Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23B—TURNING; BORING
  • B23B31/00—Chucks; Expansion mandrels; Adaptations thereof for remote control
  • B23B31/02—Chucks
  • B23B31/08—Chucks holding tools yieldably

Definitions

• the invention relates to a tool holder for machine tools with a machine-side and a tool-side holder part and with a coupling device that rotatably connects the holder parts with radial play, which is supported on both sides in the axial direction, and a radially movable clutch disc with at least two radial slots running perpendicular to one another has, in which an axial driver of one holder part engages in the one slot and an axial driver of the other holder part engages in the other slot.
• Such tool holder as for example from DE-AS
• the coupling device which is also known as the Oldham coupling, compensates for any axial misalignment between the tool and the bore to be machined, using the radial play guaranteed by the coupling device between the holder part fastened to the machine tool and the tool receiving holder part. After completion of an operation, the coupling device remains in the setting that this operation has caused. This setting therefore determines the starting point for the next compensation. This can lead to an addition of the corapensation paths. There is therefore a need to start each compensation process from the zero position, i.e. to reset the tool-side holder part to the zero position after completion of an operation.
• a tool holder of a different type which is known from CH-PS 657 297, already provides such a resetting option, using different types of spring devices, some of which are effective via latching elements and thereby greatly reduce the ease of adjustment. Other of these spring devices work radially between the holder parts and, in mutual interaction, define the zero would be. This depends on the preload of the radial spring device and is accordingly inaccurate.
• the invention has for its object to provide a tool holder of the type mentioned, which automatically returns to the zero position, with high precision and without any significant impairment of smoothness.
• each holder part is provided with a conical surface, the conical surfaces lying opposite one another and forming a groove opening in the axial direction, and in that a ring is inserted into the groove is, which rests on each conical surface with a spherical surface and is clamped into the channel by at least one spring.
• the conical surface of the tool-side holder part presses in the direction of movement against the associated spherical surface of the ring, whereupon the ring with its opposite spherical surface on the opposite conical surface of the machine-side holder part migrates in the opening direction of the channel.
• the ring therefore cant in the groove against the force of its spring.
• the spring allows the ring to move back into its axis-perpendicular position, the ring resetting the tool-side holder into the zero position.
• the ring interacting with the conical surfaces defines the zero position with high precision, the accuracy of the restoration being insensitive to asymmetrical spring loading due to the interaction between the ring and the channel.
• the smoothness of the adjustment is at best slightly impaired, since the spring load of the ring to be overcome can be selected so that it is also almost zero in the zero position.
• Low-friction line contact also occurs between the ring and the groove.
• the geometry of the gutter also plays an important role in this context. Particularly advantageous conditions result when the conical surface of the tool-side holder part is inclined more steeply than that of the machine-side holder part. The choice is made so that the deflection movement of the ring is hampered as little as possible and the return movement of the ring is supported as much as possible.
• the smooth running of the coupling device also goes into this optimization process.
• the forces for the compensation movement are transmitted by the tool when it engages in the bore; the resetting must supply the spring loading of the ring.
• the device according to the invention operates under optimal conditions if rollers are provided in the axial direction for supporting the coupling device. These rollers offer practically the same smoothness as balls, but do not have the tendency to press into the respective counter surfaces and thereby lose the original smoothness or even block the coupling device. There is the advantageous possibility of arranging the rollers in recesses of the clutch disc so that the clutch disc works as a roller cage. Depending on the orientation of the rollers (coaxially, radially, in the circumferential direction), different combinations of sliding and / or rolling movements result.
• each compensation and reset movement takes place by rolling the rollers.
• the rollers of each side are preferably arranged in a cage which has at least one radial slot for the passage of the driver of the has associated holder part and is provided with recesses for the rollers, which are aligned parallel to one another and perpendicular to the radial slot.
• one holder part can be elastically braced against the other holder part, whereby the spring force is transmitted with the interposition of a ball bearing .
• the tool holder according to the invention is particularly suitable for the processing of light metal, since this material is damaged if the compensation movements require higher counterforces, as can be easily applied by steel, for example.
• the invention is also advantageously applicable to steel processing.
• the smoothness of the coupling device thus influences the smoothness of the reset device, which in turn minimizes the compensation paths.
• the arrangement of the groove and the ring between the two holder parts can be made as long as the ring is not loaded with the axial forces that occur during machining of the bores.
• a preferred embodiment is characterized in that the channel opens on the tool side and that the spring is supported on the machine-side holder part. This construction is easy to manufacture and assemble.
• At least one of the conical surfaces be carried by a component which is axially adjustable relative to the associated holder part.
• a component which is axially adjustable relative to the associated holder part With such an adjustment option, extremely tight tolerances for an exact insertion of the ring into the channel can be avoided.
• the conical surface of the machine-side holder part is arranged on an annular body which is screwed to the machine-side holder part.
• a coil spring surrounding the tool-side holder part can be used for tensioning. It is advantageous, however, to provide a series of elastic plastic elements which, with a low overall height, ensure uniform tensioning and can be adapted very well to the desired spring characteristics.
• the cross section of the ring must have an inner and an outer convex contour.
• the ring is preferably designed as a toroidal body flattened on both sides in the axial direction. It is easy to manufacture and works very well with the conical surfaces of the channel.
• the ring can be designed as a one-piece circumferential body.
• the ring consists of a plurality of ring segments. These can abut one another in the circumferential direction or can also be distributed at a distance from one another.
• a particularly advantageous arrangement is one in which the ring consists of three relatively short segments, the spacing of which, however, is fixed by interposed spacing elements. Compared to a circumferential ring, this entails advantages in terms of weight and possibly production technology.
• the zero position resetting according to the invention works not only with pure radial compensation, but also equally when the tool holder is able to compensate for angular deviations between the tool and the bore to be machined.
• Figure 1 is an axial section through a tool holder according to the invention.
• FIG. 1 shows the clutch disk used in the device according to FIG. 1;
• 3 shows one of the cages used in the device according to FIG. 1;
• the tool holder according to FIG. 1 has a machine-side holder part 1 which can be inserted into the drive of the machine.
• the holder part 1 is connected to a holder part 2 on the tool side, which serves to hold the tool, in the present case a reamer.
• the holder part 2 can carry out slight radial movements relative to the holder part 1. These radial movements are permitted by a clutch filing 3, which at the same time serves to transmit the axial forces from the holder part 1 to the holder part 2.
• the clutch device 3 comprises above all a clutch disk 4, the shape of which can best be seen in FIG.
• the clutch disc has two pairs of radial slots 5 and 6, which are offset from one another by 90 °.
• a pair of bolts 8 of the machine-side holder part 1 engage in the slots 5, while the slots 6 engage with a pair of bolts 7 of the tool-side holder part.
• the representation of the drivers 7 and 8 in Figure 1 is offset by 90 °.
• Cages 9 are provided on both sides of the clutch disc 4, one of which is shown in FIG. 3. It has four recesses 10 for guiding rollers 11. Furthermore, two pairs of slots 12 and 13 offset from one another by 90 ° are provided. The rollers 11 are aligned parallel to one another, their axes being perpendicular to the radial slots 13. With radial movements in the direction of these slots, the rolling effect of the rollers 11 is effective.
• the two cages 9 are of identical design, but are mounted offset by 90 °. All movements of the coupling device 3 thus take place with the participation of the rollers 11. This results in an extremely smooth adjustment, namely even with the simultaneous transmission of high axial forces. Even in the case of long-term operation, there is no damage to the running surfaces on the clutch disc 4 or the respectively associated holder parts.
• the radial slots 12 in the cages 9 are provided to relieve the weight. In a modified embodiment, they can also be used to engage the opposite pair of entrainers, the cages then being used for torque transmission.
• spring elements 14 - in the present case made of plastic - are provided, which are supported on the machine-side holder part 1 and the tool-side holder part 2 against the Tension holder part 1.
• the spring force is transmitted with the interposition of a ring 15 and a ball bearing 16.
• the ball bearing 16 ensures that the compensation movements are not impeded by the pretension.
• the tool holder In order to cool the reamer, the tool holder is provided with a central coolant guide. Accordingly, the cages 9, like the clutch disk 4, are designed as ring disks.
• FIG. 4 shows a clutch disc 4 for a modified embodiment.
• This clutch disc is also provided with pairs of radial slots 5 and 6 for the engagement of the pairs of drivers 7 and 8, respectively.
• 4 radial recesses 17 are incorporated in the clutch disc, which receive roles, not shown.
• the clutch disc thus serves as a cage for the rollers which act directly between the contact surfaces of the two holder parts 1 and 2. This construction is also characterized by long service lives. Although the rollers perform combined rolling and constant movements, this only slightly reduces the ease of movement. Above all, it remains essentially constant over time.
• All of the rollers can be aligned with their axes parallel to one another. There is also the possibility of align wisely parallel. All roller axes can be radially oriented. However, they can also run in the circumferential direction.
• the coupling device 3 is supported on an abutment
• the tool holder is therefore able not only to carry out radial compensation movements but also to compensate for angular errors.
• the two cone surfaces 20 and 21 define a channel that opens on the tool side. It serves to receive a ring 22 which rests on the conical surfaces 20 and 21 with spherical surfaces 23 and 24. It forms a toroidal body flattened on both sides in the axial direction and is braced by elastic plastic elements 25 into the groove defined by the conical surfaces 20 and 21.
• the plastic elements 25 are supported on the ring body 19 and thus on the machine-side holder part 1.
• the conical surface 21 acts on the ring 22 in the direction of movement and allows the ring 22 with its opposite spherical surface 23 to move along the associated conical surface 20 in the opening direction of the channel.
• the ring thus cant in the groove against the action of the elastic plastic elements 25 on the corresponding side.
• the elastic plastic elements 25 allow the ring 22 to return to its basic position perpendicular to the axis, the tool-side holder part 2 being reset to the zero position.
• the spring force of the elastic plastic elements is selected so that it is just sufficient to reset the smooth-running coupling device.
• the compensation movement is therefore hampered as little as possible.
• the conical surface 21 is aligned steeper than the conical surface 20.
• the choice of Angles and the setting of the spring force form an optimization process in which the smoothness of the coupling device is incorporated and the permissible compensation forces are included.
• the device By turning the ring body 19 relative to the machine-side holder part 1, the device is adjusted so that the ring 22 comes to bear on both conical surfaces 20 and 21.
• a coil spring can be used to clamp the ring into the channel.
• the arrangement of the resetting device can be reversed so that the channel opens towards the machine side.
• the spring elements must then be supported on the tool-side holder part.
• the conical surface arranged on the tool-side holder part adjustable relative to the tool-side holder part in order to ensure the correct contact of the ring. If, on the other hand, one works with sufficiently narrow tolerances, any setting option can be dispensed with entirely.
• the cross-sectional shape of the ring can be chosen as long as it is ensured that the ring can rest against the associated conical surfaces with variable line contact.
• the ring does not have to be formed in one piece, but can consist of a plurality of ring segments which are spaced apart from one another in the circumferential direction.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Details Of Spanners, Wrenches, And Screw Drivers And Accessories (AREA)
• Jigs For Machine Tools (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=6438573

Family Applications (1)

Country Status (2)

Families Citing this family (3)

Citations (5)

Family Cites Families (2)

• 1991
  • 1991-08-20 DE DE19914127325 patent/DE4127325C1/de not_active Expired - Lifetime
• 1992
  • 1992-08-19 WO PCT/EP1992/001894 patent/WO1993003876A1/de active Application Filing

Patent Citations (5)

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