Gripping or clamping device with magnetic position detection part

Abstract

To provide a gripping or clamping device that is resistant to contamination, can be obtained at a low cost and enables accurate position detection.SOLUTION: In a gripping or clamping device 1, it is important to detect the position of clamping jaws 9, 10. In the prior art, this is achieved by incremental or absolute measurements which, for example, carry out optical scanning of a measuring bevel. It is proposed to mount magnetic encoding 12 on at least one clamping jaw and to evaluate this magnetic encoding by use of a magnetic sensor.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a gripping or tightening device which has a casing with a clamping guide and at least one clamping jaw movable in said clamping guide, the casing being assigned a position sensor for detecting the position of the at least one clamping jaw.

[0002] Such a gripping or clamping device is already known from DE 10 2021122975 A1. It is assumed there that the clamping jaws are machined with a measuring bevel which is scanned by means of a proximity sensor. In the course of the sliding of the clamping jaws, the field of view of the sensor slides along the measuring bevel, so that the position of the clamping jaws can be determined depending on the distance of the proximity sensor from the measuring bevel section which is in the field of view of the proximity sensor.

[0003] However, this solution has several disadvantages. Firstly, the proximity sensor is a relatively expensive optical sensor. Furthermore, in order to avoid contamination, a certain distance must be maintained with respect to the reference plane to which the distance is determined. For this purpose, a spacer sleeve is used, through which the optical detection of the measuring slope takes place.

[0004] In DE 10 2021121686 A1, an electric field is generated by a coil, which is detuned by the movement of the clamping element, and the detuning is evaluated and the distance is determined thereby; this prior art subject also has a high resistance to contamination, but is relatively costly.

[0005] Previous methods have been proposed to detect the feed and to determine how far the feed has traveled in one direction from the starting position, thereby determining the position. However, this solution is inaccurate, so that in order to obtain the best possible position detection, a reference run to the starting position must be performed repeatedly.

[0006] Starting from this state of the art, the problem underlying the present invention is to provide a gripping or clamping device which is resistant to contamination, is inexpensive to obtain and allows for precise positioning.

[0007] This problem is solved by a gripping or clamping device having the features of independent claim 1. Advantageous configurations of such a device can be seen from the subsequent dependent claims.

[0008] To that extent, a gripping or clamping device is provided which has a casing with a clamping guide and at least one clamping jaw movable in the clamping guide, the casing being assigned a position sensor for detecting the position of the at least one clamping jaw, the gripping or clamping device being characterized in that, according to the invention, at least one clamping jaw is assigned a magnetic code, which has at least the length of the clamping stroke of the at least one clamping jaw and which carries a magnetically coded marking over this length, which marking can be read by a position sensor in the form of a magnetic sensor assigned to the casing.

[0009] The magnetic detection of the position is achieved by the mutual sliding between the magnetic code on the clamping jaw and the magnetic sensor in the housing, which allows the position sensor to be constructed in a very space-saving manner. It is possible, but not necessary, to maintain a larger distance between the magnetic code and the magnetic sensor. During the movement of the clamping jaw with the magnetic code over the magnetic sensor, the magnetic sensor detects the changing markings on the inside of the code and can deduce the position of the clamping jaw within the scope of the signal evaluation. The evaluation of the signal of the magnetic sensor can take place in an evaluation circuit of the magnetic sensor, on a sensor board or main board of the gripping or clamping device or in an external control unit connected via a connection on a connection board.

[0010] In a specific configuration, the magnetic code can be provided on a plastic band that is connected, preferably glued, to at least one clamping jaw, which allows already pre-manufactured, commercially available magnetically coded plastic bands to be used and keeps the costs for manufacturing the position sensor as low as possible. For defined mounting and damage-free pre-storage, the magnetically coded plastic band can be mounted on a steel strip, which is then attached to at least one clamping jaw.

[0011] In order to ensure play-free guiding of the clamping jaws in the clamping guide, it can be advantageous if at least one clamping jaw has a recess for receiving the steel strip, into which a suitably cut magnetically coded plastic band can be attached together with the steel strip, preferably glued.

[0012] Within the scope of the first start-up of the position sensor, after the positioning of the magnetic code, one reference run of at least one clamping jaw is required, in which case an end position is reached and the signal of the code, detected by the magnetic sensor, is read when the end position is reached. Meanwhile, in a preferred embodiment, the magnetic code is an absolute code, in which each magnetically coded marking is uniquely identifiable by the magnetic sensor in the longitudinal direction of the code. This allows the magnetic sensor to determine how widely opened or in which position the clamping jaw is based on the specific position of the code.

[0013] A less preferred alternative is an incremental code, in which the same markings are set repeated along the length of the magnetic code. In this case, the individual markings are counted only when they pass, but they cannot be individually identified, so that it may be necessary to carry out a new reference run after a shutdown. Since the counting is only valid from the end positions, such incremental codes are simpler but also have the above-mentioned disadvantages.

[0014] It is envisaged that the magnetic code is arranged on the underside of at least one clamping jaw and the magnetic sensor is arranged below the clamping guide opposite the at least one clamping jaw, which has several advantages. The code and the magnetic sensor are thus located in a defined position relative to one another and the code is protected against external influences. The clamping jaws can therefore be moved between the two end positions without hindrance. Outwardly projecting means are therefore not necessary, as in the prior art. Instead, this type of construction allows for a device with a particularly compact construction.

[0015] If the clamping device is provided with not only one clamping jaw but several clamping jaws, these can have several magnetic codes. In this case, in the simplest case, each code is assigned its own magnetic sensor. In another embodiment, however, it can also be provided that adjacent codes are read simultaneously by a common magnetic sensor. This allows a redundant evaluation of the codes, so that in the case of small deviations, a mean value between the positions determined from both codes can be determined.

[0016] However, it is particularly preferred if several clamping jaws are provided and these are synchronized with one another on the basis of mechanical toothing. In this case, only one clamping jaw needs to be provided with one magnetic code. When one clamping jaw is driven by a motor, on the basis of the toothing, at least one other clamping jaw can be moved in the opposite direction or generally in the same way towards or away from the workpiece, without any distance deviations occurring.

[0017] Next, the above-mentioned invention will be described in detail with reference to examples. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a perspective view of a gripping or clamping device with two inverted clamping jaws. [Diagram 2] FIG. 2 is a cross-sectional side view of the gripping or fastening device of FIG. 1; [Diagram 3] 3 shows the gripping or clamping device of FIG. 2 in a longitudinal section as shown in FIG. 2.

[0019] FIG. 1 shows a gripping or clamping device 1, which can be used, for example, in a robot gripper of a machine tool. The device 1 is surrounded by a housing 2, in which a clamping guide 8 is provided, along which two clamping jaws 9 and 10 are provided, which are movable. The clamping guide 8 is formed in the form of a T-shaped undercut groove, which is formed in the housing 2 from the upper side. Each clamping jaw 9 and 10 is assigned a "T" half for a guide, through which the attached clamping fingers pass in mutual contact so that they are movable toward each other in a planar manner. The adjustment of the clamping jaws 9 and 10 in the direction towards and away from each other is performed by an electric motor, which can be supplied with electrical energy via a connection 5 and can also provide operating commands and transmit measured values ​​to a control unit.

[0020] As shown in FIG. 2, the connection part 5 is connected via a connection board 4 to a main board 3, on which the operating commands of a control unit, not shown here, are generated as operating commands to a drive 13. The drive 13 operates both clamping jaws 9 and 10 via the toothing 11, which are thus forced to operate synchronously with one another. It is therefore sufficient for only the first clamping jaw 9 to be assigned a magnetic code 12 in the form of a plastic band glued to the underside of the first clamping jaw 9, facing the magnetic sensor 7 on the sensor board 6. While the clamping jaw 9 is moved in the direction of the clamping guide 8 via the magnetic sensor 7, the magnetic sensor 7 can read the magnetic code 12 and, in the case of an absolute code, at each individual marking, read the position of the first clamping jaw 9 relative to the casing 2, which also results in the position of the second clamping jaw 10 on the basis of the toothing 11. The support of the magnetic sensor 7 on the sensor board 6 inside the casing 2 of the device is again shown in FIG. 3. The sensor board 6 is mounted eccentrically in the casing 2 so that the magnetic sensor 7 can easily read the magnetic code 12 attached to the first clamping jaw 9 only.

[0021] Thus, there has been described above a gripping or fastening device that is resistant to dirt, is inexpensive to obtain and allows for precise location. [Explanation of symbols]

[0022] 1 Gripping or fastening device 2 Casing 3 Main Board 4 Connection board 5 Connection 6 Sensor board 7 Magnetic Sensors 8 Fastening guide 9 First Clamping Jaw 10 Second Clamping Jaw 11 Dentition 12 Magnetic Code 13 Drive unit

Claims

1. A gripping or clamping device, comprising a casing (2) with a clamping guide (8) and at least one clamping jaw (9, 10) movable in said clamping guide (8), said casing (2) being assigned a position sensor for detecting the position of said at least one clamping jaw (9, 10), 1. A gripping or clamping device, characterized in that said at least one clamping jaw (9, 10) is assigned a magnetic code (12), said magnetic code having at least a length of a clamping stroke of said at least one clamping jaw (9, 10) and carrying a magnetically coded marking over said length, said marking being readable by a position sensor in the form of a magnetic sensor (7) assigned to said casing (2).

2. 2. The gripping or clamping device according to claim 1, wherein the magnetic code (12) is provided on a plastic band which is connected, preferably glued, to the at least one clamping jaw (9, 10).

3. 3. The gripping or clamping device according to claim 2, characterized in that the magnetically coded plastic band is provided on a steel strip attached to the at least one clamping jaw (9, 10).

4. 4. A gripping or clamping device according to claim 3, characterized in that said at least one clamping jaw (9, 10) has a recess for receiving said steel strip.

5. 5. A gripping or fastening device according to claim 1, wherein the magnetic code (12) is an absolute code, in which each magnetically coded marking in the longitudinal direction of the code (12) is uniquely identifiable by the magnetic sensor (7).

6. 5. The gripping or fastening device according to claim 1, wherein the magnetic code (12) comprises an incremental code provided with identical markings repeated in the longitudinal direction of the magnetic code (12).

7. 7. The gripping or clamping device according to claim 1, wherein the magnetic code (12) is arranged on the underside of the at least one clamping jaw (9, 10) and the magnetic sensor (7) is arranged below the clamping guide (8) facing the at least one clamping jaw (9, 10).

8. 8. A gripping or clamping device according to claim 1, characterized in that a plurality of clamping jaws (9, 10) are provided, said clamping jaws having a plurality of magnetic codes (12).

9. 9. A gripping or fastening device according to claim 8, characterized in that a number of magnetic codes (12) can be read simultaneously by a common magnetic sensor (7).

10. 8. A gripping or clamping device according to claim 1, characterized in that a plurality of clamping jaws (9, 10) are provided, said clamping jaws being synchronized with one another on the basis of mechanical teeth (11), and only one clamping jaw (9, 10) is provided with one magnetic code (12).

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