being in turn connected to the bottom of the opening by two ramps 38d inclined towards the 'interior and same slope as the ramps 38b. The axial section of the head 38a of the clamping mandrel 36 is clearly shown in FIGS. 4 and 6.

In the closed position of the clamp formed by the arms 18 and 19 (FIGS. 1 and 4) the two branches 18a, 19a of the arms 18 and 19 are engaged at the bottom of the opening 38. It can be clearly seen in FIG. 4 that in this position the upper faces of the upper branch 19a and lower of the lower branch 18a are respectively supported on the two dishes 38c whose interval corresponds to the sum of the thicknesses of the two branches 18a and 19a. These two branches have, on the side facing the bottom of the opening 38, respective chamfers 18b, 19b whose slope corresponds to that of the ramps 38b and 38d. In the closed position the chamfers 18b, 19b are therefore in abutment against the ramps 38d. The clamp formed by the arms 18, 19 is engaged in the opening 38 of the clamping mandrel 36 under the action of a pusher 39 moved by the general control mechanism of the machine. We will now describe the operation of the spinning press which has just been described, during a complete spinning cycle. of a room.

At the start of the operating cycle, the movable matrix formed by the two jaws 14, 15 and the two transverse flanges 16, 17 is closed and it covers the fixed matrix 2 containing the die 3, as shown in FIG. 1. L the axis of the die 3 is located opposite the axis of the hole 16a, 17a of the movable matrix, this axis being itself aligned with that of the tubular blank E brought into position by the transfer device 12 and the punch 6.

The first step of the process, which constitutes the left hand spinning operation proper, consists in moving the block with the nut 5, towards in FIG. 1. During this movement the punch 6 engages in the bore of the blank E and pushes the latter to the left through the hole 16a, 17a of the movable matrix then into the die 3. This die 3 has an inlet opening with a diameter greater than that of the hole 16a, 27a, as can best be seen in FIG. 5. The engagement of the punch inside the tubular blank E causes the material of this blank to creep which then follows the profile of the die 3, as it appears on the Figure 5. We then obtain a spun piece 41 which acomporte a tail 41 engaged in the die 3, a head 41 located on the outside of the flanges 16, 17, a flange 41c formed by creep in the die and located on the inside of the flanges 16, 17 and a groove 41d delimited between the head 41 b and the flange 41 c, c andthroat conforming to the outline of the central hole 16a, 17a.

The following operation consists in a translational movement to the right of the movable clamp formed of the two arms 18 and 19, as well as of the support 5 of the punch 6 and of the plunger 39. For this purpose the cams of the general control mechanism of the machine act on the thrust grains 34, 35, to make them slide to the right in FIG. 1, which results in a simultaneous translation in this same direction of the axes 20 and 21 against the return springs 32 and 33 which are compressed in their housings. In the first part of this movement, the clamp formed by the arms 18 and 19 remains closed. It can be seen in FIG. 4 that the two branches 18a and 19a are kept applied one against the other by the flats 38c of the clamping mandrel 36. When the branches 18a, 19a arrive at the start of the inclined ramps 38b, they begin to move away from each other, sliding on these ramps, under the action of the compression spring 28 causing the opening of the clamp. This combined movement of opening of the clamp and translation continues until the branches 18a, 19a come into contact with the dishes 38a which are the most spaced apart. These dishes 38a then maintain the clamp in the open position. During this movement, on the other side of the articulation axis 21, similar movements take place. In other words, in the first part of the race (sliding of the branches 18a, 19a on the plates 38c) the two flanges 16, 17 remain applied one against the other, in other words the movable matrix 13 remains closed. This movable matrix then drives to the right the extruded part 41, as indicated in FIG. 5, the flanges 16 and 17 of the movable matrix exerting their force on the open head of this part. This movement makes it possible to partially or completely free the spun tail 41 a from the die 3.

Then, during the opening of the clamp formed by the arms 18 and 19 (sliding of the branches 18a, 19a on the ramps 38b to the dishes 38a), the two flanges 16, 17 move away from one of the other (as indicated by the arrows in Figure 5) so that the extruded piece 41 is released and remains on the punch 6. Then, the punch 6 continues to be driven to the right by its support 5 until that the extruded part 41 is completely disengaged from the die 3. It then suffices to slide the ejector 8 to the left on the punch 6 to cause the ejection of the extruded part. During this ejection operation, the general control mechanism of the machine returns the various mobile elements to their starting positions. The clamps are brought back by the return springs. The pusher 39 at the start of the cycle comes to tighten the clamps.

Although in the embodiment which has been described above, the movable matrix constituted by the two jaws 14 and 15 is formed at the ends of two arms 18, 19 pivoting about an axis, one could also, without leaving the frame of the invention, make a matrix with two jaws movable in translation, these jaws being integral with movable slides in appropriate slides so as to apply the two jaws against each other, when the matrix is closed, or, at on the contrary, to separate them from each other to release the extruded part.

The jaws can be part of an independent assembly which can be mounted on different types of machines. The principle concerns as well the movement of pliers, scissors type, as a principle of work in perpendicularity, that is to say a small press operation.

The hole which is delimited in the center of the movable matrix 13 by the notches 16a and 17a of the respective transverse flanges 16, 17 may be circular, as in the example described above, or else of polygonal cross section or of any other shape, according to the shape which it is desired to obtain for the groove 41 d of the extruded piece 41. The shape of this groove is in fact determined by that of the outline of the hole 16a, 17a, through which the blank E carried by the punch 6.

As emerges from the preceding description, the principle of the device according to the invention is to have an opening matrix system which is closed during work and which serves to remove the parts with external impressions and, after total or partial ejection, to release them on the punch.

This process is valid for all extruded materials.

It is not limiting as to the number of uses of this system on the same machine.

Claims (12)

1. A process for manufacturing, by extrusion, a piece (41) having a recessed portion (41 d) in its lateral surface, this piece comprising, on one side, a head (41 b) and, on the opposite side, a tail (41 a), in which process a punch (6) is engaged in a tubular blank (E) and the blank (E) is pushed by the punch (6) in a die (3) of a fixed die holder (2), characterized in that it comprises the steps of: - engaging the punch (6) and the blank (E) through a mobile die holder (13) placed in front of the fixed die holder (2) then, after the actual extrusion operation, - drawing, by means of the mobile die holder (13) forming clamp, on the head (41b) of the extruded piece so as partially or totally to disengage its tail (41 a) from the die (3), then opening the mobile die holder (13) so as to release the piece (41) and allow ejection thereof.

2. A device for carrying out the process of Claim 1, comprising a fixed die holder (2) containing a die (3), a punch (6) borne by a mobile support (5), means for axially displacing the punch (6) to engage it in the die (3) and disengage it therefrom, and means for ejecting the extruded piece, characterized in that it comprises, in front of the fixed die holder, a coaxial mobile die holder (13) composed of two parts forming clamp, means (36) for opening and closing said mobile die holder (13) forming clamp and means (20, 21, 34, 35) for displacing the mobile die holder (13) in translation parallel to the axis of the punch (6) and of the die (3).

3. The device of Claim 2, characterized in that the mobile die holder (13) is constituted by two jaws (14,15) applied against each other when the mobile die holder (13) is closed, these jaws (14, 15) being provided respectively at the ends of the two arms (18, 19) mounted to pivot on each other about a first pin (21) passing through opposite holes (22, 23) made in the arms (18, 19), the mobile die holder (13) thus constituting a clamp.

4. The device of Claim 3, characterized in that it comprises a spring (28) urging the two arms (18, 19) constituting the mobile die holder (13) in the direction of opening, i.e. spacing apart the jaws (14, 15).

5. The device of Claim 4, characterized in that the spring (8) is a compression spring housed in blind holes (26, 27) made in end parts (18a, 19a) of the respective arms (18, 19) which are located opposite the jaws with respect to the pivot pin (21).

6. The device of Claim 5, characterized in that the end parts (18a, 19a) of the arms (18, 19) opposite the jaws (14, 15) respectively present semi-circular notches (24, 25) or of any other form, applied one on the other when the mobile die holder (13) is closed and thus defining a hole through which is engaged the end of a second pin (20) parallel to the first pivot pin (21) for the arms (18,19).

7. The device of Claim 6, characterized in that the first and second pins (21, 20), parallel to each other, are mounted to slide in respective bearings (31, 29) and are urged by springs (31, 32) towards respective thrust discs (35, 34) actuated by cams.

8. The device of Claim 7, characterized in that it comprises a fixed clamp chuck (36) comprising a head (36a) cut out so as to form a substantially U-shaped diametrical opening (38) in which are engaged the two end parts (18a, 19a) of the arms (18, 19), opposite the jaws (14, 15), the width of the opening (38) being smaller near its bottom end than near its inlet so that the mobile die holder (13) is closed when the two end parts (18a, 19a) are in the bottom end of the opening and, on the contrary, open when these two end parts are close to the inlet of the opening.

9. The device of Claim 8, characterized in that the opening (38) of the head (36a) of the clamp chuck (36) is defined, at its inlet, by two first parallel and symmetrical flat portions (38a) which are joined, by first inwardly inclined ramps (38b), to two second flat portions (38c) of which the distance separating them is shorter than that between the two first flat portions (38a), the two second flat portions (38c) being in turn joined to the bottom end of the opening by two second inwardly inclined ramps (38d) of the same inclination as the first ramps (38b), the two end parts (18a, 19a) of the arms (18, 19) presenting, on the side facing the bottom end of the opening (38), respective chamfers (18b, 19b) whose inclination corresponds to that of the ramps (38b, 38d), the distance between the two second flat portions (18c) being equal to the sum of the thicknesses of the end parts (18a, 19a) so that the mobile die holder (13) is closed when the two end parts (18a, 19a) are located between the two second flat portions (18c).

10. The device of Claim 9, characterized in that the clamp formed by the arms (18, 19) is pushed in the opening (38) of the clamp chuck (36) under the action of a push member (39) mobile in translation.

11. The device of any one of Claims 3 to 10, characterized in that the jaws (14, 15) comprise respective transverse cheeks (16, 17) presenting, on their edges coming into contact, cut-outs (16a, 17a) forming a hole when the mobile die holder (13) is closed, through which is engaged the tubular blank (E) borne by the punch (6).

12. The device of Claim 2, characterized in that the two parts constituting the mobile die holder (13) form two jaws mobile in translation.

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