Hollow Encoder Calibration Device

Abstract

To provide a calibration device for a hollow encoder, the calibration device being capable of identifying the center position of the hollow encoder accurately and quickly, thereby enabling improvement of the efficiency of encoder calibration work.SOLUTION: A calibration device for a hollow encoder comprises: a main body board portion comprising a calibration-target cylindrical portion; an advancing / retracting portion which is connected to the main body board portion by a fastening member, and which moves close to and away from the main body board portion by the fastening or loosening of the fastening member and has a reversely tapered portion tapered toward the main body board portion; and an adjustment portion disposed between the advancing / retracting portion and the main body board portion and having a plurality of abutment blocks each of which includes an abutment inner circumferential portion and abuts on the reversely tapered portion, and an abutment outer circumferential portion abutting on the inner surface of cylindrical portion of the calibration-target, upon contact which occurs between the reversely tapered portion and the inner circumferential portion and which is interlocked with the movement of the advancing / retracting portion.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a hollow encoder calibration device, and more particularly to a device for calibrating the eccentricity of the central axis of a hollow encoder. [Background technology]

[0002] Encoders mounted on the drive points of various moving equipment such as industrial robots inevitably develop distortion in their rotating shafts due to the effects of vibration and shock over the course of use. Therefore, periodic inspection and calibration of encoders is required. Without calibration, distortion in the encoder's rotating shaft can accumulate, causing errors in the measurement of movement amounts and potentially hindering accurate operation control of the equipment.

[0003] For example, hollow encoders (see Patent Document 1, etc.) are often installed in recessed locations within equipment. Therefore, when calibrating a hollow encoder, the process of specifying the center position of the encoder, known as centering the encoder, requires a lot of man-hours and effort. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-14404 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in consideration of the above points, and provides a hollow encoder calibration device that accurately and quickly identifies the center position of a hollow encoder when calibrating the encoder, thereby improving the efficiency of the encoder calibration work. [Means for solving the problem]

[0006] That is, the hollow encoder calibration device of the embodiment is characterized by comprising: a main body board portion having a calibration tube portion; an advancing / retreating portion having an inverse tapered portion tapering toward the main body board portion, which is connected to the main body board portion by fastening members and moves toward and away from the main body board portion by tightening or loosening the fastening members; and an adjustment portion having a plurality of abutment blocks arranged between the advancing / retreating portion and the main body board portion, which have an abutment inner peripheral portion that abuts against the inverse tapered portion, and an abutment outer peripheral portion that abuts against the inner surface of the cylindrical portion of the object to be calibrated in response to contact between the inverse tapered portion and the inner peripheral portion in conjunction with the movement of the advancing / retreating portion.

[0007] Furthermore, in the hollow encoder calibration device, the calibration tube portion may be erected on the upper surface of the main body board portion, and the advance / retreat portion may include a fitting portion that slides against the calibration tube portion.

[0008] Furthermore, in the hollow encoder calibration device, the adjustment section may include a binding member that binds the contact blocks together.

[0009] Furthermore, in the hollow encoder calibration device, the binding member may be a ring member made of resin.

[0010] Furthermore, in the hollow encoder calibration device, a guide pin may be provided on the upper surface of the main body plate, and a guide groove portion that comes into contact with the guide pin may be formed on the bottom surface of the abutment block, thereby regulating the direction of movement when the abutment block abuts against the inner surface of the cylindrical portion of the object to be calibrated.

[0011] Furthermore, in the hollow encoder calibration device, the number of guide pins and the number of abutment blocks may be the same.

[0012] Furthermore, in the hollow encoder calibration device, the inverse tapered portion of the advancing / retreating portion may have an inverse truncated cone shape.

[0013] Furthermore, in the hollow encoder calibration device, a flange portion may be provided on the outer periphery of the main body disc portion, protruding in a direction perpendicular to the calibration tube portion. [Effects of the Invention]

[0014] The hollow encoder calibration device of the present invention comprises a main body board portion having a calibration tube portion, an advancing / retreating portion connected to the main body board portion by fastening members and having an inverse tapered portion that tapers toward the main body board portion and moves toward and away from the main body board portion by tightening or loosening the fastening members, and an adjustment portion having a plurality of abutment blocks arranged between the advancing / retreating portion and the main body board portion and having an abutment inner peripheral portion that abuts against the inverse tapered portion, and an abutment outer peripheral portion that abuts against the inner surface of the cylindrical portion of the object to be calibrated in response to contact between the inverse tapered portion and the inner peripheral portion in conjunction with the movement of the advancing / retreating portion.Therefore, the task of identifying the center position of the encoder when calibrating a hollow encoder (hollow encoder) can be performed accurately and quickly, thereby improving the efficiency of the encoder calibration work. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 2 is an exploded perspective view of the hollow encoder calibration device according to the embodiment. [Figure 2] FIG. 10 is a cross-sectional view of the advancing / retreating part of the hollow encoder calibration device in a normal state. [Figure 3] FIG. 10 is a schematic perspective view of the normal state of the advancing and retreating part of the hollow encoder calibration device. [Figure 4] FIG. 10 is a cross-sectional view of the advancing and retreating parts of the hollow encoder calibration device in a close proximity state. [Figure 5] FIG. 10 is a schematic perspective view of the advancing and retreating parts of the hollow encoder calibration device in a close proximity state. [Figure 6] FIG. 10 is a bottom view of an adjustment section made up of a plurality of abutment blocks. [Figure 7] FIG. 10 is a cross-sectional view showing a state during calibration. DETAILED DESCRIPTION OF THE INVENTION

[0016] A device called a hollow encoder is attached to a joint where a servo motor or the like is attached in equipment such as an industrial robot, and is used to detect and control the movement amount (angle) of the joint. In particular, in the case of a hollow encoder, a hollow cylinder with the angular displacement direction being the circumferential direction is installed at the joint of the equipment, and the main body of the encoder (for control) is inserted inside this cylinder to detect the sequential movement amount (angle). Therefore, due to the influence of vibrations, shocks, etc. that occur during the operation of the equipment, it is necessary to calibrate the positional deviation when combining the main body of the encoder with the hollow cylinder.

[0017] The three types of calibration required here are (1) orthogonal error in the elongation direction of the hollow cylinder, (2) parallel error in the cross-sectional direction of the hollow cylinder, and (3) eccentricity error from the center of the circle of the hollow cylinder. The hollow encoder calibration device of the embodiment is a device for calibrating the above three types of errors that occur when attaching the hollow cylinder to the main body of the encoder.

[0018] 1 is an overall perspective view showing the main configuration of an embodiment of a hollow encoder calibration device 1. The hollow encoder calibration device 1 includes a main body board section 10, an advancing / retreating section 20, and an adjustment section 30 arranged between the advancing / retreating section 20 and the main body board section 10.

[0019] The main body board 10 is formed in a disk shape. A calibration tube 11 is provided on the upper surface 15 of the main body board 10, into which a rod-shaped calibration member 55 (orthogonal rod, see Figure 7) is inserted. The calibration tube 11 is located at the center of the disk of the main body board 10. In addition, in the main body board 10 of this embodiment, a disk-shaped step 13 smaller than the upper surface 15 is provided at the top of the upper surface 15, and the calibration tube 11 is provided on the step 13. An insertion hole 12 for inserting (attaching) the calibration member 55 is provided in the calibration tube 11, and the insertion hole 12 penetrates the main body board 10 in the vertical direction. A guide pin 17 is provided in the step 13. A fastening hole 18 is provided in the main body board 10, and a bolt 19 serving as a fastening member is inserted into the fastening hole 18 from the underside 16 of the main body board 10. A flange 14 is provided on the outer periphery 10s (side edge) of the main body board 10.

[0020] A rotation hole (not shown) for a hexagonal wrench or the like is formed in the bolt 19, which is a fastening member. By inserting a hexagonal wrench or the like into the rotation hole and rotating the bolt 19, the bolt 19 can be rotated forward and backward from the outside of the main body board part 10 of the hollow encoder calibration device 1. In this embodiment, four bolts 19 are provided radially at equal positions from the center of the insertion hole 12 of the calibration tube part 11 erected on the main body board part 10.

[0021] The advancing / retreating section 20 has an outer surface 22 with a reverse tapered section 26 that tapers toward the main body disc section 10, and an inner surface 23 with a fitting section 21 that fits loosely into the calibration tube section 11. The reverse tapered section 26 is designed to have a precision that is extremely close to a perfect circle in cross section. Therefore, the reverse tapered section 26 has an inverted truncated cone shape when viewed from the side (see Figure 2, etc., described later).

[0022] The advancing / retreating part 20 is provided with a cylindrical fitting part 21 that slides loosely in the calibration tube part 11 that is erected at the center of the disk of the main body board part 10. Due to the combined relationship between the calibration tube part 11 and the fitting part 21, the vertical movement (sliding) of the advancing / retreating part 20 is restricted by the calibration tube part 11. The advancing / retreating part 20 is connected to the main body board part 10 by a bolt 19 (fastening member).

[0023] The advance / retract part 20 is formed with an advance / retract hole 28 into which the bolt 19 is screwed, and a threaded groove 29 into which the bolt 19 is screwed is carved in the advance / retract hole 28. The advance / retract holes 28 are provided radially at equal positions from the center of the cylindrical fitting part 21. The advance / retract hole 28 of the advance / retract part 20 is formed directly above (on an extension of) the fastening hole 18 of the main body board part 10, and the bolt 19 is inserted straight into it. Then, as the bolt 19 rotates forward or backward, the bolt 19 tightens or loosens relative to the threaded groove 29 of the advance / retract hole 28. As the bolt 19 tightens or loosens due to the screwing of the bolt 19, the advance / retract part 20 moves towards or away from the main body board part 10 in conjunction with the threaded groove 29.

[0024] The adjustment unit 30 is disposed between the advance / retract unit 20 and the main body board unit 10, and is configured in a ring shape by bundling multiple abutment blocks 31 (see Figures 3 and 6, etc., described below). The adjustment unit 30 in this embodiment has four abutment blocks 31, and each abutment block 31 is separable. Bundling (binding) multiple abutment blocks 31 together means concentrating each individual abutment block 31 toward the calibration tube unit 11, which is erected at the center of the disk of the main body board unit 10. Because each of the multiple abutment blocks 31 has the same shape, the ring-shaped binding of the abutment blocks 31 and the movement of each abutment block 31 when it abuts against the advance / retract unit 20 are uniform.

[0025] Each abutment block 31 has an inner circumferential abutment portion 36 (slide surface portion) and an outer circumferential abutment portion 32. The inner circumferential abutment portion 36 abuts against the reverse tapered portion 26. Therefore, the inner circumferential abutment portion 36 has the same inclination angle as the reverse tapered portion 26 and is configured to be inclined in a truncated cone shape. A guide groove portion 37 is formed in the bottom surface portion 34 of each abutment block 31, and the guide groove portion 37 abuts against the guide pin 17.

[0026] In the adjustment unit 30, the bundling member 40 that bundles (ties) the multiple abutment blocks 31 together to form a ring is a resin ring member, and an O-ring, square ring, or the like is preferably used. It must have appropriate elasticity and excellent durability and strain resistance. Specifically, the bundling member 40 is formed from a resin material such as nitrile rubber, fluororubber, silicone rubber, ethylene propylene rubber, or chloroprene rubber. The ring member of the bundling member 40 is embedded in an outer peripheral recess 33 formed in the outer abutment portion 32 of the abutment block 31. In another embodiment, the bundling member 40 may be an elastic body such as a spring.

[0027] Fig. 2 is a cross-sectional view of the advance / retract part 20 of the hollow encoder calibration device 1 in a normal state, and Fig. 3 is a schematic perspective view of the same state. The hollow encoder calibration device 1 is attached to a hollow encoder cylindrical part 51, which serves as the calibration target 50. In the disclosed embodiment, the flange part 14 of the main body board part 10 is closely attached to the opening edge part 54 of the opening 53 of the cylindrical part 51. The flange part 14 protrudes in a direction perpendicular to the calibration tube part 11, and is used for aligning the calibration target 50 in parallel. Also, as can be seen from Fig. 3, although the step part 13 is in contact with the opening 53 of the cylindrical part 51, this state is roughly aligned.

[0028] Each abutment block 31 of the adjustment unit 30 is provided with an abutment outer periphery 32, which can abut against the inner surface 52 of the cylindrical portion 51 of the calibration object 50. However, in Figure 2, the advance / retract unit 20 of the hollow encoder calibration device 1 is in an advanced position (separated state) relative to the main body board portion 10. Therefore, the reverse tapered portion 26 of the advance / retract unit 20 has not sufficiently descended (approached the main body board portion 10) relative to the abutment inner periphery 36 of each abutment block 31 of the adjustment unit 30.

[0029] 3, the contact inner circumferential portion 36 of each contact block 31 is not fully pressed by the downward movement of the reverse tapered portion 26 of the advancing / retreating portion 20 (approaching the main body board portion 10). In this state, the contact blocks 31 are still bound together by the contraction force of the resin elasticity of the binding member 40. Therefore, the contact inner circumferential portion 36 is not in contact with the inner surface portion 52 of the cylindrical portion 51 of the calibration object 50, and the hollow encoder calibration device 1 is in a state before calibration.

[0030] Fig. 4 is a cross-sectional view of the advancing / retreating unit 20 of the hollow encoder calibration device 1 in a close proximity state, and Fig. 5 is a schematic perspective view of the same state. Figs. 4 and 5 illustrate the state during calibration of the hollow encoder calibration device 1. For ease of explanation, components related to calibration have been omitted from the drawings. The advancing / retreating unit 20 has a threaded groove 29 of the advancing / retreating hole 28 that threadably engages with the bolt 19, and therefore the advancing / retreating unit 20 moves to a retracted position (close proximity state) relative to the main body panel unit 10 through the rotation (tightening) of the bolt 19. As shown in Fig. 4, the threaded portion between the bolt 19 and the threaded groove 29 is larger than in Fig. 2.

[0031] 4 and 5, the contact inner circumferential portion 36 of each contact block 31 is fully subjected to the pressing force of the reverse tapered portion 26 of the advancing / retreating portion 20 descending (approaching the main body board portion 10). Therefore, the direction of the pressing force of the advancing / retreating portion 20 descending (approaching the main body board portion 10) is bent at a right angle by the contact between the reverse tapered portion 26 and the contact inner circumferential portion 36, and the contact block 31 starts moving away from the calibration tube portion 11 (in the separation direction) through the contact inner circumferential portion 36.

[0032] In this state, the pressure from the advancing / retreating section 20 exceeds the contraction force of the resin elasticity of the binding member 40, and the contact blocks 31 that were bound together in a ring shape in the adjusting section 30 begin to separate, and eventually, as shown in Figure 5, the contact outer periphery 32 comes into contact with the inner surface 52 of the cylindrical section 51 of the calibration object 50. In particular, the cross section of the reverse tapered section 26 of the advancing / retreating section 20 is a truncated cone shape that is a highly accurate perfect circle, and the contact inner periphery 36 of each contact block 31 of the adjusting section 30 is also finished with enough dimensional precision to come into surface contact with the reverse tapered section 26.

[0033] Therefore, each abutment block 31 of the adjustment unit 30 moves radially in a direction (separation direction) away from the calibration tube portion 11 in precise accordance with the movement (downward in the figure) of the advance / retract unit 20 toward the main body board portion 10. In addition, because the binding member 40 is a ring member such as an O-ring, it acts to contract evenly without bias in any part of the binding member 40. Therefore, when each abutment block 31 moves away from the calibration tube portion 11, the contraction force applied to each abutment block 31 from the abutment outer periphery 32 side is also uniform.

[0034] In other words, the reverse tapered portion 26 of the inverted truncated cone of the advancing / retracting portion 20 can press evenly against all of the contact blocks 31 of the adjusting portion 30 while maintaining its perfectly circular cross section, and moves evenly under pressure in conjunction with the advancing / retracting portion 20. As a result, the position where the inner surface 52 of the cylindrical portion 51 of the calibration object 50 abuts against the outer contact portions 32 of all of the contact blocks 31 is the center of the circle (cross section) of the cylindrical portion 51, and also overlaps with the center of the circle (cross section) of the insertion hole 12 of the calibration tube portion 11 of the main body board portion 10, so that the centers of both axes coincide.

[0035] In addition, as can be seen from the bottom view of the adjustment unit 30 in FIG. 6 , a guide groove 37 is formed on the bottom surface 34 of each abutment block 31. The guide groove 37 extends radially from the center O of the central opening 38 of the adjustment unit 30. The adjustment unit 30 of the hollow encoder calibration device 1 according to this embodiment includes four abutment blocks 31 of the same shape. The main body board 10 also includes four guide pins 17, the number of which is the same for each abutment block. As shown in FIGS. 2 to 5 , the guide groove 37 contacts the guide pin 17 fixed on the main body board 10, i.e., the guide pin 17 fixed to the step 13 on the upper surface 15 of the main body board 10 in this embodiment. Therefore, the movement direction of the abutment block 31 (see the dashed-dotted line notation) moving in the direction of the double arrow in FIG. 6 is restricted when the abutment block 31 abuts against the inner surface 52 of the cylindrical portion 51 of the calibration target 50. The relationship between the guide pins 17 and the guide groove 37 further reduces deviation in the movement direction.

[0036] The cross-sectional view of Fig. 7 shows the state when a hollow encoder is calibrated using the hollow encoder calibration device 1 of the embodiment. The components and operations of the hollow encoder calibration device 1 have been described in detail above with reference to Figs. 1 to 6.

[0037] An opening 53 of a cylindrical portion 51 is exposed from a hollow encoder, which is an object to be calibrated 50. The hollow encoder calibration device 1 is attached to the opening 53. Then, the flange portion 14 of the main body board portion 10 is brought into close contact with the opening edge portion 54 of the opening 53.

[0038] Next, the four bolts 19 are each rotated with a hex wrench, and the advancing / retreating unit 20 is retracted (descended) so as to approach the main body panel unit 10. Then, in conjunction with the retraction of the advancing / retreating unit 20, each abutment block 31 of the adjustment unit 30 moves away from the calibration tube unit 11, and the abutment outer peripheries 32 of all the abutment blocks 31 abut against the inner surface 52 of the cylindrical portion 51 of the calibration object 50. As described above, at this point in time, the central axis of the cylindrical portion 51 of the calibration object 50 and the central axis of the calibration tube portion 11 of the main body panel unit 10 of the hollow encoder calibration device 1 coincide with each other.

[0039] Then, the reference goniometer 56 is attached to a rod-shaped calibration member 55 (orthogonal rod), and is connected by screwing through the threaded portion of the calibration member 55 (orthogonal rod) into the insertion hole 12 of the calibration tube portion 11 of the main body board portion 10. In this manner, the calibration work is performed.

[0040] As can be seen from the series of explanations, in the hollow encoder calibration device of the embodiment, the calibration member (orthogonal rod) connected to the calibration tube of the main body disk is positioned on a straight line, thereby reducing orthogonal error in the elongation direction of the hollow cylinder. The flange of the main body disk is in close contact with the edge of the opening of the calibration target, providing good stability during installation and reducing parallel error in the cross-sectional direction of the hollow cylinder. Furthermore, the abutment block moves evenly in conjunction with the advance / retract movement of the advance / retract section, which has a tapered section shaped like an inverted truncated cone, and abuts against the inner surface of the cylindrical part of the calibration target. This fine-tunes the position of the calibration tube of the main body disk, aligning the central axis of the cylindrical part of the calibration target with the central axis of the calibration tube of the main body disk, thereby reducing eccentricity error with the center of the cylinder. High-precision alignment is possible despite the relatively simple mechanism, achieving efficient encoder calibration. [Explanation of symbols]

[0041] 1 Hollow encoder calibration device 10 Main body panel 11 Calibration barrel 12 Insertion hole 13 Step section 14 Flange 15 Top part 17 Guide pin 18 Fastening holes 19 Fastening members (bolts) 20 Advancement and retreat section 21 Fitting part 22 External part 23 Inner surface 26 Reverse tapered section 28 Advance / retreat hole 29 Threaded groove 30 Adjustment part 31 Abutment block 32 Contact outer periphery 33 Outer periphery recess 34 Bottom part 36 Inner circumference of contact 37 Guide groove 40 Binding member (ring member)

Claims

1. a main body panel portion provided with a calibration tube portion; a retractable portion connected to the main body disk portion by a fastening member, and having a reverse tapered portion tapering toward the main body disk portion, which moves toward and away from the main body disk portion by fastening or loosening the fastening member; an adjustment unit having a plurality of abutment blocks disposed between the advancing / retreating unit and the main body board unit, the abutment blocks including an inner circumferential abutment portion that abuts against the reverse tapered portion, and an outer circumferential abutment portion that abuts against the inner surface of the cylindrical portion of the calibration object upon contact between the inner circumferential abutment portion and the reverse tapered portion in conjunction with the movement of the advancing / retreating unit. A hollow encoder calibration device.

2. the calibration tube portion is provided upright on the upper surface of the main body board portion, The hollow encoder calibration device according to claim 1 , wherein the advancing / retreating portion has a fitting portion that slides on the calibration tube portion.

3. The hollow encoder calibration device according to claim 1 , wherein the adjustment unit includes a binding member that binds the contact blocks together.

4. The hollow encoder calibration device according to claim 3, wherein the binding member is a ring member made of resin.

5. A guide pin is provided on the upper surface of the main body board, a guide groove portion that comes into contact with the guide pin is formed on a bottom surface of the abutment block; The hollow encoder calibration device according to claim 1 , wherein a movement direction of the contact block when the contact block contacts the inner surface of the cylindrical portion of the calibration object is restricted.

6. The hollow encoder calibration device according to claim 5, wherein the number of the guide pins and the number of the abutment blocks are the same.

7. The hollow encoder calibration device according to claim 1 , wherein the inverse tapered portion of the advancing / retreating portion has an inverse truncated cone shape.

8. The hollow encoder calibration device according to claim 1, wherein a flange portion is provided on the outer periphery of the main body disk portion, the flange portion protruding in a direction perpendicular to the calibration tube portion.

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