Gripping or clamping device with magnetic position detection

Abstract

In a gripping or clamping device, it is very important to record the position of the clamping jaw. In the prior art, this is achieved by incremental or absolute measurements, such as performing optical scanning of the measurement slope. The invention provides a solution that is more cost-effective and is not susceptible to contamination and also space-saving. It is suggested to attach a magnetic code to at least one clamping jaw and to evaluate it using a magnetic sensor.

Description

Technical Field

[0001] The invention relates to a gripping or clamping device comprising a housing with a clamping guide and at least one clamping jaw movable in the clamping guide, the housing being provided with a position sensor for detecting the position of the at least one clamping jaw. Background Art

[0002] Such a gripping or clamping device is known from DE 102021122975 A1. It is proposed that a measuring bevel is integrated into the clamping jaws, which is scanned by a proximity sensor. The position of the clamping jaws can be detected based on the distance of the proximity sensor from the portion of the measuring bevel that is in its field of view, because the field of view of the sensor slides along the measuring bevel when the clamping jaws move.

[0003] However, this solution has some disadvantages. First, the proximity sensor is an optical sensor and is relatively expensive.

[0004] In addition, a certain distance must be maintained to the reference surface that determines the distance in order to avoid contamination. For this purpose, a spacer sleeve is used, with which the measuring bevel is recorded optically.

[0005] The subject matter of DE 10 2021 121 686 A1 is also less susceptible to contamination, but is relatively more expensive, in which an electric field is generated using a coil which is detuned by the movement of the clamping element and whose detuning is evaluated and the distance is determined therefrom.

[0006] An older method of processing is to record the feed and, starting from the initial position, determine how long it has moved in one direction to determine the position. However, this solution is not precise, so the reference run to the initial position must be performed again and again to obtain the best possible position detection. Summary of the invention

[0007] Based on this prior art, the object of the present invention is to create a gripping or clamping device which is insensitive to contamination, can be purchased inexpensively and enables precise position determination.

[0008] This object is achieved by a gripping or clamping device according to the features of independent claim 1. Useful configurations of such a device can be found in the subsequent dependent claims.

[0009] In this respect, a gripping or clamping device is provided, which comprises a housing with a clamping guide and at least one clamping jaw which can be moved in the clamping guide, wherein the housing is provided with a position sensor for detecting the position of the at least one clamping jaw. According to the invention, it is characterized in that at least one clamping jaw is provided with a magnetic coding which has at least the length of the clamping stroke of the at least one clamping jaw and has magnetically coded markings on this length which can be read using a position sensor in the form of a magnetic sensor arranged in the housing.

[0010] In fact, the position is detected by the mutual displacement between the magnetic codings on the gripping jaws, and since the magnetic sensor is installed in the housing, the sensor can be designed to be very space-saving. Although possible, it is not necessary to maintain a large distance between the magnetic coding and the magnetic sensor. When the gripping jaw with the magnetic coding is moved by the magnetic sensor, it detects the change of the coding mark and as part of the signal evaluation, the position of the gripping jaw can be inferred. The signal from the magnetic sensor can be evaluated in the evaluation circuit of the magnetic sensor, on the sensor board or main board of the gripping or clamping device, or in an external control unit connected via the connection on the connection board.

[0011] In a specific embodiment, the magnetic coding can be applied to a plastic strip and the plastic strip can be connected, preferably bonded, to at least one jaw. This makes it possible to use prefabricated magnetically coded plastic strips and keep the costs of producing the position sensor as low as possible. To achieve a defined attachment and damage-free storage, the magnetically coded plastic strip can be applied to a steel strip, which is then attached to at least one jaw.

[0012] In order to ensure a play-free guidance of the clamping jaws in the clamping guide, it makes sense if at least one of the clamping jaws has a recess for receiving the steel strip. A magnetically coded plastic strip cut to length can then be inserted into this recess together with the steel strip, preferably glued on.

[0013] As part of the initial commissioning of the position sensor, after positioning the magnetic encoding, a reference run is performed on at least one of the jaws. When approaching the end position and reaching the end position, the encoding signal detected by the magnetic sensor is read out. In the meantime, in a preferred embodiment, the magnetic encoding can represent an absolute encoding, where each magnetic encoding mark can be uniquely identified by the magnetic sensor in the longitudinal direction of the encoding. This enables the magnetic sensor to determine at a specific point in the encoding how much the jaws are open or at which point the jaws are located.

[0014] Another, but less preferred, solution is an incremental encoding, in which recurring identical marks are arranged in the longitudinal direction of the magnetic encoding. Here, a reference run may be necessary again after decommissioning, since the individual marks can only be counted as they pass by, but each mark cannot be identified individually. Since counting only makes sense from one end position, this incremental encoding is simpler, but also has the disadvantages mentioned.

[0015] It can preferably be provided that the magnetic coding 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. The coding and the magnetic sensor are thus in a defined position relative to one another and the coding is protected from external influences. However, the clamping jaws can be moved unhindered between their end positions. Thus, there is no need for externally applied solutions as in the prior art. On the contrary, this design allows a particularly compact device.

[0016] If the clamping device provides not only one but several clamping jaws, these can also have several magnetic encodings. In the simplest solution, each encoding is assigned its own magnetic sensor. However, in another embodiment, it can also be provided that several adjacent codes are read simultaneously by a common magnetic sensor. This enables a redundant evaluation of several codes, so that in the event of slight deviations, an average value between the positions determined by two codes can be determined.

[0017] However, it is particularly preferred to provide a plurality of jaws which are synchronized with one another due to a mechanical toothing. In this case, the magnetic encoding only needs to be provided on one jaw. If one jaw is driven by a motor, the toothing allows at least one other jaw to be moved towards or away from the workpiece in the opposite direction or substantially in the same way without any path deviations occurring.

[0018] The present invention described above is explained in more detail below using exemplary embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A gripping or clamping device having two opposing jaws is shown in perspective;

[0020] Figure 2 The side cross-sectional view also shows Figure 1 gripping or clamping devices;

[0021] Figure 3 As Figure 2 The longitudinal cross-sectional view shown shows the Figure 2 gripping or clamping device. DETAILED DESCRIPTION

[0022] Figure 1A gripping or clamping device 1 is shown, which can be used, for example, on a robot gripper of a machine tool. The device 1 is surrounded by a housing 2, in which a clamping guide 8 is arranged. In this clamping guide 8, two clamping jaws 9 and 10 are arranged, which can be moved along the clamping guide 8. The clamping guide 8 is formed in the form of a T-shaped undercut groove, which is introduced into the housing 2 from the upper side. Each clamping jaw 9 and 10 is equipped with a half "T" for guidance, which guides pass each other in such a way that the clamping jaws attached to them can be moved flat towards each other. The clamping jaws 9 and 10 are adjusted towards and away from each other by means of an electric motor, which is provided with electrical energy via a connection 5 as well as the introduction of control commands and the transmission of measured values ​​to a control unit.

[0023] like Figure 2 As can be clearly seen in the diagram, the connection 5 is connected to the main board 3 via the connection plate 4, wherein the control commands of the control unit (not shown here) are converted into control commands of the drive 13. The drive 13 actuates the two jaws 9 and 10 via the toothing 11, in such a way that the two jaws inevitably operate synchronously with each other. This means that it is sufficient for only the first jaw 9 to be provided with a magnetic coding 12 in the form of a plastic strip, which is glued to the underside of the first jaw 9, facing the magnetic sensor 7 on the sensor board 6. When the jaw 9 is moved in the direction of the clamping guide 8 by the magnetic sensor 7, the magnetic sensor 7 reads out the magnetic coding 12 and, in the case of absolute coding, the position of the first jaw 9 can be read. Relative to the housing 2, on each individual mark, the toothing 11 also similarly leads to the position of the second jaw 10 for this reason. Figure 3 2 shows again the storage of the magnetic sensor 7 on the sensor board 6 in the housing 2 of the device. The sensor board 6 is arranged eccentrically in the housing 2 so that the magnetic sensor 7 can optimally read the magnetic coding 12 attached only to the first jaw 9.

[0024] What has been described above is a gripping or clamping device which is insensitive to contamination, can be purchased inexpensively and enables precise position determination.

[0025] Reference numerals:

[0026] 1 Gripping or clamping device

[0027] 2 Housing

[0028] 3 Motherboard

[0029] 4 Connecting plate

[0030] 5 Connectors

[0031] 6 Sensor Board

[0032] 7 Magnetic sensor

[0033] 8 Clamping guide

[0034] 9 First gripper

[0035] 10 Second gripper

[0036] 11. Tooth

[0037] 12 Magnetic Encoding

[0038] 13 Driver

Claims

1. A gripping or clamping device comprising a housing (2) with a clamping guide (8) and at least one clamping jaw (9, 10) movable in the clamping guide (8), the housing (2) being provided with a position sensor for detecting the position of the at least one clamping jaw (9, 10), It is characterized in that The at least one clamping jaw (9, 10) is provided with a magnetic code (12), which has at least the length of the clamping stroke of the at least one clamping jaw (9, 10) and has a magnetic code mark on the length, which can be read by a position sensor in the form of a magnetic sensor (7) mounted on the housing (2).

2. The gripping or clamping device according to claim 1, characterized in that The magnetic coding (12) is applied to a plastic strip and the plastic strip is connected, preferably glued, to the at least one clamping jaw (9, 10).

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

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

5. A gripping or clamping device according to any one of the preceding claims, characterised in that The magnetic code (12) represents an absolute code, wherein each magnetic code mark can be uniquely identified by a magnetic sensor (7) in the longitudinal direction of the code (12).

6. A gripping or clamping device according to any one of claims 1 to 4, characterized in that The magnetic code (12) comprises an incremental code, in which repeated, identical markings are arranged in the longitudinal direction of the magnetic code (12).

7. A gripping or clamping device according to any one of the preceding claims, characterised in that The magnetic encoding (12) is located on the lower side of the at least one clamping jaw (9, 10), and the magnetic sensor (7) is located below the clamping guide (8) and arranged opposite to the at least one clamping jaw (9, 10).

8. A gripping or clamping device according to any one of the preceding claims, characterised in that A plurality of clamping jaws (9, 10) are provided and have a plurality of magnetic encodings (12).

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

10. A gripping or clamping device according to any one of claims 1 to 7, characterised in that A plurality of clamping jaws (9, 10) are provided which are synchronized with one another by means of a mechanical toothing (11) and which have a magnetic coding (12) on only one of the clamping jaws (9, 10).

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