JPH0373401B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotating clamping device having at least one clamping element for clamping a workpiece and a clamping detector for detecting the clamping force.

Rotating clamping devices with a plurality of clamping elements of the type described above are known, in which each clamping element is provided with a clamping force detector in the vicinity of the workpiece clamping surface. With this clamping force detector, the forces occurring between the clamping device and the workpiece are detected, displayed and, if necessary, used for adjustment purposes to adapt the required clamping force to the requirements in the individual case.

In another known configuration of a rotating clamping device of the first-mentioned type with a basic pawl and an exchangeable temporary pawl,
The mounting screw between the base pawl and the temporary pawl is designed as a strain screw and is designed to become a clamping force detector by attaching the extension measuring strip.

In both of these known configurations, it is not practical, if not entirely impossible, to derive the relatively small measured values detected by the clamping element from the rotating clamping device to an external stationary display or measuring device. The drawback is that it is difficult to use. Disadvantages arise, in particular, because the temporary jaws have to be constructed in such a way that they can be radially offset relative to the basic jaws of the clamping element in order to adapt to different diameters of the workpiece. If you shift or replace the temporary nails like this,
There is a risk of damage to the electrical connection elements required to transmit the measured values from the clamping force detector through the chuck body to the stationary device.

Another disadvantage of the known arrangement is that the effective force is measured on moving parts, which not only requires flexible conductors or sliding transmission of the measured values, but also requires high loads on the transmission device, especially in rotating clamping devices. Due to the presence of the affected components, it is unavoidable that the measurements are subject to influences resulting from frictional forces and wear.

The object on which the invention is based is to provide a clamping force detector in a rotating clamping device in a manner suitable and practical for crude everyday use, while avoiding difficulties in transmitting the measured values. On the other hand, it is necessary to eliminate influences that cause errors in the generation of measured values.

The solution to this problem according to the invention is characterized in that a clamping force detector is provided at the location of the tick body that is subject to deformation due to the clamping force.

With this proposal of the invention, the measurement of the effective force, which causes the above-mentioned difficulties, is no longer carried out, but instead the reaction deformation of the chuck body is measured and used as a measure of the clamping force and the centrifugal force occurring in the clamping device. This not only eliminates the influence of wear and friction on the measured values, but also avoids the problems that exist in known arrangements with respect to the transmission of the measured values and the mounting of the clamping force detector. In the arrangement according to the invention, sufficient space is available for the protected mounting of the clamping force detector. Furthermore, the conductors for transmitting the measured values are fixedly installed and reliably protected, for example by plastic casting.

In a preferred embodiment of the invention, the clamping force detector, which is formed by an elongation measuring strip, is provided on a connecting piece that connects adjacent chuck body sectors to one another at the radially inner end of the pawl guide. At this point on the chuck body, a load is generated which spreads the chuck body due to clamping forces and centrifugal forces, and is particularly well suited for detecting forces.

In a further development of the invention, a clamping force detector formed by a stretch measuring strip is provided on the radially inner edge of the rear chuck guide surface of the chuck body. These elongation measuring strips, which are arranged in the rear end region of the hole through which the chuck piston passes and/or in the plane of the rear chuck guide, are able to detect particularly well the loads on the chuck body resulting from clamping forces and centrifugal forces. .

The drawings show two embodiments of the invention.

In both embodiments, a rotating clamping device is shown as a power-operated three-jaw chuck, the chuck body 1 of which has three clamping jaws guided in a radially movable manner. Each clamping pawl consists of a basic pawl 2 and a temporary pawl 3, which temporary pawl 3 is mounted on the basic pawl 2 in such a way that it can be replaced and displaced in the radial direction. For clarity, the temporary claws 3 are omitted in the front view of FIG. In both configurations, the connection between the basic claw 2 and the temporary claw 3 takes place via teeth. The separation point between the basic claw 2 and the temporary claw 3 is indicated by a chain line. The claw mounting screws required for installation are not shown.

For displacing the base pawl 2, which is guided radially in the chuck body 1, in both embodiments a chuck piston 4 is used, which is guided axially displaceably in a central bore of the chuck body 1. The axial movement of the chuck piston 4 is effected by a power actuator, not shown in the drawings, which is connected to the chuck piston 4 by a pull rod, also not shown. 2 and 3 show a tension screw 5 by means of which the chuck piston 4 is connected to a tension rod (not shown). The front end of the center hole of the chuck body 1 is closed by a lid 6.

The conversion from an axial movement of the chuck piston 4 to a radial movement of the base pawl 2 takes place in both embodiments by means of a so-called wedge pawl transmission. This transmission device includes a wedge pawl formed at the radially inner end of the base pawl 2, which wedge pawl fits into a corresponding wedge recess in the chuck piston 4. Since such wedge transmissions are known in various configurations, further explanation is omitted here.

For example, when clamping a workpiece from the outside between the temporary jaws 3, when the chuck piston 4 is pulled to the left in the first embodiment according to FIG. The load is applied so that it spreads out. In the embodiment according to FIGS. 1 and 2, the pawl guide 7 of the basic pawl 2
does not extend to the small diameter extension of the central hole of the chuck body 1. This pawl guide 7 terminates in a connecting piece 8 which connects in each case two adjacent sectors 9 of the chuck body 1 between the pawl guides 7 of the chuck body 1. When the chuck body 1 rotates, these fan-shaped portions 9 exert a centrifugal force as indicated by the arrow in FIG.
Receive Fc. The influence of this centrifugal force Fc on the chuck and therefore the clamping force is seen in the connecting piece 8 of the chuck body 1 like an elongation stress.

In the embodiment according to FIGS. 1 and 2, a clamping force detector is provided with at least one extension measuring strip 10, which makes it possible to determine the effective clamping force and the centrifugal force due to the reaction forces. The deformation occurring in the chuck body 1 is measured.
Since the elongation measuring strip 10 is arranged on a part of the chuck body 1 and therefore has no relative movement, the disadvantageous effects of friction and kinetic play are eliminated. Furthermore, the conductors 11 necessary for transmitting the measured values are installed with appropriate protection. These conductors 11 are shown schematically in the drawing.

In the second embodiment according to FIG.
It is provided on the radially inner edge of 3. In this embodiment, an elongation measuring strip 1 is provided in the recess of the rear pawl guide surface 13 and in the wall 14 of the hole for the chuck piston 4.
2 is shown.

Even if at least one elongation measuring strip 12 is provided as shown in FIG.
2 is used to measure reaction deformation caused by clamping force and centrifugal force. When subjected to a load due to tightening force and/or centrifugal force, the radial side edges of the rear pawl guide surface 13 also expand and receive stress.
The elongation measuring strip 12 supplies measured values, with which the effective clamping force and the centrifugal force can be detected via the reaction force.

With the above-described structure, it is of course possible to detect not only the respective clamping force when clamping the workpiece on the outside, but also the clamping force when clamping the workpiece on the inside. In this case, the chuck body is compressed by the clamping force and expanded by the centrifugal force, which is taken into account during the detection.

[Brief explanation of drawings]

Fig. 1 is a front view of the first embodiment of the three-pronged chuck, Fig. 2 is a sectional view of the three-pronged chuck taken along the cutting line - in Fig. 1, and Fig. 3 is a front view of the first embodiment of the three-pronged chuck. FIG. 3 is a corresponding cross-sectional view. DESCRIPTION OF SYMBOLS 1...Chuck body, 2...Basic claw, 3...Temporary claw, 8...Connecting piece, 10, 11...Tightening force detector (elongation measurement strip).

Claims (1)

[Claims] 1. In a device having at least one clamping element for clamping a workpiece and a clamping force detector for detecting clamping force, the clamping force detector 10 is installed at a location of the chuck body 1 that is subject to deformation due to the clamping force. Rotating tightening device characterized in that it is provided with 12. 2. The clamping force detector formed by the elongation measuring strip 10 is provided on the connecting piece 8 that connects the sector-shaped portions 9 of adjacent chuck bodies 1 to each other on the radially inner side of the pawl guide 7. A tightening device according to claim 1, wherein: 3. According to claim 1, the clamping force detector formed by the elongation measuring strip 12 is provided on the radially inner edge of the rear chuck guide surface 13 of the chuck body 1. tightening device.