EP1851001B1 - Transfer machine for producing drills and bits - Google Patents

Abstract

The machine has a combined terminal carrying out loading, sizing and sharpening operations in the respective terminals. The terminal has a single base (8) and a cylindrical spindle mounted on a movable composite support. The support has a circle sector (16) rotating around a swivel axis (19) on a movable table (10) that is mounted on a horizontal slide (9) of the base. Two coaxial grinding wheels are fixed on the axis of the spindle.

Description

Technical area

The present invention relates to a transfer machine for producing bits or drills.

Background of the invention

The transfer machines comprise several stations arranged to simultaneously perform various operations in automated sequences. This is particularly the case for machines intended to ensure the production in large series of small diameter parts such as bits or drills specially designed for so-called PCB operations or the drilling of printed circuits. The production of such drills, intended for consumer industries, requires machines capable of ensuring their production under conditions of efficiency and precision as high as possible.

• chargement de l'ébauche de foret
• taillage du filet (goujure)
• affûtage
• détalonnage
• dégagement arrière (aussi appelé undercut)
• contrôle de l'outil
• déchargement.

The successive operations that these machines must perform at each cycle are as follows:

• loading the drill bit
• cutting of the net (flute)
• sharpening
• undercut
• rear clearance (also called undercut)
• tool control
• unloading.

The document US-2003/060133 describes a single station machine where all the planned operations take place successively on the same blank.

Transfer machines at four or even five stations are common and we know that it is wise to organize the sequence of operations so as to use only a few stations and to distribute the different operations according to their durations, so that the time of the complete cycle ensures an optimal productivity.

These rules place the designer in front of a certain number of difficulties, the solutions which appear judicious encountering in certain cases practical impossibilities. In the case of the production of small diameter drills, the loading, the control and the unloading can be grouped on the same station equipped with a manipulator robot, but the use of a machine with four stations is then only possible. through a recovery operation for the rear clearance.

• Station 1 : chargement
• Station 2 : taillage
• Station 3 : affûtage
• Station 4 : détalonnage et dégagement arrière
• Station 1 : contrôle de bris d'outils et déchargement.

In order to overcome this difficulty, the present invention proposes a transfer machine in which the offsetting and the rear clearance are made in the same station so that the complete production cycle can be carried out in four stations. The sequence of operations is detailed as follows:

• Station 1: loading
• Station 2: cutting
• Station 3: sharpening
• Station 4: Calibration and Rear Clearance
• Station 1: control of broken tools and unloading.

Summary of the invention

To this end, the present invention relates to a transfer machine at several stations for machining drills characterized in that , to perform successive operations of relief and rear clearance on said drills, it comprises a combined station having a base unique and performing both operations in the same position of this base.

The said combined station preferably comprises a rotating spindle mounted on a movable composite support subjected to the action of a numerical control, two coaxial grinding wheels being fixed on the axis of the spindle.

According to one embodiment, the movable composite support comprises a circle sector mounted to pivot about a vertical axis on a mobile table on the base, a vertical structure integral with the circle sector and a vertical sliding slider on the said structure and carrying the pin, the axis of the latter being horizontal.

One of the two wheels fixed on the axis of the spindle may be a grinding wheel, the arrangement of the composite support being such that the pivot axis of the circle sector intersects the axis of the spindle in the plane of the spindle. this millstone.

The table may be mounted on a horizontal slide moving in a direction which, for a given position of the circle sector, is parallel to the axis of the spindle, the slide being supported and guided by said base.

The table mounted on the horizontal slide of the base may comprise a plurality of arcuate grooves centered on the pivot axis of the circle sector, the latter being equipped, in its face facing said table, locking pistons profiles T engaged in said grooves for blocking (passive) sector.

The second grinding wheel can be a rear release grinding wheel and can be fixed coaxially in front of the grinding wheel on the axis of the spindle, the said position determined from the circle sector is that corresponding to the rear clearance operation, the spindle axis being parallel to the direction of movement of the horizontal slide on the base.

The circle sector can be connected to the table by a vertical pivot axis, locking pistons and by a drive system supported by the table, itself consisting of a notched pinion motor with a vertical axis placed between two tensioning gears, and a belt pressed against the arcuate sector slice, fixed at both ends to this slice and passing into the drive system formed by the notched pinion and its two tensioning gears, the system of driving the circle sector which can be arranged in such a way that, by rotation of this sector about its axis of rotation, the axis of the grinding spindle can be brought into an orientation which makes with the direction of movement of the slide horizontal an angle corresponding approximately to the inclination of the turns of the threads of the drill relative to the axis of the latter, so as to go from the operation of the calibration to the operation of rear clearance re or vice versa.

The circle sector rotation drive system may have a numerically controlled motor, the control of the back-off and back-off operations being incorporated into a fully automatic transfer machine control program enabling the automated production of the drills.

Brief description of the drawings

• la fig. 1 est une vue en élévation latérale d'un foret,
• la fig. 2 est une vue en perspective d'une partie de la machine transfert montrant la station combinée, sans la broche,
• la fig. 3 est une vue en plan de dessous, montrant le secteur de cercle portant le socle de la broche, avec ses moyens d'entraînement,
• la fig. 4 est une vue partielle, en perspective, à échelle agrandie, montrant la broche montée sur son socle,
• les fig. 5 et 6 sont des vues en perspectives de la station combinée dans ses deux positions de travail, la base et la coulisse horizontale étant dans les mêmes positions, et
• la fig. 7 est une vue d'ensemble d'une machine transfert comportant la station combinée illustrée à la fig. 2.

An embodiment of the machine according to the invention is described below by way of example, the parts of this machine necessary for the understanding of the operations being shown in the appended drawing, in which:

• the Fig. 1 is a side elevation of a drill,
• the Fig. 2 is a perspective view of a part of the transfer machine showing the combined station, without the spindle,
• the Fig. 3 is a plan view from below, showing the circle sector carrying the base of the spindle, with its drive means,
• the Fig. 4 is a partial view, in perspective, on an enlarged scale, showing the pin mounted on its base,
• the Fig. 5 and 6 are perspective views of the combined station in its two working positions, the base and the horizontal slide being in the same positions, and
• the Fig. 7 is an overview of a transfer machine with the combined station illustrated in Fig. 2 .

Detailed description of the invention

An example of a transfer machine according to the invention is shown in FIG. Fig. 7 . This transfer machine comprises a loading station 51, a cutting station 52, a sharpening station 53 and a combined recalibration and rear clearance station 54. A rotary table 55 is disposed at the center of the machine and comprises in particular four door clamps. -Parts 56, 57, 58 and 59, intended to simultaneously present four drill bits to the tools of the four stations of the machine.

The drills 1 are mounted in the workpiece clamps of the transfer machine so as to be presented to the tools of the various stations and perform certain rotational movements, according to the programs provided. Each drill has a cylindrical rod 1 ( Fig. 1 ) on which one recognizes the different effective surfaces which appear once all the operations ended. Their denominations are as follows: a helical guide surface 2 divided into two narrow strips, called cylindrical indicators, two flutes 3, resulting from the helical cut, two cylindro-ogival surfaces 4 of relief at the active end of the part , a cylindrical surface 5 of diameter slightly smaller than that of the surfaces 2, forming the rear clearance, this surface being reduced to two helical strips by the goujurage 3 and extending to the rear end of the piece, two portions of surfaces 6 prolonging the relief and corresponding to a secondary sharpening and two pyramidal surfaces 7 extending the guide surfaces 2 and corresponding to a primary sharpening of the tip. All these surfaces are formed by appropriate grinding wheels in the various stations of the machine as indicated above.

We now describe the combined station 54 of recalibration and rear clearance, shown in perspective at the Fig. 2 . A fixed base 8 carries a horizontal slide 9 which, when the workpiece 1 and the combined station are in the relative position of rear clearance, moves parallel to the axis of the workpiece. On the slide 9 is fixed a table 10 whose flat upper surface has four grooves 11, 12, 13, 14 to rail profile, concentric, of different lengths, and of different diameters. At its rear end the table 10 carries a motor frame 15 containing, as will be seen later, a drive motor with notched pinion vertical axis and two pinions tensioners for moving a quarter-circle plate 16 forming part of a movable composite support on which the grinding spindle is mounted. The rotating circle sector 16, also visible to Fig. 3 to 7 , comprises a radial branch 17. At its end thereof is pierced with a hole for the engagement of a vertical axis pivot 19 fixed to the table 10 precisely at the central point of the grooves 11 to 14. The Fig. 3 shows this layout in detail. The circle sector 16 carries on its rear face four locking pistons 20, 21, 22, 23 T-profile each engaged in one of the grooves 11, 12, 13 and 14. The rotation of this part 16 is perfectly guided concentrically to the axis 19 by the sliding of its lower face on the upper face of the part 10. The lateral surface 18 of the circular sector 16 is a cylindrical surface forming its edge, also centered on the axis 19 and against which is supported a toothed belt 24 whose two ends are fixed at the points 25 and 26 on the right-angled sides of the part 16 leaving sufficient free length for the belt 24 to pass on the notched pinion 27 and the tensioning pinions 28 and 29 of the circle sector drive system 16 ( Fig. 3 ). We understand that the frame 15 ( fig.2 ) contains a drive motor 49 with a control circuit capable of rotating the driving pinion 27 and rotating at will the circular sector 16 of the movable composite support carrying the pin. This operation is carried out with great precision around the axis of the pivot 19.

Referring to Fig. 2 and 4 it can be seen that the hinged circle sector 16 carries a prismatic support 30 equipped with a vertical slide 31, the movable portion of which comprises a flat plate 32 to which is fixed a spindle support 33 with an articulated lid 34 locking by means of a mechanism 35, which fixes a cylindrical pin 36 so that its axis is perfectly horizontal with respect to the plane rotating sector 16. At its front end, the axis of the spindle 36 carries a drive disk 37, seen partially in section at the Fig. 4 and which is integral with a tip 38 with a central extension. Said end piece 38 is arranged so as to form a first pair of surfaces, namely a front surface 39b and an outer cylindrical surface 39. The extension of the endpiece further comprises a housing arranged to form a second pair surfaces, namely an inner cylindrical surface 40, parallel to the surface 39, and a front surface 40b, parallel to the surface 39b. The first pair of surfaces serves as a seat for a first profiled grinding wheel 41 while the second pair of surfaces receives and guides the rear portion of a hub 42 supporting on its cylindrical seat 43 a second profiled grinding wheel 44. A shoulder screw 45 rear and two nuts 46 and 47 respectively fix the hub 42 and grinding wheels 41 and 44 relative to the end piece 38 itself secured to the disc 37. The control of the motor 48 of the spindle drive 36 is incorporated in the control programmed general transfer machine. The two wheels 41 and 44 are perfectly centered on the axis of the spindle, which is itself horizontal. The grinding wheel 41 is adjusted for the relief operation. The axis 19 is in the plane of this wheel and cuts the axis of the spindle. Wheel 44 performs the back clearance operation. It is placed at a distance from the wheel 41 sufficient for the radial displacement of the horizontal slide 9 allows the rear clearance along the entire length of the room. The positions of the various organs of the combined station during the two operations are represented at Fig. 5 and 6 . The position of the Fig. 5 corresponds to the calibration. The workpiece being parallel to the direction of movement of the horizontal slide, the angle of the plane of the grinding wheel 41 corresponds to the inclination of the helical surfaces 2. The spindle can be raised or lowered during the operation, if necessary , so as to realize the surfaces 4. For the rear clearance, bring the spindle into the position of the Fig. 6 , its axis being parallel to that of the part. The plane of the wheel 44 is then perpendicular to this axis and the displacement of the horizontal slide, combined with the rotation of the tool, ensures the removal of material on the periphery of the core of the drill, to the desired depth for the formation of surfaces 5.

As can be seen, one of the advantages of the present invention is that it makes it possible to add to a transfer machine of a proven type elements which ensure two different operations in the same station. In particular, in the transfer machines for the production of small diameter drills, the cutting and sharpening operations are the most time-consuming. On the other hand, the offsetting operation, which consists of a short removal of material over a short distance, as well as the rear clearance operation which consists of a small removal of material, both only require operating times. reduced, the sum of which is less than or equal to the cutting or grinding time. The possibility of grouping the two operations of recalibration and rear clearance in the same station is therefore judicious. In other words the idea of producing a combined station performing two successive and distinct operations makes it possible to organize the work of the machine by improving the overall efficiency, while maintaining the precision qualities of the basic machine. It is enough that this last is a machine with four stations. Moreover, the general conformation of the machine is not critical. The stations can be mounted on a carousel of vertical or horizontal axis, rotating around the workpiece clamp or arranged differently.

Claims (11)

1. Transfer machine with several stations intended for machining of drills, characterised in that, in order to perform the consecutive operations of relieving and undercutting on said drills, it comprises a combined station (54) with a single base (8) which performs both these operations in the same position of this base.
2. Machine according to claim 1, characterised in that said combined station comprises a rotating spindle (36) mounted on a mobile composite support (9, 10, 16, 30, 32) subjected to the action of a numerical control, and in which two coaxial grinding wheels (41, 44) are fixed to the axle of the spindle.
3. Machine according to claim 2, characterised in that the mobile composite support comprises a sector of a circle (16) mounted so as to pivot around a vertical axis (19) on a table (10) that is mobile on the base (8), a vertical structure (30, 31) solidly attached to the circle sector (16) and a vertical slide (32), mobile on said structure (30, 31) and supporting the spindle (36), the axle of the latter being horizontal.
4. Machine according to claim 3, characterised in that, one (41) of the two grinding wheels fixed on the axle of the spindle being a relieving wheel, the layout of the composite support is such that the pivoting axis (19) of the circle sector (16) crosses the axle of the spindle in the plane of this grinding wheel.
5. Machine according to claim 3, characterised in that the table (10) is mounted on a horizontal slide (9), which moves in a direction that, for a determined position of the circle sector, is parallel to the axle of the spindle, the slide (9) being supported and guided by said base (8).
6. Machine according to claim 3, characterised in that the table (10) mounted on the horizontal slide (9) of the base (8) comprises several grooves in a circular arc (11 to 14) centred on the pivoting axis (19) of the circle sector, the latter being equipped, on its side that faces said table, with blocking pistons (20 to 23) with T-shaped profiles inserted in said grooves so as to assure the (passive) blocking of the sector (16).
7. Machine according to claims 4 and 5, characterised in that, the second grinding wheel (44) being an undercutting wheel and being fixed coaxially in front of the relieving wheel (41) on the axle of the spindle (36), said determined position of the circle sector is the position that corresponds to the undercutting operation, the axle of the spindle being parallel to the direction of movement of the horizontal slide (9) on the base (8).
8. Machine according to claims 4 and 5, characterised in that the circle sector (16) is connected to the table (10) by means of a vertical pivoting axis (19), a series of blocking pistons (20 to 23) and a driving system (15) supported by the table, which in turn consists of a motor (49) with a notched pinion (27) on a vertical axle placed between two idler sprockets (28, 29), and a belt (24) placed against the arc-shaped edge (18) of the circle sector (16), fixed by its two ends to this edge and passing through the driving system formed by the notched pinion and its two idler sprockets.
9. Machine according to claim 8, characterised in that the system (15) for driving the circle sector (16) is arranged so that, by rotation of this sector around its pivoting axis (19), the axle of the wheel-holding spindle can be driven in a direction that forms, together with the direction of movement of the horizontal slide (9), an angle that corresponds, approximately, to the tilt of the coils of the threads (2) of the drill in relation to the axis of the latter, so as to pass from the relieving operation to the undercutting operation or vice-versa.
10. Machine according to any one of the preceding claims, characterised in that the system (15) for driving the rotation of the circle sector (16) has a motor (49), which is numerically controlled.
11. Machine according to claim 10, characterised in that the control of the relieving and undercutting operations is included in an entirely automatic programme for controlling the transfer machine, which enables the automatic production of drills.

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