DE4307036C1 - Accommodation device for workpieces to be finely machined - Google Patents

Abstract

A cage is arranged in a ball ring (6) which has an outer ring (8) is provided in the floating table (13). The ball ring is angularly movable from the outer ring.The ball ring is connected with the outer ring by a radially arranged bolt (44), whereby the either ring has a groove (46,147) running in the axial plane (vertical plane) of the accommodation cage (3) for the bolt. The bolt, with a tip movement of the ball ring, acts as guide bolt for the ball ring, where the tipping movement is around an orthogonally running axis to the bolt and the groove.

Description

The invention relates to a receiving device for Finely machined workpieces with a holding cage for the workpiece and a receiving cage, in a floating pool table.

Holding devices, in particular for workpieces Finely machined, i.e. honed, lapped or the like machined must be designed so that they are the workpiece hold securely, the workpiece not or only minimally deform and the required degrees of freedom, in which make the workpiece movable.

The present invention relates to a receiving device with four degrees of freedom, d. H. two degrees of freedom for the Displacement movement and two degrees of freedom for the Tilting movement. As cradles with four Degrees of freedom gimbal devices are known at which the receiving cage in which the workpiece is clamped is in the plane and angularly movably mounted. The The workpiece can therefore be vertical in two mutually displaced axes and also by two usually axes perpendicular to each other be pivoted or tilted.  

Such gimbal devices are extreme smooth, what is desired on the one hand, on the other hand however has the disadvantage that the whole Device when machining the workpiece for instability tends, especially when machining the workpiece with a single tool such devices for Tend to swing up. This is especially dangerous given when the workpiece is asymmetrical and large off-axis mass parts having. Such occur during the fine machining Instabilities, then this will Machining result adversely affected because the Swinging movements lead to out-of-roundness.

A cardanic device also has the disadvantage on that a tilting motion that is not in either of the two Tilt axes run, always one out of two around these two Tilting axis is compound tilting movement. Likewise a sliding movement that is not in one direction of the two displacement axes, always one out of two Shifting movements in the direction of the two shifting axes compound movement. Such composite However, movements have the disadvantage that they are associated with a increased friction is connected, which is particularly in the Area of transition from static to sliding friction and the associated risk of swinging up, noticeable. Finally, such gimbals Devices on a large size, so that Processing machines accordingly with a large free space must be provided on the workpiece side.

DE 29 03 622 A1 discloses a receiving device for Workpieces, the workpieces in workpiece plates are used and via a spring-loaded lever be tightened. The individual workpiece mounting plates are individually movable on all sides, so  floating. The workpieces therefore have the tool has two degrees of freedom. Further degrees of freedom are due to an articulated mounting of the honing tool created a work spindle. So this points Workpiece two degrees of freedom and the tool two more Degrees of freedom.

A tensioning device is known from the DD 2 83 100 A5 which has a swimming table on which one Ball holder is provided. In this shot is a ball rotatably supported, with a ball on the ball Workpiece holder is seated. This known tensioning device therefore has two degrees of freedom in the swimming table and two Degrees of freedom in the ball holder with ball on. When disadvantageously, it has been found that the structure this jig builds extremely high because the Ball holder is above the clamping table and also the workpiece holder on the in the ball holder itself located ball sits.

In addition to the large dimensions, this structure also has the decisive disadvantage that the tool high tilting moments in the workpiece and thus in the individual Recordings are initiated. This is less Meaning when the workpiece is grinding is subjected. However, if the workpiece is to be precision machined become, d. H. lapped, honed or machined then it is imperative that such Tipping moments can be avoided.

In addition to the tilting moments, honing also occurs Axial forces in both axial directions of the honing tool, which are added in addition to the torques and have to be supported. Would be familiar with this A rotating honing tool in the clamping device Hole of the workpiece inserted, then the  Ball admission next to the one transferred to the ball Torque also a downward or upward Take up axial force.

A tensioning device is known from DE 32 27 924 C2 with the workpieces to be machined can be. The workpiece is on a Floating plate placed, the floating plate in one Workpiece holder is arranged clamped. The Floating plate can move across balls and axially Held steadfast in the direction. The workpiece holder forms So a swimming table that has two degrees of freedom. Additional degrees of freedom are elastic compliant drive rod of the honing tool created. These degrees of freedom are therefore not at the Pick-up device for the workpiece, but on the tool created yourself.

Although this device is quite suitable, the workpiece to move exactly under the tool, but it can Do not perform a swivel movement of the workpiece so that the Coaxial axis of the workpiece to be machined can be aligned to the axis of the tool. Furthermore does not allow such a recording device Damping of those exerted by the tool on the workpiece Swinging movements.

These problems are solved by the invention characteristic features of the main claim solved.

In the receiving device according to the invention Holding cage for the workpiece in a spherical cap, arranged in particular in a spherical ring. Because the calotte angularly movably received by an outer ring which the workpiece is not in the swim table just be aligned exactly in one plane, but it  can also pivot the axis of the hole to be machined become. So you are no longer elastic flexible honing tool instructed.

In addition, the calotte and the outer ring have the advantage that with an axial movement of the machining tool in Work the calotte in one direction of the outer ring is pressed and clamped there so that it due to the increased friction or the clamping effect maintains the set angular position. This will take effect a swinging of the receiving cage during the Machining process suppressed or damped. As soon as that Machining tool in the axial direction of movement Workpiece changes, the clamp is released and the calotte can in the outer ring up to the plant on the reorienting the opposite contact surface and will then held clamped again.

An advantageous embodiment for limiting the Cradle on two degrees of freedom provides that the spherical cap is arranged radially in particular Bolt is connected to the outer ring, the calotte and / or the outer ring one in the axial plane of the Has receiving cage extending groove for the bolt. Through this bolt, which is either in the calotte or in the Outer ring can be set, a rotation of the Dome in the outer ring around the central axis prevented. On the This becomes the bolt from the machining tool to the workpiece acting torque absorbed and supported.

The center of curvature of the calotte is preferably located within. The dome can be used as a spherical cutout or be designed as a point-symmetrical spherical ring. This Design has the advantage that both when entering, same support forces when extending the tool to rule.  

In a preferred embodiment, that the area of the workpiece to be machined in the area the center of curvature of the calotte. Because with this Embodiment the tool through the center of the Kalotte grips, the swinging of the Suppressed workpiece and the workpiece or The workpiece axis can be adjusted by small movements Cradle aligned coaxially to the tool axis become.

In another embodiment it is provided that the area of the workpiece to be machined is a distance from the Center of the calotte, especially above the Center is located. In this embodiment, the Advantage achieved that high adjustment forces to align the Workpiece with respect to the tool axis can be generated, so that frictional forces within the cradle play a subordinate role. The high adjustment moments of the Tool on the workpiece also contribute to a short Processing time at.

In a preferred embodiment, the workpiece Can be inserted into the calotte via a holding device. At this embodiment is the calotte in Outer ring moves, the outer ring on the swimming table is set. In other embodiments, the Be calotte fixed on the swimming table so that the  Outer ring the workpiece via a suitable holding device records.

The swimming table is advantageously hydrostatic in the Table storage stored. This can cause the frictional forces be reduced to a minimum, taking over the pressure of the between the swimming table and the table bed itself located medium the damping is adjustable. At very a correspondingly high damping is achieved at high pressure, whereas at extremely low pressure the liquid film between the swimming table and the table storage to zero can be dismantled so that the swimming table due its weight rests on the table bed and thereby the frictional force increases.

In a further development it is provided that the swimming table is associated with a decrease in torque. This The decrease in torque is usually on the swimming table opposite side of the outer ring with spherical cap arranged. This decrease in torque will Torque supported over the middle, so none Secondary forces arise that deflect the workpiece on one side would. The torque decrease is about two each. the axis of the cradle each other opposite pins with the swim table and one Frame connected to the cradle, the pins lie in radially arranged elongated holes. Are preferred  the pins with an angle of 90 ° to each other arranged. The elongated holes are cruciform trained torque decrease provided. Through this Design can be done via the two on the swimming table arranged pins on a torque of the swimming table the torque decrease and from this over the two am Frame of the cradle arranged pins on the Frame to be transferred. The swimming table is over the Decreased torque prevented from twisting, however over the elongated holes unhindered in the plane in everyone Direction.

Preferably, the pressure medium for the Workpiece lubrication required. As a result, two separate lubricants or Pressure medium circuits are dispensed with, and it is only one pump required.

In a further training it is provided that the Cradle is arranged on a docking pallet, the docking range of dockable lubricant Has feed openings through which the lubricant Floating table and the workpiece can be fed. It can Lubricant through a bypass line to the receiving cage and from there the area of the workpiece to be machined be fed. This has the advantage of being under pressure standing lubricant that is in the area to be machined  usually fed to the tip of the tool that the resulting chips are removed immediately.

To avoid the stick-slip effect, the Hard chrome-plated outer surface of the cap and is made of Outer ring made of plastic, especially made of PTFE. This Material pairing has the advantage of very little friction, so that especially in the area lower Adjustment speeds the risk of stick-slip Effect in which frictional vibrations by periodic alternating static and sliding friction occur, reduced.

Further advantages and details emerge from the following description, in which with reference to the Drawing a particularly preferred embodiment in individual is shown. Show:

Figure 1 shows a longitudinal section through an embodiment of the receiving device according to the invention with the workpiece inserted.

FIG. 2 shows a plan view of the receiving device according to FIG. 1;

FIG. 3 shows a section III-III according to FIG. 1, showing a decrease in torque;

FIG. 4 shows a section IV-IV according to FIG. 1, showing the table bearing for the swimming table;

FIG. 5 shows a section VV according to FIG. 1, showing the outer ring inserted in the floating table;

FIG. 6 shows a section VI-VI according to FIG. 1; and

Fig. 7 is a section VII-VII of FIG. 4, showing the lubricant supply to the swimming table.

In the example shown in Fig. 1 a longitudinal section of an embodiment of the invention, overall designated 1 feinstzubearbeitende receiving device for the workpieces 2, the workpiece 2 is shown with a dash-dotted line suggestively. This workpiece 2 is seated in a receiving cage 3 and is clamped without deformation via a suitable clamping device 4 . The receiving cage 3 is seated in a receiving bore 5 of a spherical cap 6 and is secured against rotation by means of a bolt 7 . A pull-out of the receiving cage 3 from the cap 6 is prevented by a locking ring 9 which bears against the lower end face 11 of the cap 6 via a disk 10 . The dome 6 is designed as an inner ring with a spherical outer shape or generally as a point-symmetrical spherical ring and is mounted in an outer ring 8 with a hollow spherical inner shape. The outer ring 8 is in turn inserted into a bore 12 of a swimming table 13 and rests on a shoulder 14 . In this position, the outer ring 8 is secured by a screw 15 which engages over the upper side of the outer ring 8 and is screwed into the upper side of the floating table 13 .

The floating table 13 forming the displacement device has on its circumference a radially projecting collar 16 which engages in a table bearing designated overall by 17 . This table bearing is constructed from an upper part 18 and a lower part 19 , which are connected to one another via connecting screws 21 . The upper part 18 and the lower part 19 form on their radial inside a groove 20 , in which the collar 16 engages. The dimensions of the groove 20 and the collar 16 are chosen so that the collar 16 has a certain amount of play both in the vertical direction and in the horizontal direction.

The lower part 19 of the table bearing 17 is rigidly fixed by screws 22 to a frame 23 , whereas the swimming table 13 is provided on its underside with pins 24 which project beyond the underside of the swimming table 13 . Only one of the pins 24 , two of which are provided, is shown. The other pin is located on the side opposite the central axis 25 of the receiving device 1 .

The pins 24 engage in a torque decrease 26 and are held there in elongated holes 27 , which can be seen more clearly from FIG. 3. The radially outer area of the torque decrease 26 rests on webs 28 (see FIG. 3) of the frame 23 arranged in a star shape. As can be seen from FIG. 1, the torque decrease 26 is slidably mounted horizontally in the lower part 19 of the table bearing 17 . The torque decrease 26 with respect to the pins 24 of the floating table can only move in the direction of the elongated holes 27 (see FIG. 3). 90 ° offset to the elongated holes 27 , further elongated holes 29 are provided in the torque take-off 26 , into which pins 30 engage, which are anchored in the web 28 , that is to say in the frame 23 . The torque decrease 26 can therefore be shifted with respect to the frame 23 in the direction of the elongated holes 29 .

The asymmetrical configuration of the workpiece 2 can be seen in the top view of the holding device 1 according to FIG. 2. The bore to be machined is designated 31 . It is therefore desirable that the axis of the tool (not shown) be coaxial with the central axis 25 of the workpiece 2 and the holding device 1 during machining. In FIG. 2, the chuck 4 is further seen that, press the workpiece 2 via two arms 32, which are spring loaded to a reference surface of the accommodating cage 3. It can also be seen that the frame 23 is designed as a pallet 33 , the pallet 33 having a docking surface 34 and being able to be aligned via a recess 35 .

In the section III-III shown in FIG. 3, lubricant lines 36 can be seen , which connect the lubricant supply openings 37 , which are provided on the underside of the pallet 33 . It can also be seen in FIG. 3 that the lower part 19 of the table bearing 17 is provided with a plurality of vertical bores 38 , via which, as can be seen from FIG. 7, the lubricant is conveyed into the gap between the groove 20 and the collar 16 of the swimming table 13 can be.

The section IV-IV shown in FIG. 4 according to FIG. 1 shows how the lubricant is distributed in the gap formed by the groove 20 and the collar 16 of the swimming table 13 . For this purpose, channels 39 are provided which adjoin the vertical bores 38 and which ensure that the lubricant is distributed with certainty in the entire sickle-shaped gap.

From the section VV shown in FIG. 5 according to FIG. 1 it can be seen how the outer ring 8 is held by means of the screws 15 which are screwed into the top of the swimming table 13 . In addition, the two bolts 7 projecting vertically upwards from the cap 6 can be seen , which engage in the receiving cage 3 and secure it against rotation relative to the cap 6 .

FIG. 6 shows a section VI-VI according to FIG. 1, with the clamping device 4 being indicated by way of which the workpiece is held securely in the holding cage 3 . It can also be seen that lubricant lines 40 are also provided in the receiving cage 3 , via which lubricant is supplied to the receiving opening 41 of the receiving cage 3 under pressure, so that the lubricant can penetrate into the workpiece 2 ( not shown ) from below and remove material removed from the workpiece upwards . The lubricant for the lubricant lines 40 is, for. B. removed from a removal opening 42 shown in Fig. 7 and fed via an elastic hose to a feed opening 43 ( Fig. 6). The elastic hose line (not shown) is so flexible that it does not hinder the angular and sliding movements of the receiving cage 3 .

In Fig. 1, finally, the anti-rotation of the calotte 6 with respect to the outer ring 8 or the floating table 13 can be seen . This protection against rotation is achieved by means of a radially arranged bolt 44 which, as can also be seen from FIG. 5, is mounted in a radial receiving bore 45 of the floating table 13 and extends through the outer ring 8 into the spherical cap 6 . The dome 6 and the outer ring 8 each have a vertical groove 46 , 147 , in which the bolt 44 is supported with play in the vertical direction and in the circumferential direction of the dome 6 or the outer ring 8 without play. Torques introduced into the spherical cap 6 are thus absorbed via the bolt 44 , which is supported both by the outer ring 8 and by the floating table 6 . As already mentioned, the torques are also absorbed by the torque decrease 26 , which is arranged under the floating table 13 , and the torque decrease 26 is supported on the frame 23 or on the pallet 33 .

The mode of operation of the receiving device 1 according to the invention is briefly described below. The aim of the receiving device 1 is to automatically align the axis of the bore 31 to be machined coaxially with the axis of the tool. In the case of a workpiece 2 newly clamped in the holding device 1 , the axis of the bore 31 to be machined is generally offset laterally and also pivoted by a certain angle to the axis of the tool. The axis-parallel adjustment of the bore axis to the tool axis, which is carried out by pivoting, is achieved by rotating the spherical cap 6 in the outer ring 8 . For the coaxial alignment, a superimposed displacement of the bore axis in the direction of the tool axis is required, which is done via the floating table 13 . The adjusting forces for aligning the bore axis are applied by the tool penetrating the bore. In the embodiment shown in FIG. 1, the section 47 to be machined lies above the center 48 of the spherical cap 6 , so that large adjustment moments for the spherical cap 6 can be applied with the tool due to a long lever arm. In another embodiment, not shown, the workpiece 2 can be clamped in the holding device 1 such that the center 48 lies in the section 47 to be machined.

Optimal machining results are achieved in that when the tool is inserted into the bore 31 to be machined, the spherical cap 6 in the outer ring 8 is rotated and at the same time the floating table 13 in the table bearing 17 is displaced such that the axes of the bore to be machined and the tool are coaxial with one another. The rotation of the spherical cap 6 in the outer ring 8 is initially smooth, since the spherical cap 6 is accommodated in the outer ring 8 with little play. If the tool is inserted further into the bore, the cap 6 is pushed down in the outer ring 8 and is wedged in this. The dome 6 can still be pivoted in the outer ring 8 , but larger forces are required for this. In this way, optimal damping of oscillating movements of the receiving cage 3 is achieved.

Because e.g. B. during honing the tool next to the tilting movement back and forth, ie an oscillating movement, the clamping action of the cap 6 in the outer ring 8 is canceled when the tool is pulled out of the bore 31 to be machined and the cap 6 at the other end of the Outer ring 8 moves and jammed there. Between the two clamping positions, where the spherical cap 6 can be freely pivoted in the outer ring 8 , the workpiece axis can be readjusted to the tool axis and is then held again in this new tilting position by the subsequent clamping.

The swimming table 13 rests with its collar 16 on a lubricant cushion in the groove 20 , so that it can also slide in the horizontal plane with little force. Optimal damping can also be set here via the pressure of the supplied lubricant, a higher pressure resulting in higher damping.

As a result, a high stability of the entire receiving device is achieved even when machining asymmetrical workpieces 2 and when using single-bar tools. Through the use of a suitable material combination of calotte 6 and outer ring 8 , for. B. by hard chrome plating of the surface of the cap 6 and by using an outer ring 8 made of PTFE, the stick-slip effect is reduced to a minimum.

Since the same medium is used both for floating the floating table 13 and for lubricating, cooling and flushing the processing area, honing oil can advantageously be used. In addition, no separate lines for the hydraulic area and the lubricant area need to be provided. Finally, the outputs of the hydraulic area and the lubricant area can be brought together again, so that the honing oil can be fed together for reprocessing.

Claims (18)

1. receiving device for workpieces ( 2 ) to be machined with a receiving cage ( 3 ) for the workpiece ( 2 ) and a receiving table ( 3 ) receiving, in a table bearing ( 17 ) floating floating table ( 13 ), characterized in that the receiving cage ( 3 ) is arranged in a spherical cap ( 6 ), in particular in a spherical ring, that an outer ring ( 8 ) is provided for the spherical cap ( 6 ) in the floating table ( 13 ) and that the spherical cap ( 6 ) is angularly movable from the outer ring ( 8 ) is recorded. 2. Receiving device according to claim 1, characterized in that the spherical cap ( 6 ) via a particularly radially arranged bolt ( 44 ) is connected to the outer ring ( 8 ), the spherical cap ( 6 ) and / or the outer ring ( 8 ) one in has the axial plane (vertical plane) of the receiving cage ( 3 ) extending groove ( 46 , 147 ) for the bolt ( 44 ). 3. Receiving device according to claim 2, characterized in that the bolt ( 44 ) during a tilting movement of the spherical cap ( 6 ) about an axis to the bolt ( 44 ) and the groove ( 46 , 147 ) extending orthogonally as a guide bolt for the spherical cap ( 6 ) serves. 4. Recording device according to claim 2 or 3, characterized in that during a tilting movement of the spherical cap ( 6 ) around the bolt axis of the bolt ( 44 ) serves as a pivot axis for the spherical cap ( 6 ). 5. Recording device according to one of the preceding claims, characterized in that the center of curvature or the center ( 48 ) of the curved surface of the spherical cap ( 6 ) lies within this. 6. Receiving device according to one of the preceding claims, characterized in that the region ( 47 ) of the workpiece ( 2 ) to be machined lies in the region of the center of curvature of the spherical cap ( 6 ). 7. Receiving device according to one of claims 1 to 5, characterized in that the area ( 47 ) of the workpiece ( 2 ) to be machined is at a distance from the center ( 48 ) of the spherical cap ( 6 ), in particular above the center ( 48 ). 8. Receiving device according to one of the preceding claims, characterized in that the workpiece ( 2 ) can be used directly or indirectly in the calotte ( 6 ). 9. Recording device according to one of the preceding claims, characterized in that the outer ring ( 8 ) is fixed to the swimming table ( 13 ). 10. Recording device according to one of the preceding claims, characterized in that the floating table ( 13 ) is mounted hydrostatically in the table bearing ( 17 ). 11. Recording device according to one of the preceding claims, characterized in that the floating table ( 13 ) is connected to a torque decrease ( 26 ). 12. Recording device according to claim 11, characterized in that the torque decrease ( 26 ) over two with respect to the normal axis of the swimming table ( 13 ) opposite pins ( 24 , 30 ) with the swimming table ( 13 ) and a frame ( 23 ) Receiving device ( 1 ) is connected, the pins ( 24 , 30 ) in radially arranged elongated holes ( 27 , 29 ). 13. Receiving device according to claim 12, characterized in that the pins ( 24 , 30 ) with an angular pitch of 90 ° with respect to a central axis ( 25 ) are arranged to each other. 14. Recording device according to claim 12 or 13, characterized in that the elongated holes ( 27 , 29 ) are provided in a cruciform torque decrease ( 26 ). 15. Receiving device according to one of claims 10 to 14, characterized in that the pressure medium for the floating table ( 13 ) is the lubricant required for workpiece machining. 16. Receiving device according to one of the preceding claims, characterized in that it is arranged on a docking pallet ( 33 ), the docking pallet ( 33 ) having dockable lubricant supply openings ( 37 ) via which the lubricant can be fed to the floating table ( 13 ). 17. Receiving device according to claim 16, characterized in that the lubricant can be supplied to the receiving cage ( 3 ) and from there the area ( 47 ) of the workpiece ( 2 ) to be machined via a bypass line. 18. Receiving device according to one of the preceding claims, characterized in that the outer surface of the cap ( 6 ) is hard chrome-plated and the outer ring ( 8 ) consists of plastic, in particular of PTFE.