WO1999008833A1 - Pallet changer - Google Patents

Abstract

The invention relates to a pallet door (44) for a rotating pallet changer (16), in which a partition wall (46) placed between two pallets (19, 20) can swivel with at least one segment of the peripheral wall (49, 50) surrounding one of the pallets. The peripheral walls and the partition walls are supplemented by a compartment surrounding, at least partially, a workpiece holder to form a closed processing chamber.

Description

 description

PALLET CHANGER

The invention relates to a pallet changer according to the preamble of patent claim 1.

Cooling lubricants are usually supplied during the machining of workpieces, on the one hand to increase the stability of the tool through cooling and lubrication and on the other hand to dissipate the heat introduced into the workpiece and into the tool as quickly as possible from the machining point.

The automotive industry has started to use engine, chassis or body components made of light metals, preferably of aluminum or magnesium alloys. The processing of such magnesium-containing alloys is, however, relatively problematic, since the processing chips are easily flammable, so that a relatively high effort has to be made to maintain the required production security. The use of cooling lubricants based on water-based bases is only possible to a limited extent, since magnesium reacts with these components, so that oil-containing cooling lubricants must be used. However, such oil-containing cooling lubricants frequently adhere to the workpiece to be machined, so that it has to be cleaned with suitable cleaning agents after machining. The agents used for cooling and cleaning have to be disposed of or separated after the processing / cleaning cycle, which is relatively expensive. In order to overcome these disadvantages, there is an increasing tendency to process the workpieces dry, ie without coolant. It is essential in this processing that the processing chips are transported away from the workpiece as quickly as possible during the machining process. To ensure this, the machine tools used for dry machining are equipped with closed machining chambers in which the workpiece to be machined is located and into which the work spindle of the machine tool is immersed.

In special cases, the machining in the processing chamber can still take place under inert gas, so that operational reliability is increased.

Such machining centers for drilling and milling are expanded into flexible production cells by equipping them with pallet changers and pallet stores. In the known pallet changing devices, a basic distinction is made between pallet changers with a linearly acting pallet shifting station and pallet changers which are designed as swivel changers. Both systems work with at least two pallets, one of which is in a machining position in which it is clamped on a workpiece carrier, and the other in a transfer position in which a workpiece to be machined is clamped, which is then processed after machining the one workpiece can be swiveled into the machining position without a time delay. These measures reduce the chip-to-chip time compared to machine tools without a pallet changer.

1, to which reference is already made, shows a plan view of a machining center 1 in which a spindle carrier 2 which can be moved in the X and Y directions (perpendicular to the plane of the drawing) is guided by a cross guide on a nem stand 4 is guided. The spindle carrier 2 carries a horizontal work spindle 6 for receiving a machining tool.

The machining center 1 also has a tool changer, which can be designed, for example, as a drum magazine 8 arranged laterally, in which the tools 10 to be fed to the work spindle 6 are accommodated.

A workpiece carrier (table) 12 of the machining center 1 is mounted on a machine bed, not shown, in the feed direction (Z). The workpiece carrier 12 and the work spindle 6 are surrounded by a machining chamber 14, so that dry machining is made possible. To reduce the chip-to-chip times, a pallet changer 16 is assigned to the workpiece carrier 12, in which two pallets 18, 20 are mounted on a swivel device 22.

In the position shown in FIG. 1, the pallet 18 is in its processing position, in which it is clamped on the workpiece carrier 12 by means of suitable clamping means.

The other pallet 20 is located in a loading area in the transfer position, in which a previously machined workpiece can be removed and a workpiece to be machined can be clamped.

The pallet changer 16 carries a swing door 26, hereinafter called partition 26. Together with the side walls 15 and the arcuate walls 24 of the processing chamber 14 which are curved in a circular arc, this forms a complete encapsulation of the working area, which permits wet and dry processing. The pallet changer 16 has furthermore an arcuate sliding door 25, which closes a loading area for the pallet 20 and which serves as operator protection when changing the pallet.

The partition wall 26 lies sealingly against the peripheral wall 24, so that the space in which the pallet 18 located in the processing area is located is separated from the workpiece loading area in which the other pallet 20 is arranged.

The closed processing chamber 14 is thus limited by the side walls of the cabin which extend along the guide for the workpiece carrier 12, the upper half of the peripheral wall 24 and the partition wall 26 in FIG. 1. The latter is mounted on the swivel device 22, so that the partition 26 is rotated by 180 ° when the pallets are swiveled.

A disadvantage of the embodiment shown in FIG. 1 is that the volume encompassed by the peripheral wall 24 and the partition wall 26 is comparatively large, and reliable removal of chips from the processing chamber 14 is difficult.

In contrast, the invention has for its object to provide a pallet changer in which the processing space is reduced to a minimum.

This object is achieved by a pallet changer with the features of patent claim 1.

The circumferential walls and the partition wall are pivoted together by the measures according to the invention, so that the geometry of the peripheral walls is no longer adapted to the pivoting radius of the partition wall. that must, but can essentially be designed according to the pallet shape, so that the space encompassed by the peripheral walls is reduced to a minimum. The processing chamber can thus be considerably reduced in size compared to the conventional solution, so that the dead space of the processing chamber is less and thus chip removal is facilitated and the risk of ignition is reduced.

In a particularly preferred variant, the partition and the peripheral wall jointly form an H-shaped body, the two legs of the H being formed by the peripheral walls and each encompassing one of the two pallets at a small parallel distance.

In this exemplary embodiment, it is preferred if the peripheral walls and the partition wall are formed in one piece, so that no sealing problems occur in the transition region between the partition wall and the peripheral wall. The side edges of the H-legs are provided with sealing edges and, together with the side walls of the cabin surrounding the workpiece carrier guide, form a closed processing chamber.

In an alternative embodiment, the side walls are formed by two U-legs, which are displaceable along their longitudinal axis with respect to the partition, so that the two U-legs can partially encompass one of the two pallets. In principle, an H is formed by the longitudinal displaceability of the two U-legs over a pallet changing cycle, so that practically the same principle is used as in the solution described above.

The U- or H-shaped pallet door, consisting of a partition and associated peripheral walls, can be means of a lifting device in the vertical direction from a straightening position so that the pivoting can take place without sliding the peripheral edges on the cabin floor.

The construction is particularly simple if the above-described door of the pallet changer is provided with telescopic sections on which the lifting device engages, so that not the entire door but only the telescopic sections are raised.

In order to simplify the sealing on the roof area of the processing chamber, this area can also be formed with telescopic sections of the door, on which an actuating device acts for lowering, so that the door can be freely pivoted together with the pallets, without on the roof or the To rest the contact surface of the processing chamber.

Sealing to the immovable part of the processing chamber also takes place via seals, which are advantageously arranged on the side edges of the fixed parts of the cabin wall.

Advantageous further developments of the invention are explained in more detail below with the aid of schematic drawings. Show it:

Figure 1 is a plan view of a machining center with a conventional pallet changer.

2 shows a three-dimensional representation of a tool changer according to the invention; 3 shows a plan view of the tool changer from FIG. 2; and

4 shows a schematic diagram of a further exemplary embodiment of a pallet door for a tool changer.

FIG. 2 shows a schematic three-dimensional representation of a pallet changer 16, which can be assigned to a machine tool, for example a machining center 1 according to FIG. 1.

The pallet changer 16 according to the invention is mounted about a pivot axis 28 running parallel to the Y direction (FIG. 1) via a support frame 30 on a machine bed, not shown, of a machine tool, for example a machining center. On the support frame 30, a vertically extending pivot shaft 32 (coaxial to the pivot axis 28) in the illustration according to FIG. 2 is mounted, to which a cross member 34 is attached.

The swivel shaft 32 is driven by a swivel motor 36 arranged in the radial direction with respect to the swivel axis 28, the rotational movement of which is transmitted to the swivel shaft via an angular gear 38 so that it can be rotated about the swivel axis 28 together with the cross member 34.

The pallets 18, 20, of which only the pallet 20 pointing towards the viewer is shown in solid lines in the illustration according to FIG. 2, are fastened to support brackets 40 of the cross member 34. The exchangeable pallets 18, 20 have uniform interfaces to the workpiece carrier of the machining center, not shown. In addition to some manufacturer-specific versions, pallets in particular used with standardized interface device, the square or rectangular pallet 18, 20 shown on the clamping side being provided with grid bores or parallel T-slots.

In order to prevent a collision of the pallets 18, 20 during the swiveling movement with the workpiece carrier or with other elements of the machine bed, the pallet changer 16 is provided with a lifting device 42 which the pallets 18, 20 with reference to the workpiece carrier surface or to the base surface of the machine bed or of the cabin floor can be raised in the Y direction.

An H-shaped pallet door 44 is also mounted on the cross member 34, the central partition wall 46 of which extends between the two pallets 18, 20 along the cross member 34. Two circumferential walls 48, 50, which form the H-legs, are arranged transversely to the partition wall 46 and extend in the pallets 18, 20 indicated in FIG. 2 with a rectangular clamping surface at a parallel distance from the side surfaces 52, 54 of the pallets 18, 20. This means that the pallets are encompassed by the adjacent sections of the peripheral walls 48, 50 and by the partition wall 46, so that the section of the pallet 20 pointing towards the viewer and the section of the pallet 18 pointing towards the work spindle remain open.

Fig. 3 shows a schematic plan view of the pallet changer 16 from Fig. 2. It can be seen that the legs 48a, 50a of the workpiece carrier side of the peripheral walls 48, 50 and the partition wall 46 with side walls 56, 58 and a cabin roof, not shown, and the base of the workpiece carrier or a cabin floor to form a closed processing cabin, the peripheral walls of which are shown hatched in the illustration in FIG. 3. On the side edges of the side walls 56, 58 adjacent to the legs 48a, 50a, sealing devices 64, 66, for example labyrinth seals, are arranged which can be brought into sealing contact with the side edges 60, 62 of the legs 48a, 50a, so that the processing chamber in the transition area between the side walls 56, 58 to the pallet door 44 is sealed.

As indicated in FIG. 3, corresponding seals 68 can also be arranged on the horizontally running upper and / or lower edges (parallel to the plane of the drawing in FIG. 3) of the pallet door 44, so that the gaps between the cabin roof or the cabin floor the / workpiece carrier can be sealed. The partition 46 is provided with seals 68 in a corresponding manner.

In the case of a rigid pallet door 44, these seals 68 or, if applicable (in the case of sealless constructions), would grind the corresponding upper / lower edges during the pivoting of the pallet door 44 on the cabin roof or the cabin floor / workpiece carrier, so that the contact surface is subject to excessive wear is exposed. In order to avoid this, the pallet door 44 in the pallet changer 16 shown in FIG. 2 is designed with telescopic contact surfaces. In the indicated embodiment, these telescopic areas of the pallet door 44 are formed by telescopic walls 70, 72, which are arranged overlapping on the peripheral walls 48, 50 or the partition wall 46 and protrude above the respective upper or lower edge, so that the contact surfaces on the Cabin door or on the cabin floor are formed on the telescopic walls 72 and 70, while the end edges of the side walls 48, 50 and the partition wall 46 are arranged at a distance from the contact surfaces are. These all-round telescopic walls 70, 72 can be lifted off the respective contact surface (cabin floor / workpiece carrier, cabin roof) in order to pivot the pallet door 44, so that the cabin door 44 can be freely pivoted. To actuate the telescopic walls 70, 72, these can be connected to the lifting device 42, for example via suitable coupling / deflection devices, so that the lifting movement of the pallets 18, 20 can also be used to actuate the telescopic walls 70, 72. Of course, other telescopic constructions, such as bellows, etc., can also be used to form the contact surfaces of the pallet door 44. It is also possible to form a telescopic wall 70 only in the lower edges of the pallet door 44, while the upper edge remains in contact with the cabin roof during the pivoting movement. To actuate the upper telescopic walls 72, the lifting device 42 can be provided with a deflection device, by means of which the pallet lifting movement is deflected by 180 ° into a wall lowering movement.

When changing the pallet, the workpiece to be machined is clamped on the pallet 20 in the transfer position and the clamping of the pallet 18 in the machining position on the workpiece carrier is released. The lifting device 42 is then actuated so that the pallet 18 is lifted off the workpiece carrier. At the same time, the lifting movement of the lifting device 42 is transmitted to the telescopic walls 70 and - if present - 42 via a coupling, not shown, so that the telescopic walls 70, 72 are moved towards one another and the seals 68 are lifted off the cabin floor / workpiece carrier or from the cabin roof. The cross member is then pivoted through 180 ° by actuating the swivel motor 36, so that the finished machined workpiece clamped on the pallet 18 is brought into the transfer position and the workpiece located on the pallet 20 is brought into the machining position. The relative arrangement of the pallet door 44 with respect to the two pallets 18, 20 is maintained during this pivoting movement.

After swiveling, the pallet 20 is lowered onto the workpiece carrier by actuating lifting device 42 and clamped to the latter. At the same time, the telescopic walls 70, 72 are brought back into their contact position, so that the processing chamber is sealed again. The processing can now take place by suction extraction of the tool chips and / or under an inert gas atmosphere, so that the risk of explosion / ignition is reduced to a minimum.

Since the circumferential walls 48, 50 are arranged at a relatively short distance from the adjacent side surfaces 52, 54 of the pallets 18, 20, the volume of the processing chamber is reduced on both sides by the proportion indicated in dashed lines in FIG that the removal of chips from the processing chamber is significantly simplified due to the minimum volume.

When designing the machine, it is only necessary to ensure that the swivel range indicated in FIG. 3 remains free, so that a collision with peripheral devices or with the operator is impossible.

The area of the pallet door 44 facing away from the workpiece carrier is freely accessible, so that during the Machining of a workpiece, a new workpiece can be clamped on the pallet 20 without hindrance.

4 shows a further exemplary embodiment in which a U-shaped pallet door 80 is used instead of a one-piece, H-shaped pallet door 44. In this embodiment, too, the partition wall 46 is fastened to the cross member, although the peripheral walls are formed by legs 80, 82 which are mounted on the cross member so as to be displaceable transversely to the partition wall 46. The indicated in Fig. 4 shift from the solid position to the dashed position allows that depending on the position of the legs 82, 84 one of the two pallets is encompassed by the peripheral walls, while the other pallet is freely accessible. In the position of the legs 82, 84 shown in FIG. 4, the side edges 86, 88 running perpendicular to the plane of the drawing bear against the sealing devices 64, 66. In order to bring the dashed palette 20 with the workpiece clamped thereon into the machining position, the swivel motor 36 is actuated, so that the partition wall 46 and the two legs 82, 84 are rotated through 180 ° about the swivel axis 28, so that the one shown in FIG 4 hatched area is open downwards. The two legs 82, 84 are then moved on the cross member by a suitable displacement mechanism until they have reached the dashed position and thereby grip the pallet 20. When the pallet door 44 is pivoted, the side edges 90, 92 then bear against the sealing devices 62, 64, so that again a tight processing chamber is formed.

The variant described in FIG. 4 has the advantage over the previously described embodiment that only one half of the peripheral walls 48, 50 must be formed with the corresponding sealing devices, so that the weight to be pivoted is reduced and the number of seals to be installed is reduced.

Instead of the exemplary embodiments shown in FIGS. 2 and 4 with flat peripheral walls 48, 50 and 82, 84, it is also possible to design pallet doors with curved peripheral walls in order to adapt the geometry of the processing chamber to the geometry of the pallet used.

Disclosed is a pallet door for a pallet swivel changer, in which a partition between the processing and loading area (transfer area) for two pallets can be pivoted together with at least one peripheral wall section encompassing the pallets, the peripheral walls and the partition walls being joined together with a workpiece carrier Complement the cabin, at least in sections, to form a closed processing chamber.

Claims

Expectations 1. Pallet changer with at least two pallets (18, 20), each of which can be brought from a transfer position into a processing position by means of a rotary drive (36), in which a pallet (18, 20) can be clamped on a workpiece carrier, at least the one in Pallet (18) of the pallet changer (16) located in the processing position is surrounded by a peripheral wall (48, 50; 82, 84) and a partition (46) is arranged between the pallets (18, 20), which is located together with a cabin surrounding the tool carrier (56, 58) to form a processing chamber, characterized in that at least one section of the peripheral wall (48, 50; 82, 84) adjacent to the partition (46) can be pivoted with the partition (46). 2. Pallet changer according to claim 1, characterized in that the partition (46) and the two peripheral walls (82, 84) together form a U-shaped pallet door (44). 3. Pallet changer according to claim 2, characterized in that the two peripheral walls forming the U-leg (82, 84) are displaceable along its longitudinal axis from one side to the other side of the partition (46). 4. Pallet changer according to claim 1, characterized in that the peripheral walls (48, 50) and the partition (46) together form an H-shaped pallet door (44) and each have a pallet (18, 20) within one through the partition (46 ) and two peripheral wall sections (48a, 50a) of defined space is arranged. 5. Pallet changer according to claim 4, characterized in that the peripheral walls (48, 50) and the partition (46) are integrally formed. 6. Pallet changer according to one of the preceding claims, characterized by a lifting device (42) through which the peripheral walls (48, 50; 82, 84) and the partition (46) can be lifted off the cabin floor or the cabin roof. 7. Pallet changer according to claim 6, character- ized in that the walls (46; 48, 50; 82, 84) have telescopic support sections (70) which can be lifted off the workpiece carrier by the lifting device (52). 8. Pallet changer according to claim 7, characterized in that the walls (46; 48, 50; 82, 84) are provided in the contact area to a cabin roof with telescopic sections (72) which can be actuated by an actuating device (42). 9. Pallet changer according to claim 7 or 8, characterized in that seals (68), preferably labyrinth seals, are arranged along the contact edges of the contact sections (70) and / or the sections (72). 10. Pallet changer according to one of the preceding claims, characterized in that the side edges (60, 62; 86, 88; 90, 92) of the peripheral wall sections are designed as sealing edges.