FR2742367A1 - Guide dowel for work in electro-discharge machine tool - Google Patents

Abstract

The guide dowel (9) is a cylindrical rod with a peripheral wall (10) externally limited by an external face (11) and internally by peripheral faces (12a-12d) of a central bore (13) extending longitudinally from end to end of the rod. The rod has an concave upstream inlet face and a downstream discharge face. The inlet face has a chamfered surface to guide and centralise the work. The rod has at least two cut outs (16a-c) formed by radial grooves extending longitudinally of the bore to open at one part towards the interior into the bore and towards the exterior of the front face. The grooves are disposed at angles on the internal peripheral faces.

Description

IMPROVED INTRODUCTION OF PROFILED BARS
IN A ROTATING DEVICE. ESPECIALLY ON TOUR A
TAKE OFF
The present invention relates to an improvement for a turning lathe intended to facilitate the introduction of a profiled bar, more particularly an orientation sleeve intended to position said bar in orientation during its introduction.

 The industry in general today uses a very large number of mechanical parts of all kinds. This is, for example, the case of the automotive or household appliance industry and many other fields.

 Machining by bar turning is, nowadays, a process for producing parts very widely adopted for the manufacture of metal parts which must be mass produced for the needs of our economy, in particular in the area mentioned above.

 Also, companies specializing in machining by chip removal have therefore intensified their production and have had to equip themselves with single-spindle, multi-spindle or numerically controlled automatic turning lathes.

 Thanks to these machines, the machined parts are obtained from a bar having a section suitable for obtaining the finished part, this section being able to be round, square, hexagonal and the like. For this purpose, the bar is introduced into the active part of the lathe proper, thanks to an automatic or manual interlocking, to be maintained and guided therein in order to be machined therein at the end by a set of suitable tools, retained by tool holders generally arranged in a fan or at the end.

 Thus, each of the bars must be engaged for its machining.

This operation does not pose too many problems when the bar to be introduced is of cylindrical section, but the introduction of a non-cylindrical bar such as, for example, of square, hexagonal or triangular section is not without problem because the pliers of clamping and the guide barrel rotate at high speed while the bar before being introduced is fixed. There is then formation of repeated shocks if the profile of the clamp does not touch in front of the profile of the bar and it is impossible for the latter to continue its progression to reach the machining phase.

 The present invention seeks to overcome the drawbacks mentioned above by proposing a device allowing instantaneous orientation of the bar during its introduction into the rotating elements such as the guide barrels and the collets.

 Thus, the invention relates to a guide and orientation sleeve for a turning lathe element such as a guide bush or a collet, which is characterized in that it is in the form of a cylindrical ring comprising a peripheral wall bounded externally by an external face and internally by the peripheral faces of a longitudinal central hole passing right through said socket which comprises an upstream transverse face and a downstream face of concave introduction upstream, that is that is to say towards the inside of the sleeve to constitute, with the peripheral wall, at least one engagement and recentering surface for the end of the bar, while at least two hooking and guide housings are provided constituted by radial grooves extending longitudinally to open, in a pan, inwards into the longitudinal central hole, and on the other hand, outwards from the downstream side on the surf ace of engagement and refocusing, said grooves being arranged at the corners of the internal peripheral faces.

 According to an additional characteristic, the cross section of the central hole is identical in its forms and in its dimensions to the cross section of the bar intended to be introduced therein.

 According to another characteristic of the invention, the attachment grooves are rectangular or square sections, while they advantageously extend over the entire length of the central hole.

 Other characteristics and advantages of the invention will emerge from the description which follows with reference to the appended drawings which are given only by way of nonlimiting examples.

 Figure 1 shows a lathe equipped with sockets according to the invention.

 Figure 2 is a schematic view showing the bar before its introduction into the guide bush or the collet.

 Figure 2a is a sectional view along A-A of the bar.

 Figure 3 is a schematic view showing the bar during machining after its introduction into the guide bush or the collet.

 Figures 4, 5, 6 and 7 illustrate an embodiment of an orientation socket given by way of example, said socket being, in this embodiment, suitable for a bar whose cross section is square.

 Figure 4 is a perspective view.

 Figure 5 is an end view.

 Figure 6 is a longitudinal sectional view along B-B.

 Figure 7 is a longitudinal sectional view along C-C.

 Figures 8, 9, 10 and 11 schematically illustrate the process of introducing the bar.

 Figures 12 and 13 show an alternative embodiment of a socket adapted for a bar whose section is hexagonal.

 Figure 12 is a longitudinal sectional view along D-D.

 Figure 13 is an end view.

 FIG. 1 schematically illustrates an automatic lathe bearing the general reference (1) which can be of the single spindle or multiple spindle type. In these towers, the finished or semi-finished parts are obtained by various machining operations carried out at the end (2) of a bar (3) rotating at high speed on itself. Thus, the lathe itself (1) comprises a supply device (4) for bars arranged upstream, each bar being guided and retained to undergo the various machining operations such as turning, drilling, grooving, shaving, milling, chamfering, threading, and the like, such as parting off, said machining operations being carried out by a set of suitable tools (5) arranged, for example, in a fan or at the end, at the free end (2) of the bar (3) to be machined which projects beyond the clamp (6) and / or guide (7).

 As we have already specified above, the bar intended to be machined is introduced by translation along F during its feeding into different elements animated by a rotational movement (R) such as collet (6), guide barrel (7).

 The invention relates to a refocusing, guiding and orientation sleeve (9) intended to equip the guide bushes (7) and the traditional collets (6) or any other rotating element.

 FIG. 2 schematically illustrates the introduction of a bar (3) into a guide bush or a collet (6-7). Thus, the bar (3) is moved in translation along F to be introduced into the central hole of said barrel (7) or of said clamp (6) which is driven by a permanent rotational movement (R). Once the bar (3) is inserted, the latter (3) rotates with its guide barrel or its collet (6, 7) while its end (2) projects to be machined, as illustrated in the Figure 3. The refocusing and orientation sleeve bears the reference (9) and is intended to facilitate the introduction of the bar, as we will see below.

 In the embodiment which we will give by way of example, the bar (3) will be of square section but the invention applies, of course, also for other types of bar sections such as triangular, hexagonal, orthogonal or other. The sleeve (9) according to the embodiment of Figures 4 to 7 will therefore be described for engagement and orientation of a bar (3) of square section.

 This socket (9) is in the form of a cylindrical ring with an axis (xi ') comprising a peripheral wall (10) limited externally by an external cylindrical face (11) and internally by the peripheral faces (12a, 12b, 12c, 12d) of a longitudinal central hole (13) passing right through said orientation bush.

Said central hole (13) is intended to guide the inserted bar and therefore has a cross section identical in shape and in dimensions to the cross section of the bar. Also, in the example as illustrated, the longitudinal central hole (13) has a square section whose dimensions are, at play close to operation, those of the bar (3).

 The sleeve (9) comprises a transverse upstream face (14) and a downstream introduction face (15), said transverse upstream face (14) being plane and perpendicular to the axis (XX ') to constitute a transverse abutment surface and support for its mounting in the guide barrel or the collet, while the downstream introduction face (15) is concave upstream, that is to say towards the inside of the sleeve to constitute with the peripheral wall at least one surface (150) for engagement and refocusing for the end of the bar (2), this surface being advantageously conical.

 According to one characteristic, at least two attachment and guide housings (16a, 16c) are provided and, in this case and according to the example proposed, four attachment and guide housings (16a, 16b, 16c, 16d), each of these housings being constituted by radial grooves extending longitudinally to open, on the one hand, inwards into the longitudinal central hole (13) and, on the other hand, outwards from the side downstream on the engagement and refocusing surface (150) and on the other hand on the transverse upstream face (14). Note that the grooves are arranged at the corners of the internal peripheral faces.

 Figures 8 and 9 illustrate the introduction process.

 Thus, when the end (2) of the bar and more particularly its end face (21) comes into contact with the surface (150), FIG. 8, the latter is automatically refocused by said surface (150), FIG. 9 .

Thus, during the introduction of the bar, if its axis (X1X'1) is not perfectly in the axis (X) C) of the guide bush or the collet (6, 7), the refocusing will be done by the action of the surface (150) then serving as a refocusing ramp.

 During the longitudinal displacement downstream of the bar, at least one of the end angles (20a, 20b, 20c, 20d) will be hooked by at least one of the radial grooves (16a, 16b, 16c, 16d) which will cause, on the one hand, the setting of the bar in a good orientation allowing it to engage in the central hole (13), and on the other hand, its immediate rotation (see Figure 10) even before that the end of the latter is not fully engaged in said longitudinal central hole.

Each of the end angles will therefore find in front of it a corresponding groove, the bar then being perfectly oriented relative to the axial hole and its introduction by displacement along F will therefore be possible without shock or vibration.

 Figures 12 and 13 show an alternative embodiment of a socket (9) intended to be used for the orientation of a bar of the type whose section is hexagonal. To this end, said socket no longer comprises four attachment housings as previously but six longitudinal grooves (16a, 16b, 16c, 16d, 16e, 16f). Furthermore, in this embodiment, the downstream face (15) comprises a succession of conical engagement and guide surfaces. Namely, a first conical surface (150) followed by a second surface (151) extended by a cylindrical surface (152) followed by a third conical surface (153) onto which the six hooking grooves (16a, 16b) open. , 16c, 16d, 16th, 16f).

 Advantageously, the grooves or attachment housing (16) are of rectangular or square section and extend over the entire length of the central hole (13).

 Of course, the longitudinal grooves may extend only over a part of the length of the socket so, for example, that it does not lead to the upstream face (14), without thereby leaving the framework of the invention.

 Of course, the invention is not limited to the embodiments described and shown by way of examples, but it also includes all the technical equivalents and their combinations.

Claims (5)

 1. Guide and orientation sleeve (9) for turning lathe element (1) such as guide barrel (7) or collet (6), characterized in that it is in the form of a cylindrical ring comprising a peripheral wall (10) bounded externally by an external face (11) and internally by the peripheral faces (12a, 12b, 12c, 12d) of a longitudinal central hole (13) passing right through said bushing which comprises a transverse upstream face (14) and a downstream introduction face (15) concave upstream, that is to say towards the inside of the bushing to constitute with the peripheral wall at least one surface ( 150) of engagement and of refocusing for the end of the bar (2), while at least two hooking and guide housings (16a, 16c) are provided, constituted by radial grooves extending longitudinally for lead, on the one hand, inwards into the longitudinal central hole (13), and on the other On the other hand, towards the outside on the downstream side on the engagement and refocusing surface (150), said grooves being arranged at the corners of the internal peripheral faces (12a, 12b, 12c, 12d).  2 guide and orientation sleeve according to claim 1, characterized in that the cross section of the central hole (13) is identical in shape and in dimensions to the cross section of the bar (3) intended to be introduced therein .  3 guide and orientation sleeve according to claim 2, characterized in that the attachment grooves (16) are rectangular or square sections.  4. Guide and orientation sleeve according to claim 3, characterized in that the attachment grooves (16) extend over the entire length of the central hole (13).  5. Guide and orientation sleeve according to claim 2, characterized in that said transverse upstream face (14) is plane and perpendicular to the axis (XX ') to constitute a transverse abutment and support surface for its mounting in the guide bush or the collet.