Linear conveyance device and method for manufacturing linear conveyance device

Abstract

A linear conveyance device (1) is provided with: a conveyance path having a stator; a plurality of conveyance bodies that move along the conveyance path; a magnet unit (MA) that is attached to the transport body and generates a magnetic field for position detection; a magnetic detection element (30) that is attached to the conveyance path and detects a magnetic field; a calculation unit (40) that calculates the position of the transport body on the basis of the magnetic field detected by the magnetic detection element; and a correction value storage unit for storing a correction value group, which is a combination of correction values for correcting the position of the transport body, the magnet unit having: magnets (10A) arranged such that different magnetic poles are alternately arranged in the direction of movement of the transport body; and a magnetic shielding part (20A) of the magnet, which is formed of a resin containing a magnet powder, and which is disposed on both end surfaces of the magnet in the moving direction and on the upper surface of the magnet on the opposite side from the facing surface facing the conveyance path, and shields magnetic lines of force from the magnet, the number of the correction value groups being smaller than the number of the conveyance bodies. The calculation unit corrects the position of any one of the transport bodies using a correction value group common to the other transport bodies.

Description

Technical Field

[0001] The present invention relates to a linear conveying device for detecting the position of a movable member and a method for manufacturing the linear conveying device. Background Art

[0002] In a linear conveying device, in order to accurately control the position of a movable member, a position detector detects the position of the movable member based on the magnetism of a magnet disposed in the movable member. In the linear conveying device as described above, if the movable members approach each other, magnetic interference occurs between the magnets, and the accuracy of position detection by the position detector decreases. On top of that, in the linear conveying device, dimensional tolerances and the like during the manufacturing process of the movable member have an influence, and the position detection value of the position detector fluctuates, reducing the accuracy of position detection.

[0003] The position detector described in Patent Document 1 has a magnetic shielding portion at the end and the reverse side in the moving direction of the magnet for position detection provided in the movable member to suppress magnetic interference between the magnets of the approaching movable members.

[0004] Patent Document 1: Japanese Patent No. 7046290 Gazette Summary of the Invention

[0005] However, in the technology of Patent Document 1 described above, it is difficult to accurately form the corner portion of the inner side surface of the magnetic shielding portion where the inner side surface of the reverse magnetic shielding portion provided on the reverse side in the magnetic shielding portion intersects with the inner side surface of the side magnetic shielding portion provided on the side surface and facing the magnet for position detection into a desired shape. That is, in the case of forming the magnetic shielding portion by bending a plate-shaped magnet into a shape covering the reverse side and both side surfaces of the magnet, and in the case of forming the magnetic shielding portion by cutting a block of the magnet into a shape covering the reverse side and both side surfaces of the magnet, it is difficult to form the corner portion into the shape of the magnet with high precision. Therefore, there is a problem that a gap caused by dimensional tolerance is generated between the magnet and the magnetic shielding portion, and the magnetic flux or magnetic force lines are disturbed, reducing the accuracy of position detection.

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to obtain a linear conveying device capable of suppressing a decrease in the accuracy of position detection.

[0007] In order to solve the above problems and achieve the object, the linear conveying device of the present invention has: a conveying path having a stator; a plurality of conveying bodies moving along the conveying path; a magnet part mounted on the conveying body to generate a magnetic field for position detection; and a magnetic detection element mounted on the conveying path to detect the magnetic field. In addition, the linear conveying device of the present invention has: an arithmetic unit that calculates the position of the conveying body based on the magnetic field detected by the magnetic detection element; and a correction value storage unit that stores a combination of correction values for correcting the position of the conveying body, that is, a correction value group. The magnet part has: a magnet configured such that different magnetic poles are alternately arranged along the moving direction of the conveying body; and a magnetic shielding part of the magnet formed by a resin containing magnetic powder and disposed on both end faces in the moving direction of the magnet and on the surface opposite to the surface of the magnet facing the conveying path, that is, the upper surface, to shield the magnetic lines of force from the magnet. The number of the correction value groups is less than the number of the conveying bodies, and the arithmetic unit corrects the position of any one of the conveying bodies using the correction value group common to the other conveying bodies.

[0008] Effects of the Invention

[0009] The linear conveying device according to the present invention has the following effect, that is, it can suppress the reduction in the accuracy of position detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a perspective view showing the structure of the linear conveying device according to Embodiment 1.

[0011] Figure 2 It is a side view showing the structure of the magnet part included in the linear conveying device according to Embodiment 1.

[0012] Figure 3 It is a block diagram showing the structure of the linear conveying device according to Embodiment 1.

[0013] Figure 4 It is a flowchart showing the manufacturing process sequence of the linear conveying device according to Embodiment 1.

[0014] Figure 5 It is a side view showing the structure of the magnet part included in the linear conveying device according to Embodiment 2.

[0015] Figure 6 It is a side view showing the structure of the magnet part included in the linear conveying device according to Embodiment 3. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, the linear conveying device and the manufacturing method of the linear conveying device according to the embodiment of the present invention will be described in detail based on the drawings.

[0017] Embodiment 1

[0018] Figure 1 is a perspective view showing the structure of the linear conveying device according to Embodiment 1. Figure 2 is a side view showing the structure of the magnet portion of the linear conveying device according to Embodiment 1. In Figure 1 and Figure 2 two axes in a plane parallel to the upper surface of the magnet 10A and orthogonal to each other are defined as the X-axis and the Y-axis. In addition, the axis orthogonal to the X-axis and the Y-axis is defined as the Z-axis. For example, the plane (XY plane) parallel to the upper surface of the magnet 10A is a horizontal plane, and the Z-axis direction is the vertical direction.

[0019] The linear conveying device 1 includes a plurality of carriers 2 for conveying an article, a stator 4, a magnetic detection element 30, an arithmetic unit 40, and a servo amplifier 50.

[0020] Each carrier 2 includes a movable member mV that generates a driving magnetic field and a magnet portion MA that generates a position detection magnetic field. The movable member mV and the magnet portion MA are disposed below each carrier 2. In addition, the carrier 2 is an example of a conveying body. If the conveying body has a movable member mV and a magnet portion MA like the carrier 2, it may further have other structural elements.

[0021] In addition, the linear conveying device 1 includes a conveying track 5 provided with the stator 4. In the linear conveying device 1, the carrier 2 is disposed at a position opposite to the conveying track 5. That is, in the linear conveying device 1, the movable member mV is disposed at a position opposite to the stator 4. In the linear conveying device 1, the movable member mV moves on the stator 4, whereby the carrier 2 moves along the conveying direction on the conveying track 5.

[0022] The stator 4 that generates a driving magnetic field and the magnetic detection element 30 that detects the position of the carrier 2 are disposed on the conveying track 5. In the linear conveying device 1, the movable member mV and the stator 4 form a linear motor. The movable member mV and the stator 4 can use an electromagnet for one and an electromagnet or a permanent magnet for the other. In addition, the conveying track 5 is an example of a conveying path. If the conveying path has a stator 4 and a magnetic detection element 30 like the conveying track 5, it may further have other structural elements.

[0023] The magnetic detection element 30 detects the magnetic field (magnetic flux density) of the magnet portion MA. In the linear conveying device 1, the magnet portion MA and the magnetic detection element 30 are position detectors for the linear conveying device. In the linear conveying device 1, the movable member mV and the stator 4 generate a driving magnetic field, and the magnet portion MA generates a position detection magnetic field. In the linear conveying device 1, when the carrier 2 moves along the conveying track 5, the movable member mV moves on the stator 4, whereby the magnet portion MA moves on the magnetic detection element 30.

[0024] In the magnet section MA, magnets (permanent magnets) 10A with different magnetic poles alternately arranged and a magnetic shielding section 20A for shielding magnetic lines of force from the magnets 10A are provided. The magnets 10A are arranged along the moving direction of the movable member mV (the conveying direction of the carrier 2).

[0025] The orientations of the magnetic fields of the magnets 10A are alternately different along the moving direction of the carrier 2. That is, in the magnets 10A, multiple magnetic poles are formed in one magnet along the moving direction of the carrier 2. In addition, multiple magnets may also be arranged along the moving direction, thereby constituting the magnets 10A. The magnets 10A are formed in a rectangular parallelepiped shape. In Figure 2 , one of the side surfaces of the rectangular parallelepiped magnet 10A is shown. The magnets 10A are arranged on the carrier 2 such that the direction in which multiple magnetic poles are arranged is aligned with the moving direction of the carrier 2.

[0026] In Figure 2 , the solid arrow 7 shows the magnetic field generated by the magnets 10A. In addition, in Figure 2 , the white arrow 11 inside the magnets 10A shows the orientation of the magnetic field inside the magnets 10A.

[0027] The magnetic shielding section 20A includes: side magnetic shielding sections provided on both end faces in the moving direction of the magnets 10A (the front surface and the rear surface in the traveling direction); and an upper surface magnetic shielding section arranged on the surface opposite to the surface of the magnets 10A that faces the conveying track 5, i.e., the upper surface. The perpendiculars from the front surface and the rear surface in the moving direction of the magnet section MA to the moving direction are parallel to the moving direction.

[0028] The end faces of the magnets 10A on which the side magnetic shielding sections are arranged are the front surface and the rear surface of the magnets 10A. The surface of the magnets 10A on which the upper surface magnetic shielding section is arranged is the upper surface opposite to the surface that faces the conveying track 5. According to this structure, when viewed from the Y-axis direction, the magnetic shielding section 20A is formed by connecting the side magnetic shielding sections and the upper surface magnetic shielding section, and has a shape that covers both end faces and the upper surface of the magnets 10A.

[0029] In addition, when viewed from the conveying track 5, it can be said that the upper surface of the magnets 10A in close contact with the upper surface magnetic shielding section is the reverse side (back surface) of the magnets 10A. In addition, when viewed from the conveying track 5, the inner wall surface of the upper surface magnetic shielding section in close contact with the magnets 10A can be said to be the bottom surface of the magnetic shielding section 20A.

[0030] Of the outer wall surfaces of the rectangular parallelepiped magnet 10A, the surfaces parallel to the YZ plane are the two side surfaces of the magnet 10A, that is, the front surface and the rear surface in the moving direction. Of the outer wall surfaces of the rectangular parallelepiped magnet 10A, the surfaces parallel to the XY plane are the upper surface and the bottom surface of the magnet 10A. In addition, of the outer wall surfaces of the rectangular parallelepiped magnet 10A, the surfaces parallel to the XZ plane are the other two side surfaces of the magnet 10A.

[0031] In Figure 1 the side surface magnetic shielding portion is in close contact with the magnet 10A through the end surface parallel to the YZ plane, and the upper surface magnetic shielding portion is in close contact with the magnet 10A through the upper surface parallel to the XY plane. The side surface magnetic shielding portion covers the two end surfaces (front surface and rear surface) of the magnet 10A parallel to the YZ plane, and the upper surface magnetic shielding portion covers the surface (upper surface) of the magnet 10A parallel to the XY plane.

[0032] The front surface, the rear surface, and the upper surface among the outer wall surfaces of the rectangular parallelepiped magnet 10A are in close contact with the inner wall surface of the magnetic shielding portion 20A. That is, the corner portions formed by the upper surface and the front surface of the magnet 10A and the corner portions formed by the upper surface and the rear surface of the magnet 10A are covered by the inner wall surface of the magnetic shielding portion 20A. In addition, the corner portions formed by the upper surface and the front surface of the magnet 10A and the corner portions formed by the upper surface and the rear surface of the magnet 10A are the corner portions on the upper surface side of the magnet 10A. As described above, in the linear conveying device 1, the corner portions of the inner wall surface of the magnetic shielding portion 20A that contact the corner portions on the upper surface side of the magnet 10A are in close contact with the corner portions on the upper surface side of the magnet 10A, and there is no gap between the magnetic shielding portion 20A and the magnet 10A. In addition, the inner wall surface of the magnetic shielding portion 20A can cover the other two side surfaces of the rectangular parallelepiped magnet 10A other than the front surface and the rear surface.

[0033] The magnetic shielding portion 20A is formed of a material having a magnetic permeability exceeding 1, such as iron. Specifically, the magnetic shielding portion 20A is formed of a resin containing magnetic powder. In Embodiment 1, the magnetic shielding portion 20A of the shielding portion having magnetism and the magnet 10A are integrally formed, and the magnetic shielding portion 20A is in close contact with the magnet 10A without a gap. According to this structure, the magnetic shielding portion 20A and the magnet 10A are fixed and held to each other. That is, the magnetic shielding portion 20A fixes and holds the magnet 10A, and the magnet 10A fixes and holds the magnetic shielding portion 20A.

[0034] In the integral molding of Embodiment 1, for example, a mold for the magnet 10A is first used, and the magnet 10A is formed by injection molding. That is, the magnetic material flows into the mold for the magnet 10A to form the magnet 10A. Then, the magnet 10A enters the mold for the magnetic material resin (for the magnetic shielding portion 20A), and the magnetic material resin flows into the mold for the magnetic material resin. The mold for the magnetic material resin has a cavity in the portion where the magnetic shielding portion 20A is to be formed and the portion for the magnet 10A to enter. The magnet 10A enters the portion for the magnet 10A to enter among this cavity portion, and the magnetic material resin flows into the portion where the magnetic shielding portion 20A is to be formed. Thus, the magnetic shielding portion 20A is integrally molded with respect to the magnet 10A.

[0035] In addition, in the integral molding of Embodiment 1, the magnetic shielding portion 20A can be formed first. In this case, a mold for the magnetic shielding portion 20A is first used, and the magnetic shielding portion 20A is formed by injection molding. That is, the magnetic material resin flows into the mold for the magnetic material resin to form the magnetic shielding portion 20A. Then, the magnetic shielding portion 20A enters the mold for the magnet 10A, and the magnetic material flows into the mold for the magnet 10A. The mold for the magnet 10A has a cavity in the portion where the magnet 10A is to be formed and the portion for the magnetic shielding portion 20A to enter. The magnetic shielding portion 20A enters the portion for the magnetic shielding portion 20A to enter among this cavity portion, and the magnetic material flows into the portion where the magnet 10A is to be formed. Thus, the magnet 10A is integrally molded with respect to the magnetic shielding portion 20A.

[0036] When the magnet 10A is formed prior to the magnetic shielding portion 20A, the mold for the magnet 10A is the first mold, and the mold for the magnetic shielding portion 20A is the second mold. In addition, when the magnetic shielding portion 20A is formed prior to the magnet 10A, the mold for the magnetic shielding portion 20A is the first mold, and the mold for the magnet 10A is the second mold.

[0037] The magnetic detection element 30 detects the magnetic field generated by the magnet 10A. Specifically, the magnetic detection element 30 converts the displacement amount of the magnetic field generated by the magnet 10A into a change in the signal output. An example of the magnetic detection element 30 is a Hall element. The magnetic detection element 30 sends the detected magnetic field to the arithmetic unit 40. A plurality of magnetic detection elements 30 are installed on the conveying track 5 side along the moving direction of the magnet portion MA. As the magnet portion MA moves, the magnetic field detected by each magnetic detection element 30 changes.

[0038] Based on the detection value of the magnetic flux (magnetic flux density, etc.) sent from the magnetic detection element 30, the arithmetic unit 40 calculates the position (position data) of the carrier 2 (magnet portion MA). The position of the carrier 2 corresponds to the position of the magnet 10A and the position of the movable member mV. The arithmetic unit 40 sends the position data of the carrier 2 to the servo amplifier 50.

[0039] Figure 3 is a block diagram showing the structure of the linear conveying device according to Embodiment 1. The linear conveying device 1 has a plurality of carriers 2-1 to 2-n (n is a natural number greater than or equal to 2). The carriers 2-1 to 2-n are the same carriers as the carrier 2 described in Figure 2 . In Embodiment 1, when there is no need to distinguish the carriers 2-1 to 2-n, the carriers 2-1 to 2-n are sometimes referred to as the carrier 2. Each of the carriers 2-1 to 2-n has a magnet 10A with the same shape and a magnetic shielding portion 20A with the same shape (not shown in Figure 3 ).

[0040] In the linear conveying device 1, the carriers 2-1 to 2-n move along the conveying track 5. When the carriers 2-1 to 2-n pass over the magnetic detection element 30, the magnetic detection element 30 detects the magnetic field generated by the magnet 10A possessed by the carriers 2-1 to 2-n. The magnetic detection element 30 sends the detected magnetic field to the arithmetic unit 40.

[0041] The arithmetic unit 40 has a correction value storage unit 41. The correction value storage unit 41 stores correction values for correcting the positions of the carriers 2-1 to 2-n. The correction values are correction values (error correction values) for detecting the position of the magnet 10A with high precision. In addition, the correction value storage unit 41 may be arranged outside the arithmetic unit 40.

[0042] The correction values for correcting the positions of the carriers 2-1 to 2-n may be correction values (signal correction values) for correcting the signal of the magnetic flux density, or correction values (position correction values) for correcting the positions of the carriers 2-1 to 2-n calculated based on the signal of the magnetic flux density. Hereinafter, the case where the correction value for correcting the positions of the carriers 2-1 to 2-n is a signal correction value for correcting the signal of the magnetic flux density will be described.

[0043] For example, when the magnetic flux density of each magnet 10A of the carriers 2-1 to 2-n detected by the magnetic detection element 30 is represented by a sine wave signal, the correction values for correcting the amplitude, offset, etc. of the sine wave signal are signal correction values for correcting the positions of the carriers 2-1 to 2-n. The arithmetic unit 40 uses the signal correction values in the correction value storage unit 41 to correct the amplitude, offset, etc. of the sine wave signal. If the magnetic flux density is set as B, the magnetic flux density of each magnet 10A of the carriers 2-1 to 2-n is represented by, for example, B = Psinθ + Q. Here, P is the amplitude and Q is the offset. The offset is the deviation amount of the average value of the signal waveform from the central value 0. The signal correction values are obtained and stored in the correction value storage unit 41 in advance before the linear conveying device 1 leaves the factory.

[0044] The operation unit 40 corrects the signal of the magnetic flux density transmitted from the magnetic detection element 30 by using the signal correction value stored in the correction value storage unit 41. Based on the corrected signal of the magnetic flux density, the operation unit 40 calculates the position data of the carriers 2-1 to 2-n. The operation unit 40 transmits the position data of the carriers 2-1 to 2-n to the servo amplifier 50.

[0045] The signal correction value stored in the correction value storage unit 41 is common among the carriers 2-1 to 2-n. In addition, in the linear conveying device 1, it is sufficient to use a common signal correction value for at least two of the carriers 2-1 to 2-n. That is, the number of groups of the signal correction values (for example, the group of the correction value for amplitude and the correction value for offset) stored in the correction value storage unit 41 may be less than the number of the carriers 2-1 to 2-n. That is, the combination of the correction values, that is, the correction value group, may be less than the number of the carriers 2-1 to 2-n. Hereinafter, the case where the number of the correction value groups is one will be described. In addition, the type of the correction value included in the correction value group may be one type or multiple types.

[0046] The servo amplifier 50 controls the linear motor based on the position data of the carrier 2. Thereby, the power supplied to the stator 4 is adjusted to the power corresponding to the position of the movable member mV. By adjusting the power supplied to the stator 4, the magnitude of the driving magnetic field generated by the movable member mV and the stator 4 is adjusted, and the position of the movable member mV is adjusted. That is, the carrier 2 moves along the conveying track 5.

[0047] In the first embodiment, since the magnetic shielding portion 20A and the magnet 10A are integrally formed, the magnetic shielding portion 20A and the magnet 10A are in close contact without a gap. As described above, in the linear conveying device 1, since there is no gap between the magnetic shielding portion 20A and the magnet 10A, the occurrence of the disorder of the magnetic flux or the magnetic force lines is suppressed. Therefore, the linear conveying device 1 can detect the same sine wave signal for each of the carriers 2-1 to 2-n, and can correct the sine wave signal by using the signal correction value common to each of the carriers 2-1 to 2-n.

[0048] In addition, in the linear conveying device 1, since the magnetic shielding portion 20A and the magnet 10A are integrally formed, it is possible to suppress the manufacturing fluctuations of the shapes of the magnetic shielding portion 20A and the magnet 10A, and it is possible to easily bring the magnetic shielding portion 20A and the magnet 10A into close contact without a gap, and the occurrence of the disorder of the magnetic flux or the magnetic force lines can be suppressed.

[0049] In the case where the carrier 2 that is not the object of position detection is separated from the carrier 2 that is the object of position detection, the magnetic detection element 30 only detects the magnetic field generated by the magnet 10A of the carrier 2 that is the object of position detection, and does not detect the magnetic field generated by the magnet 10A of the carrier 2 that is not the object of position detection.

[0050] In the case where the carrier 2 that is not the object of position detection approaches the carrier 2 that is the object of position detection, if the carrier 2 that is not the object of position detection does not have the magnetic shielding portion 20A, the magnetic detection element 30 will detect the magnetic field generated by the magnet 10A of the carrier 2 that is not the object of position detection. In this case, the position detection accuracy of the carrier 2 is reduced.

[0051] In the linear transfer device 1 of the first embodiment, since the carrier 2 has the magnetic shielding portion 20A, it is possible to suppress the reduction of the position detection accuracy. That is, since the linear transfer device 1 has the magnetic shielding portion 20A, a part of the magnetic force from the magnet 10A of the carrier 2 that is not the object of position detection, which forms a small loop of magnetic lines of force, is shielded by the side magnetic shielding portion and does not reach the magnetic detection element 30. In addition, in the linear transfer device 1, since it has the magnetic shielding portion 20A, a part of the magnetic force from the carrier 2 that is not the object of position detection, which forms a large loop of magnetic lines of force, is shielded by the upper surface magnetic shielding portion and does not reach the magnetic detection element 30.

[0052] In addition, there is a method (hereinafter referred to as method M1) of forming a magnetic shielding portion by bending a plate-shaped magnet. In method M1, when bending the plate-shaped magnet, since a bending R (fillet) caused by manufacturing tolerance is generated at the bending portion, it is impossible to make the magnet closely contact the bending portion of the magnetic shielding portion (in other words, the corner portion of the inner side surface of the magnetic shielding portion that faces the corner portion of the magnet). Therefore, in method M1, there is air between the magnet and the magnetic shielding portion, and the magnetic flux or magnetic lines of force are disordered. As described above, the disorder of the magnetic flux or magnetic lines of force causes fluctuations in the position detection value obtained by the position detector, so the detection accuracy of the position of the carrier is reduced. In addition, in method M1, it is difficult to perform shallow bending processing, so it is necessary to set the dimension in the depth direction of the side magnetic shielding portion to be greater than or equal to a specific value, and it is difficult to achieve thinning.

[0053] In addition, there is a method (hereinafter referred to as Method M2) of forming a magnetic shielding portion by cutting a block of a magnet into a concave shape. In Method M2, due to manufacturing tolerances, the corner of the bottom of the concave portion (in other words, the corner of the inner side surface of the magnetic shielding portion that faces the corner of the magnet) cannot be made a right angle, and an R surface or a C surface is generated at the corner of the bottom of the concave portion. Therefore, the magnet cannot be made to closely contact the corner of the inner side surface of the magnetic shielding portion. Therefore, in Method M2, there is air between the magnet and the magnetic shielding portion, and the magnetic flux or magnetic force lines are disturbed. The disturbance of the magnetic flux or magnetic force lines as described above causes fluctuations in the position detection value obtained by the position detector, and thus the detection accuracy of the position of the carrier is reduced. In addition, since the magnet block is a hard metal compared to aluminum or brass, the processing takes time and is costly.

[0054] As described above, in any of Methods M1 and M2, due to the manufacturing tolerances of the component (magnetic shielding portion), an error in the relative position is generated between the magnet and the magnetic shielding portion, and thus the magnetic field generated by each carrier fluctuates. Therefore, when the carrier manufactured by Methods M1 and M2 is applied to a linear conveying device, in order to suppress the reduction in the detection accuracy of the position of the carrier, it is necessary to calculate the signal correction value for each carrier during the factory test and store it in the correction value storage unit. For example, when the number of carriers mounted on one linear conveying device is 100 (N = 100), it is necessary to store the signal correction values of the magnets of 100 carriers in the correction value storage unit, and a memory with a large capacity is required. In addition, in order to derive the signal correction values of 100 magnets, a long derivation time and a large workload are required, and thus the manufacturing cost of the linear conveying device increases.

[0055] On the other hand, in Embodiment 1, the magnet 10A and the magnetic shielding portion 20A are integrally formed by flowing in a magnetic material and a magnetic material resin, so the magnet 10A is in close contact with the magnetic shielding portion 20A. As a result, there is no air between the magnet 10A and the magnetic shielding portion 20A, and no relative position deviation is generated between the magnet 10A and the magnetic shielding portion 20A. As a result, the magnetic field generated by the magnet portion MA of the linear conveying device 1 does not fluctuate, and the reduction in the detection accuracy of the position of the magnet 10A of the carrier 2 can be suppressed. In addition, in Embodiment 1, the manufacturing tolerance of the magnetic shielding portion 20A can be reduced by accurately manufacturing the resin molding die (die for the magnetic shielding portion 20A) for the magnetic material resin.

[0056] As described above, in Embodiment 1, the fluctuation of the magnetic field generated by the magnets 10A of the N carriers 2 can be suppressed, and the set of signal correction values stored in the correction value storage unit 41 can be one type. Therefore, the storage capacity required for the correction value storage unit 41 is significantly reduced, and the cost of the linear conveying device 1 can be reduced. In addition, the time for deriving the signal correction value can be shortened, and the manufacturing cost of the linear conveying device 1 can be reduced.

[0057] In addition, in Embodiment 1, the magnetic shielding portion 20A is integrally formed with the magnet 10A by a resin containing magnetic powder (resin containing magnetic powder), so that the magnet 10A can be made thinner than in the case of Method M1.

[0058] In addition, in Embodiment 1, the magnetic shielding portion 20A is integrally formed with the magnet 10A by a resin containing magnetic powder, so that the magnetic shielding portion 20A and the magnet 10A can be closely attached without gaps at all surfaces where the magnetic shielding portion 20A and the magnet 10A face each other, including the corners of the inner side surface of the magnetic shielding portion 20A. Thus, in Embodiment 1, compared with the cases of Methods M1 and M2, the position detection accuracy of the magnet 10A can be improved, and low cost due to shortening of the processing time can be achieved.

[0059] In addition, in the case of a rotation angle detection device that detects the rotation angle of a motor shaft (rotating body), the magnet and the rotation angle sensor are in a one-to-one relationship. Therefore, only one set of signal correction values for correcting the position of the magnet is required. In contrast, there are multiple (N) carriers 2 having a movable member mV in the linear conveying device 1, so the position detection magnet 10A and the magnetic detection element 30 are in an N (N≥2) -to-one relationship. That is, there are N magnets 10A whose positions are detected by one magnetic detection element 30. Therefore, when the manufacturing fluctuations of the magnet 10A and the magnetic shielding portion 20A are large, N correction values need to be stored in the correction value storage unit 41. In Embodiment 1, since the manufacturing fluctuations of the magnet 10A and the magnetic shielding portion 20A are small, only one correction value needs to be stored in the correction value storage unit 41.

[0060] As described above, in Embodiment 1, the magnetic shielding portion 20A is integrally formed with the magnet 10A by a resin containing magnetic powder, so the individual fluctuations in the size of the magnetic shielding portion 20A and the positional relationship of the magnetic shielding portion 20A with respect to the magnet 10A are reduced. Thereby, the fluctuations in the shape accuracy for each magnet portion MA can be suppressed, and the linear conveying device 1 can achieve high-precision positioning with one type of correction value.

[0061] Next, the manufacturing process sequence of the linear conveying device 1 will be described. Figure 4This is a flowchart showing the manufacturing process sequence of the linear conveying device according to Embodiment 1. The linear conveying device 1 of Embodiment 1 integrally forms the magnet 10A and the magnetic shielding portion 20A (step S10). N pieces of the integrally formed magnet 10A and magnetic shielding portion 20A are manufactured. Carriers 2-1 to 2-n including the integrally formed magnet 10A and magnetic shielding portion 20A are manufactured.

[0062] For the N carriers 2-1 to 2-n, a set of correction values (such as signal correction values, position correction values, etc.) are calculated. The calculated correction values are stored in the correction value storage unit 41 of the linear conveying device 1 (step S20).

[0063] In addition, when manufacturing M (M is a natural number greater than or equal to 2) linear conveying devices 1, M×N pieces of the integrally formed magnet 10A and magnetic shielding portion 20A are manufactured. Moreover, for the M×N carriers 2, one correction value is calculated. The calculated correction values are stored in the correction value storage unit 41 of each linear conveying device 1.

[0064] As described above, the linear conveying device 1 of Embodiment 1 integrally forms the magnetic shielding portion 20A and the magnet 10A, and the number of combinations (correction value groups) of correction values for correcting the positions of the carriers 2 is less than the number of carriers 2. Moreover, the linear conveying device 1 corrects the positions of the carriers 2 by using a correction value group common to other carriers 2 for any of the carriers 2. Thereby, the linear conveying device 1 can easily suppress the reduction in the accuracy of position detection.

[0065] Embodiment 2.

[0066] Next, use Figure 5 to describe Embodiment 2. In Embodiment 2, a taper is provided on the magnet.

[0067] Figure 5 This is a side view showing the structure of the magnet portion of the linear conveying device according to Embodiment 2. Among the respective structural elements of Figure 5 the structural elements that achieve the same functions as those of the linear conveying device 1 of Embodiment 1 shown in Figure 2 are labeled with the same reference numerals, and repeated descriptions are omitted.

[0068] The linear conveying device 1 of Embodiment 2 has a magnet portion MB instead of the magnet portion MA compared with the linear conveying device 1 of Embodiment 1. The linear conveying device 1 of Embodiment 2 has a magnet portion MB in each of the plurality of carriers 2, but Figure 5 only one magnet portion MB is shown in the figure.

[0069] The magnet section MB has a magnet 10B and a magnetic shielding section 20B. In the magnet section MB, the magnetic shielding section 20B is also integrally formed with the magnet 10B, and the magnetic shielding section 20B is in close contact with the magnet 10B. Similar to the first embodiment, the magnet 10B has a facing surface opposite to the conveying track 5, an upper surface on the side opposite to the facing surface, and two other side surfaces other than the two end surfaces in the moving direction.

[0070] When the magnet 10B of the magnet section MB is viewed from the Y-axis direction, the two end surfaces 61 and 62 in the moving direction (the moving direction of the carrier 2) of the magnet section MB form an inclined conical shape. Due to the conical shape, the width in the X-axis direction (the width in the moving direction) of the magnet 10B gradually becomes smaller from the upper surface side of the magnet 10B toward the facing surface side of the magnet 10B. That is, the width of the magnet 10B gradually tapers from the positive Z direction toward the negative Z direction. The cone angle (taper ratio) of the magnet 10B is the cone angle that can obtain a desired magnetic flux density waveform.

[0071] When the magnetic shielding section 20B of the magnet section MB is viewed from the Y-axis direction, the side magnetic shielding sections arranged at the two end surfaces 61 and 62 in the moving direction of the magnet section MB in the moving direction of the magnet 10B form an inverted conical shape. Due to the inverted conical shape with the inner side surface of the side magnetic shielding section being inclined, the width in the X-axis direction (the width in the moving direction) of the magnetic shielding section 20B gradually becomes larger from the upper surface side of the magnet 10B toward the facing surface side of the magnet 10B. That is, the width of the side magnetic shielding section gradually thickens from the positive Z direction toward the negative Z direction. The inverted cone angle of the magnetic shielding section 20B is the inverted cone angle that can obtain a desired magnetic flux density waveform.

[0072] As described above, the width of the magnet 10B of the magnetic shielding section 20B in the X direction gradually tapers from the upper surface side of the magnet 10B toward the facing surface side of the magnet 10B, and the width of the magnetic shielding section 20B in the X direction gradually thickens from the upper surface side of the magnet 10B toward the facing surface side of the magnet 10B. That is, the upper surface of the magnet 10B becomes larger than the opening of the magnetic shielding section 20B. Moreover, in the magnet section MB, the end surface in the moving direction of the magnet 10B and the inner wall surface in the moving direction of the magnetic shielding section 20B are in close contact. That is, the inverted cone angle of the magnetic shielding section 20B becomes an angle corresponding to the cone angle of the magnet 10B.

[0073] The conical shape in which the width of the magnet 10B gradually narrows from the upper surface side of the magnet 10B toward the facing surface side of the magnet 10B is difficult to achieve by the above methods M1 and M2. That is, in the method M1 of forming the magnetic shielding section by bending a plate-shaped magnet and the method M2 of forming the magnetic shielding section by cutting a block of magnet, it is impossible to make the magnetic shielding section closely adhere to the conical magnet 10B without gaps.

[0074] As described above, in Embodiment 2, the conical magnet 10B and the magnetic shielding portion 20B are integrally formed, so that a structure in which the conical magnet 10B and the inverted conical magnetic shielding portion 20B are in close contact can be realized. In addition, by bringing the conical magnet 10B and the inverted conical magnetic shielding portion 20B into close contact, the magnetic flux density waveform can be adjusted to a desired shape.

[0075] In addition, the magnet portion MB is larger on the opposite side of the magnet 10B than the opening between the side magnetic shielding portions of the magnetic shielding portion 20B on the upper surface of the magnet 10B. Therefore, separation between the magnet 10B and the magnetic shielding portion 20B can be prevented when the magnet portion MB moves at high speed or turns. That is, the conical magnet 10B facing the negative Z direction and the inverted conical magnetic shielding portion 20B facing the negative Z direction are in close contact, so that the magnet portion MB can prevent the magnet 10B from coming off.

[0076] Embodiment 3.

[0077] Next, Figure 6 Embodiment 3 will be described. In Embodiment 3, a taper is provided in the magnetic shielding portion.

[0078] Figure 6 is a side view showing the structure of the magnet portion of the linear conveying device according to Embodiment 3. Among the respective structural elements of Figure 6 the structural elements that achieve the same functions as those of the linear conveying device 1 of Embodiment 1 shown in Figure 2 are denoted by the same reference numerals, and redundant descriptions are omitted.

[0079] The linear conveying device 1 of Embodiment 3 has a magnet portion MC instead of the magnet portion MA as compared with the linear conveying device 1 of Embodiment 1. The linear conveying device 1 of Embodiment 3 has a magnet portion MC in each of the plurality of carriers 2, but Figure 6 only one magnet portion MC is shown in the drawing.

[0080] The magnet portion MC has a magnet 10A and a magnetic shielding portion 20C. In the magnet portion MC, the magnetic shielding portion 20C is also integrally formed with the magnet 10A, and the magnetic shielding portion 20C is in close contact with the magnet 10A.

[0081] When viewed from the Y-axis direction, the side magnetic shielding portions of the magnetic shielding portion 20C of the magnet portion MC are tapered at both end faces in the moving direction of the magnet 10A. Each of the side magnetic shielding portions disposed at both end faces of the magnet 10A faces in the direction from the upper surface side of the magnet 10A toward the opposite side (negative Z-axis direction). The end portion on the opposite side of the inner side surface of the side magnetic shielding portion is longer than the end portion on the opposite side of the outer side surface of the side magnetic shielding portion opposite to the inner side surface. The surface connecting these end portions on the opposite sides of the inner and outer side surfaces is an inclined surface. That is, the front end portions 63 and 64 of the side magnetic shielding portion of the magnetic shielding portion 20C in the negative Z direction have a tapered shape in which the surface on the opposite side of the magnet 10A in the side magnetic shielding portion is inclined, and the width in the X-axis direction (width in the moving direction) gradually decreases from the upper surface side of the magnet 10A toward the opposite side of the magnet 10A. That is, the front end portions 63 and 64 of the side magnetic shielding portion in the negative Z direction gradually become narrower from the positive Z direction toward the negative Z direction. The taper angle of the magnetic shielding portion 20C is a taper angle that can obtain a desired magnetic flux density waveform.

[0082] As described above, regarding the front end portions 63 and 64 of the magnetic shielding portion 20C in the negative Z direction, the width of the magnetic shielding portion 20C in the X direction gradually becomes narrower toward the magnetic detection element 30. The tapered structure in which the width of the front end portions 63 and 64 of the magnetic shielding portion 20C in the negative Z direction gradually becomes narrower toward the magnetic detection element 30 is difficult to achieve in the above methods M1 and M2.

[0083] As described above, in the third embodiment, by bringing the magnet 10A into close contact with the tapered magnetic shielding portion 20C, the magnetic flux density waveform can be adjusted to a desired shape.

[0084] The structures shown in the above embodiments represent an example. They can also be combined with other known techniques, and the embodiments can also be combined with each other. Without departing from the gist, a part of the structure can also be omitted or changed.

[0085] In the above-described Embodiment 1, the linear conveying device 1 was manufactured by integrally forming the magnet 10A and the magnetic shielding portion 20A. However, the magnet 10A and the magnetic shielding portion 20A can also be manufactured by means other than integral molding. For example, in the manufacturing method of the linear conveying device 1, a magnet that becomes the magnet 10A and a magnet that becomes the magnetic shielding portion 20A are precisely cut out with high precision from a block of a single magnet by precision machining such as laser machining. Moreover, in the manufacturing method of the linear conveying device 1, the cut-out magnet is magnetized to form the magnet 10A, and the cut-out magnetic shielding portion 20A and the magnet 10A are assembled to form the magnet portion MA. Then, in the manufacturing method of the linear conveying device 1, the carrier 2 including the magnet portion MA is assembled, and a set of correction values (signal correction values, position correction values, etc.) is calculated for N carriers 2. Moreover, the calculated correction values can be stored in the correction value storage unit 41 of the linear conveying device 1, thereby manufacturing the linear conveying device 1.

[0086] In the linear conveying device 1 manufactured by the manufacturing method as described above, individual fluctuations in the size of the magnetic shielding portion 20A and the positional relationship of the magnetic shielding portion 20A with respect to the magnet 10A are also reduced, and it is possible to suppress the occurrence of disturbances in magnetic flux or magnetic field lines. In addition, fluctuations in the shape accuracy of the magnet portion MA can be suppressed, and the linear conveying device 1 can correct the position of the carrier 2 for any one of the carriers 2 using a correction value set common to the other carriers 2, suppress an increase in the cost of the linear conveying device 1 and the manufacturing cost of the linear conveying device 1, and can easily suppress a decrease in the accuracy of position detection.

[0087] Description of reference numerals

[0088] 1 Linear conveying device, 2, 2-1 to 2-n Carriers, 4 Stator, 5 Conveying track, 10A, 10B Magnets, 20A to 20C Magnetic shielding portions, 30 Magnetic detection element, 40 Arithmetic unit, 41 Correction value storage unit, 50 Servo amplifier, 61, 62 End faces, 63, 64 Front ends, MA to MC Magnet portions, mV Movable member.

Claims

1. A linear conveying device, characterized in that, having: a conveying path having a stator; a plurality of conveyors moving along the conveying path; a magnet part mounted on the conveyor to generate a magnetic field for position detection; a magnetic detection element mounted on the conveying path to detect the magnetic field; an arithmetic unit that calculates the position of the conveyor based on the magnetic field detected by the magnetic detection element; and a correction value storage unit that stores a correction value group which is a combination of correction values for correcting the position of the conveyor, the magnet part having: magnets arranged such that different magnetic poles alternate along the moving direction of the conveyor; and a magnetic shielding part of the magnet formed of a resin containing magnetic powder and disposed on both end faces in the moving direction of the magnet and on the surface opposite to the surface of the magnet facing the conveying path, i.e., the upper surface, to shield magnetic lines of force from the magnet, the number of the correction value groups being less than the number of the conveyors, the arithmetic unit correcting the position for any one of the conveyors using the correction value group common to other conveyors.

2. The linear conveying device according to claim 1, wherein the magnet and the magnetic shielding part are integrally formed.

3. The linear conveying device according to claim 1, wherein the number of the correction value groups is one, the arithmetic unit correcting the position for all of the conveyors using the common correction value group.

4. The linear conveying device according to claim 1 or 2, wherein the corner on the upper surface side of the magnet and the corner of the inner wall surface of the magnetic shielding part that contacts the corner are in close contact.

5. The linear conveying device according to any one of claims 1 to 3, wherein the correction value is a signal correction value for correcting a signal of the magnetic flux density detected by the magnetic detection element.

6. The linear conveying device according to any one of claims 1 to 3, wherein the correction value is a position correction value for correcting the position of the conveyor itself calculated based on the signal of the magnetic flux density detected by the magnetic detection element.

7. The linear conveying device according to claim 2, wherein the magnetic shielding part and the magnet are fixed and held to each other by the integral forming.

8. The linear conveying device according to any one of claims 1 to 6, wherein the magnet has a conical shape in which both end faces in the moving direction are inclined such that the width in the moving direction becomes smaller from the upper surface side toward the opposite surface side, the magnetic shielding part disposed on both end faces of the magnet has an inverted conical shape in which the inner wall surface in the moving direction is inclined such that the width in the moving direction becomes larger from the upper surface side toward the opposite surface side, both end faces of the magnet in the moving direction are in close contact with the inner wall surface of the magnetic shielding part.

9. The linear conveying device according to any one of claims 1 to 6, wherein The magnetic shielding portions disposed on the two end faces of the magnet are such that, in the direction from the upper surface side toward the opposite surface side, the end portion on the opposite surface side of the inner side face in the moving direction is longer than the end portion on the opposite surface side of the outer side face opposite to the inner side face in the moving direction, and the surface connecting the end portions on the opposite surface side of the inner side face and the outer side face is an inclined surface.

10. A manufacturing method of a linear conveying device, which is the manufacturing method of the linear conveying device according to any one of claims 1 to 9, characterized in that, Comprising: A molding step of integrally molding the magnet and the magnetic shielding portion; and A correction value storage step of storing the correction value group in the correction value storage portion.

11. The method for manufacturing a linear conveying device according to claim 10, wherein The molding step includes: A first forming step of forming the magnet by flowing a magnetic material into a first mold; and A second forming step of the magnet entering a second mold and a magnetic material resin flowing relative to the magnet to form the magnetic shielding portion.

12. The method for manufacturing a linear conveying device according to claim 10, wherein The molding step includes: A first forming step of forming the magnetic shielding portion by flowing a magnetic material resin into a first mold; and A second forming step of the magnetic shielding portion entering the second mold and a magnetic material flowing relative to the magnetic shielding portion to form the magnet.

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