Linear conveying device and method of manufacturing a linear conveying device

Abstract

The linear conveying device (1) includes: a conveying path having a stator; multiple conveyors moving along the conveying path; a magnet unit (MA) mounted on the conveyors to generate a magnetic field for position detection; a magnetic detection element (30) mounted on the conveying path to detect the magnetic field; a calculation unit (40) to calculate the position of the conveyors based on the magnetic field detected by the magnetic detection element; and a correction value storage unit to store a combination of correction values ​​for correcting the position of the conveyors, i.e., a correction value set. The magnet unit includes: a magnet (10A) configured to have different magnetic poles arranged alternately along the moving direction of the conveyor; and a magnetic shielding part (20A) of the magnet, formed by resin containing magnetic powder, and disposed on the two end faces of the magnet in the moving direction and the upper surface of the magnet opposite to the face opposite to the conveying path to shield the magnetic lines of force from the magnet. The number of correction value sets is less than the number of conveyors. The calculation unit corrects the position of any one of the conveyors using a correction value set common to the other conveyors.

Description

Technical Field

[0001] This invention relates to a linear conveying device for detecting the position of a movable part and a method for manufacturing the linear conveying device. Background Technology

[0002] In linear conveyor systems, position detectors detect the position of movable components based on the magnetism of magnets placed within the components to accurately control their position. In the linear conveyor system described above, if the movable components are close to each other, the magnets interfere with each other magnetically, reducing the accuracy of the position detection by the position detector. Furthermore, in linear conveyor systems, dimensional tolerances during the manufacturing process of the movable components can cause fluctuations in the position detection values, further reducing the accuracy of position detection.

[0003] The position detector described in Patent Document 1 has magnetic shielding portions at the end and the opposite side of the position detection magnet of the movable member in the direction of movement, for suppressing magnetic interference between the magnets of the adjacent movable members.

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

[0005] However, in the technology of Patent Document 1 mentioned above, it is difficult to accurately form the corner of the inner side of the magnetic shielding part, where the inner side of the reverse magnetic shielding part located on the reverse side intersects with the inner side of the side magnetic shielding part located on the side side, and the inner side of the side magnetic shielding part located on the side side, into the desired shape. That is, when the magnetic shielding part is formed by bending a plate-shaped magnet to cover the reverse side and both sides of the magnet, and when the magnetic shielding part is formed by cutting a block of magnet to cover the reverse side and both sides of the magnet, it is difficult to form the corner into the shape of the magnet with high precision. Therefore, there is a problem that a gap caused by dimensional tolerances occurs between the magnet and the magnetic shielding part, the magnetic flux or magnetic lines of force are disturbed, and the accuracy of position detection is reduced.

[0006] The present invention was made in view of the above circumstances, and its object is to provide a linear conveying device capable of suppressing the reduction in the accuracy of position detection.

[0007] To solve the aforementioned problems and achieve the objective, the linear conveying device of the present invention includes: a conveying path having a stator; a plurality of conveyor bodies moving along the conveying path; a magnet unit mounted on the conveyor bodies to generate a magnetic field for position detection; and a magnetic detection element mounted on the conveying path to detect the magnetic field. Furthermore, the linear conveying device of the present invention includes: a calculation unit that calculates the position of the conveyor bodies based on the magnetic field detected by the magnetic detection element; and a correction value storage unit that stores combinations of correction values ​​for correcting the position of the conveyor bodies, i.e., correction value sets. The magnet unit includes: a magnet arranged with different magnetic poles alternately arranged along the moving direction of the conveyor body; and a magnetic shielding part of the magnet formed of resin containing magnetic powder, disposed on both end faces of the magnet in the moving direction and on the upper surface opposite to the face of the magnet opposite to the conveying path, to shield magnetic lines of force from the magnet. The number of correction value sets is less than the number of conveyor bodies, and the calculation unit corrects the position of any one of the conveyor bodies using a correction value set common to the other conveyor bodies.

[0008] The effects of the invention

[0009] The linear conveying device of the present invention has the following effect: it can suppress the reduction in the accuracy of position detection. Attached Figure Description

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

[0011] Figure 2 This is a side view showing the structure of the magnet section of the linear conveying device according to Embodiment 1.

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

[0013] Figure 4 This is a flowchart illustrating the manufacturing process sequence of the linear conveying device involved in Embodiment 1.

[0014] Figure 5 This is a side view showing the structure of the magnet section of the linear conveying device according to Embodiment 2.

[0015] Figure 6 This is a side view showing the structure of the magnet section of the linear conveying device according to Embodiment 3. Detailed Implementation

[0016] The linear conveying device and its manufacturing method according to embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0017] Implementation method 1.

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

[0019] The linear conveyor 1 has multiple carriers 2 for conveying items, a stator 4, a magnetic detection element 30, a computing unit 40, and a servo amplifier 50.

[0020] Each carrier 2 has a movable member mV that generates a driving magnetic field and a magnet MA that generates a position detection magnetic field. The movable member mV and the magnet MA are disposed at the lower part of each carrier 2. Furthermore, the carrier 2 is an example of a transport body. If the transport body has a movable member mV and a magnet MA like the carrier 2, it may also have other structural elements.

[0021] Furthermore, the linear conveying device 1 has a conveying track 5 on which a stator 4 is provided. In the linear conveying device 1, the carrier 2 is positioned opposite to the conveying track 5. That is, in the linear conveying device 1, the movable member mV is positioned opposite to the stator 4. In the linear conveying device 1, the movable member mV moves on the stator 4, thereby causing the carrier 2 to move along the conveying direction on the conveying track 5.

[0022] The conveyor track 5 is equipped with a stator 4 that generates a driving magnetic field and a magnetic detection element 30 that detects the position of the carrier 2. In the linear conveying device 1, the movable element mV and the stator 4 form a linear motor. One of the movable element mV and the stator 4 can be an electromagnet, and the other can be an electromagnet or a permanent magnet. Furthermore, the conveyor track 5 is an example of a conveying path. If the conveying path, like the conveyor track 5, has a stator 4 and a magnetic detection element 30, it can also have other structural elements.

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

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

[0025] The magnetic field of magnet 10A alternates in orientation along the direction of movement of carrier 2. That is, in magnet 10A, multiple magnetic poles are formed in a single magnet along the direction of movement of carrier 2. Furthermore, multiple magnets can be arranged along the direction of movement to constitute magnet 10A. Magnet 10A is formed in a cuboid shape. Figure 2 The figure shows one of the sides of a cuboid magnet 10A. The magnet 10A is arranged on the carrier 2 with its multiple magnetic poles aligned with the direction of movement of the carrier 2.

[0026] exist Figure 2 In the image, arrow 7 (solid line) illustrates the magnetic field generated by magnet 10A. Additionally, in... Figure 2 In the image, the white arrow 11 inside magnet 10A indicates the orientation of the magnetic field inside magnet 10A.

[0027] The magnetic shielding part 20A includes: a side magnetic shielding part, which is disposed on both end faces (front surface and rear surface in the travel direction) of the magnet 10A; and an upper surface magnetic shielding part, which is disposed on the upper surface of the magnet 10A opposite to the opposite face of the conveyor track 5. The perpendicular lines from the front surface and the rear surface of the magnet part MA in the travel direction are parallel to the travel direction.

[0028] The end faces of the magnet 10A, which is configured with a side magnetic shielding portion, are the front and rear surfaces of the magnet 10A. The surface of the magnet 10A, which is configured with a top surface magnetic shielding portion, is the upper surface on the opposite side of the surface opposite to the conveyor track 5. According to this structure, when viewed from the Y-axis direction, the magnetic shielding portion 20A is formed by connecting the side magnetic shielding portion and the top surface magnetic shielding portion, resulting in a shape that covers both end faces and the top surface of the magnet 10A.

[0029] Furthermore, if viewed from the transport track 5, the upper surface of the magnet 10A, which is in close contact with the upper surface magnetic shielding portion, can be considered the reverse side (back side) of the magnet 10A. Additionally, if viewed from the transport track 5, the inner wall surface of the upper surface magnetic shielding portion that is in close contact with the magnet 10A can be considered the bottom surface of the magnetic shielding portion 20A.

[0030] The surfaces of the cuboid magnet 10A that are parallel to the YZ plane are two side surfaces of the magnet 10A; in other words, they are the front and rear surfaces in the direction of movement. The surfaces of the cuboid magnet 10A that are parallel to the XY plane are the top and bottom surfaces of the magnet 10A. Additionally, the surfaces of the cuboid magnet 10A that are parallel to the XZ plane are two other side surfaces of the magnet 10A.

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

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

[0033] The magnetic shielding portion 20A is formed using a material with a magnetic permeability exceeding 1, such as iron. Specifically, the magnetic shielding portion 20A is formed using resin containing magnetic powder. In Embodiment 1, the magnetic shielding portion 20A and the magnet 10A are integrally formed, and the magnetic shielding portion 20A and the magnet 10A are tightly attached without gaps. According to this structure, the magnetic shielding portion 20A and the magnet 10A are fixedly 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, the magnet 10A is first formed by injection molding using a mold for the magnet 10A. That is, magnetic material flows into the mold for the magnet 10A to form the magnet 10A. Furthermore, the magnet 10A enters a mold for 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 forms a cavity between the portion where the magnetic shielding portion 20A is to be formed and the portion where the magnet 10A enters. The magnet 10A enters the portion within this cavity where the magnetic material resin flows into the portion forming the magnetic shielding portion 20A, thereby integrally molding the magnetic shielding portion 20A with respect to the magnet 10A.

[0035] Furthermore, in the integral molding of Embodiment 1, the magnetic shielding portion 20A can be formed first. In this case, the magnetic shielding portion 20A is formed by injection molding using a mold for the magnetic shielding portion 20A. That is, magnetic material resin flows into the mold for the magnetic material resin to form the magnetic shielding portion 20A. Moreover, the magnetic shielding portion 20A enters the mold for the magnet 10A, and magnetic material flows into the mold for the magnet 10A. The mold for the magnet 10A forms a cavity between the portion where the magnet 10A is to be formed and the portion into which the magnetic shielding portion 20A enters. The magnetic shielding portion 20A enters the portion into this cavity, and magnetic material flows into the portion into which the magnet 10A is to be formed, thereby integrally molding the magnet 10A with respect to the magnetic shielding portion 20A.

[0036] When the magnet 10A is formed first compared to the magnetic shielding part 20A, the mold used for the magnet 10A is the first mold, and the mold used for the magnetic shielding part 20A is the second mold. Similarly, when the magnetic shielding part 20A is formed first compared to the magnet 10A, the mold used for the magnetic shielding part 20A is the first mold, and the mold used 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 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. Multiple magnetic detection elements 30 are mounted on the side of the transport track 5 along the moving direction of the magnet part MA. As the magnet part MA moves, the magnetic field detected by each magnetic detection element 30 changes.

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

[0039] Figure 3 This is a block diagram showing the structure of the linear conveying device according to Embodiment 1. The linear conveying device 1 has multiple 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 connected to... Figure 2 The carriers described herein are the same as carrier 2. In Embodiment 1, when there is no need to distinguish between carriers 2-1 to 2-n, carriers 2-1 to 2-n are sometimes referred to as carrier 2. Each carrier 2-1 to 2-n has a magnet 10A of the same shape and a magnetic shielding part 20A of the same shape (in Figure 3 (Not shown in the image).

[0040] In the linear conveying device 1, the carriers 2-1 to 2-n move along the conveying track 5. As 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 magnets 10A on the carriers 2-1 to 2-n. The magnetic detection element 30 then sends the detected magnetic field information to the processing 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 position of the carriers 2-1 to 2-n. These correction values ​​are used to detect the position of the magnet 10A with high precision (error correction values). Alternatively, the correction value storage unit 41 may be disposed outside the arithmetic unit 40.

[0042] The correction value used to correct the position of carriers 2-1 to 2-n can be a correction value used to correct the signal of magnetic flux density (signal correction value), or a correction value used to correct the position of carriers 2-1 to 2-n itself calculated based on the signal of magnetic flux density (position correction value). The following explanation addresses the case where the correction value used to correct the position of carriers 2-1 to 2-n is a signal correction value used to correct the signal of magnetic flux density.

[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 value used to correct the amplitude, offset, etc., of the sine wave signal is a signal correction value used to correct the position of the carriers 2-1 to 2-n. The arithmetic unit 40 uses the signal correction value stored 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 to B, the magnetic flux density of each magnet 10A of the carriers 2-1 to 2-n is represented, for example, by B = Psinθ + Q. Here, P is the amplitude, and Q is the offset. The offset is the deviation of the average value of the signal waveform from the center value 0. The signal correction value is obtained in advance and stored in the correction value storage unit 41 before the linear conveying device 1 leaves the factory.

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

[0045] The signal correction values ​​stored in the correction value storage unit 41 are common to the carriers 2-1 to 2-n. Furthermore, in the linear conveying device 1, it is sufficient to use common signal correction values ​​for at least two of the carriers 2-1 to 2-n. That is, the number of groups of signal correction values ​​stored in the correction value storage unit 41 (e.g., groups of amplitude correction values ​​and groups of offset correction values) need only be less than the number of carriers 2-1 to 2-n. In other words, the number of correction value combinations, i.e., correction value groups, need only be less than the number of carriers 2-1 to 2-n. The case where there is only one correction value group will be described below. Furthermore, the correction value group may contain one type of correction value or multiple types.

[0046] The servo amplifier 50 controls the linear motor based on the position data of the carrier 2. This adjusts the power supplied to the stator 4 to correspond to the position of the movable element mV. By adjusting the power supplied to the stator 4, the magnitude of the driving magnetic field generated by the movable element mV and the stator 4 is adjusted, thereby adjusting the position of the movable element mV. In other words, the carrier 2 moves along the transport track 5.

[0047] In Embodiment 1, the magnetic shielding part 20A and the magnet 10A are integrally formed, so the magnetic shielding part 20A and the magnet 10A are tightly attached without gaps. As described above, in the linear conveying device 1, since there is no gap between the magnetic shielding part 20A and the magnet 10A, the occurrence of magnetic flux disturbance or magnetic field line disturbance is suppressed. Therefore, the linear conveying device 1 can detect the same sinusoidal wave signal for each carrier 2-1 to 2-n, and can correct the sinusoidal wave signal using the signal correction value common to each carrier 2-1 to 2-n.

[0048] Furthermore, in the linear conveying device 1, the magnetic shielding part 20A and the magnet 10A are integrally formed, so manufacturing fluctuations in the shape of the magnetic shielding part 20A and the magnet 10A can be suppressed, and the magnetic shielding part 20A and the magnet 10A can be easily and tightly attached without gaps, thus suppressing the occurrence of magnetic flux disturbances or magnetic field line disturbances.

[0049] When the carrier 2, which is not the object of position detection, is separated from the carrier 2, which 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, which is the object of position detection, and does not detect the magnetic field generated by the magnet 10A of the carrier 2, which is not the object of position detection.

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

[0051] In the linear conveying device 1 of Embodiment 1, since the carrier 2 has a magnetic shielding portion 20A, the reduction in position detection accuracy can be suppressed. That is, because the linear conveying device 1 has a magnetic shielding portion 20A, the portion of the magnetic force from the magnet 10A of the carrier 2 (which is not the object of position detection) that forms a loop with small magnetic field lines is shielded by the side magnetic shielding portion and will not reach the magnetic detection element 30. Furthermore, in the linear conveying device 1, because it has a magnetic shielding portion 20A, the portion of the magnetic force from the carrier 2 (which is not the object of position detection) that forms a loop with large magnetic field lines is shielded by the upper surface magnetic shielding portion and will not reach the magnetic detection element 30.

[0052] Furthermore, there is a method (hereinafter referred to as method M1) for forming a magnetic shield by bending a plate-shaped magnet. In method M1, during the bending process of the plate-shaped magnet, a bend radius (R) caused by manufacturing tolerances is generated at the bend, making it impossible for the magnet to be in close contact with the bend of the magnetic shield (in other words, the corner of the inner surface of the magnetic shield opposite the corner of the magnet). Therefore, in method M1, air exists between the magnet and the magnetic shield, causing disturbances in the magnetic flux or magnetic lines of force. The disturbances in the magnetic flux or magnetic lines of force, as described above, cause fluctuations in the position detection value obtained by the position detector, thus reducing the accuracy of the carrier's position detection. In addition, in method M1, shallow bending is difficult to perform, so the depth dimension of the side magnetic shield needs to be set to a value greater than or equal to a specific value, making it difficult to achieve thinness.

[0053] Additionally, there is a method (hereinafter referred to as method M2) that forms a magnetic shield by machining the block of magnet into a concave shape. In method M2, due to manufacturing tolerances, it is impossible to make the bottom corner of the concave portion (in other words, the corner of the inner surface of the magnetic shield opposite the corner of the magnet) a right angle, resulting in an R-surface or C-surface at the bottom corner of the concave portion. Therefore, it is impossible to make the magnet and the corner of the inner surface of the magnetic shield tightly adhere. Consequently, in method M2, air exists between the magnet and the magnetic shield, causing disturbances in the magnetic flux or magnetic field lines. These disturbances in the magnetic flux or magnetic field lines cause fluctuations in the position detection value obtained by the position detector, thus reducing the accuracy of the carrier's position detection. Furthermore, the magnet block is a harder metal than aluminum or brass, making machining time-consuming and expensive.

[0054] As described above, in either method M1 or M2, manufacturing tolerances of the component (magnetic shielding part) will result in relative positional errors between the magnet and the magnetic shielding part, causing fluctuations in the magnetic field generated by each carrier. Therefore, when carriers manufactured using methods M1 and M2 are applied to a linear conveyor, in order to suppress the reduction in the accuracy of carrier position detection, it is necessary to calculate and store the signal correction value for each carrier in the correction value storage unit during factory testing. For example, if there are 100 carriers (N=100) mounted on one linear conveyor, the signal correction values ​​of the magnets for 100 carriers need to be stored in the correction value storage unit, requiring a large-capacity memory. In addition, exporting the signal correction values ​​of 100 magnets requires a long export time and a large workload, thus increasing the manufacturing cost of the linear conveyor.

[0055] On the other hand, in Embodiment 1, the magnet 10A and the magnetic shielding part 20A are integrally formed by incorporating magnetic material and magnetic material resin, thus the magnet 10A and the magnetic shielding part 20A are in close contact. Therefore, there is no air between the magnet 10A and the magnetic shielding part 20A, and no relative positional deviation occurs between them. Consequently, the magnetic field generated by the linear conveying device 1 at the magnet part MA does not fluctuate, and the reduction in the detection accuracy of the position of the magnet 10A on the carrier 2 can be suppressed. Furthermore, in Embodiment 1, the manufacturing tolerance of the magnetic shielding part 20A can be reduced by manufacturing a high-precision mold for the magnetic material resin, i.e., a resin molding mold (the mold for the magnetic shielding part 20A).

[0056] As described above, in Embodiment 1, the magnetic field generated by the magnets 10A of the N carriers 2 can suppress fluctuations, and the set of signal correction values ​​stored in the correction value storage unit 41 can be only one. Therefore, the storage capacity required by the correction value storage unit 41 is greatly reduced, and the cost of the linear conveying device 1 can be reduced. In addition, the time for deriving the signal correction values ​​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 part 20A is integrally formed with the magnet 10A using a resin containing magnetic powder, so the magnet 10A can be made thinner compared to the case of Method M1.

[0058] Furthermore, in Embodiment 1, the magnetic shielding portion 20A is integrally molded with the magnet 10A using resin containing magnetic powder. This allows the magnetic shielding portion 20A and the magnet 10A to be tightly bonded without gaps at all opposing surfaces, including the corners of the inner side of the magnetic shielding portion 20A. Therefore, in Embodiment 1, compared to methods M1 and M2, the position detection accuracy of the magnet 10A can be improved, and cost reduction due to shorter processing time can be achieved.

[0059] Furthermore, in the case of a rotation angle detection device that detects the rotation angle of the 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 ​​is needed to correct the position of the magnet. In contrast, the linear conveyor 1 has multiple (N) carriers 2 with movable parts mV, so the magnets 10A used for position detection and the magnetic detection elements 30 are in an N (N≥2) to 1 relationship. That is, N magnets 10A are used to detect the position by one magnetic detection element 30. Therefore, if the manufacturing of the magnets 10A and the magnetic shielding part 20A has large fluctuations, N correction values ​​need to be stored in the correction value storage unit 41. In Embodiment 1, since the manufacturing fluctuations of the magnets 10A and the magnetic shielding part 20A are small, only one set of correction values ​​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 using resin containing magnetic powder, thus reducing individual fluctuations in the size of the magnetic shielding portion 20A and its positional relationship relative to the magnet 10A. Consequently, fluctuations in the shape accuracy of each magnet portion MA can be suppressed, and the linear conveying device 1 can achieve high-precision positioning using a single correction value.

[0061] Next, the manufacturing process sequence of the linear conveyor 1 will be explained. Figure 4This is a flowchart illustrating the manufacturing process sequence of the linear conveying device according to Embodiment 1. In Embodiment 1, the linear conveying device 1 integrally molds the magnet 10A and the magnetic shielding part 20A (step S10). N integrally molded magnets 10A and magnetic shielding parts 20A are manufactured. Carriers 2-1 to 2-n, comprising the integrally molded magnets 10A and magnetic shielding parts 20A, are manufactured.

[0062] For N carriers 2-1 to 2-n, a set of correction values ​​(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] Furthermore, when manufacturing M linear conveyor devices 1 (M being a natural number greater than or equal to 2), M×N integrally formed magnets 10A and magnetic shielding parts 20A are produced. Moreover, a set of correction values ​​is calculated for each of the M×N carriers 2. The calculated correction values ​​are stored in the correction value storage unit 41 of each linear conveyor device 1.

[0064] As described above, in Embodiment 1, the linear conveying device 1 integrally forms the magnetic shielding part 20A and the magnet 10A, and the number of combinations of correction values ​​(correction value sets) used to correct the position of the carrier 2 is less than the number of carriers 2. Furthermore, the linear conveying device 1 corrects the position of any one of the carriers 2 using a common set of correction values ​​to the other carriers 2. Therefore, the linear conveying device 1 can easily suppress the decrease in position detection accuracy.

[0065] Implementation method 2.

[0066] Next, use Figure 5 Embodiment 2 will be described. In Embodiment 2, the magnet is provided with a taper.

[0067] Figure 5 This is a side view showing the structure of the magnet section of the linear conveying device according to Embodiment 2. Regarding... Figure 5 The realization and Figure 2 The same structural elements of the linear conveying device 1 shown in Embodiment 1 are labeled with the same reference numerals, and repeated descriptions are omitted.

[0068] Compared to the linear conveying device 1 of Embodiment 1, the linear conveying device 1 of Embodiment 2 has a magnet part MB instead of the magnet part MA. The linear conveying device 1 of Embodiment 2 has a magnet part MB in each of the plurality of carriers 2, but... Figure 5 The middle image shows a magnet part MB.

[0069] The magnet section MB includes 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 is in close contact with the magnet 10B. Similar to Embodiment 1, the magnet 10B has a facing surface opposite to the transport track 5, an upper surface opposite to the facing surface, and two other side surfaces besides the two end surfaces in the direction of movement.

[0070] When viewed from the Y-axis, the two end faces 61 and 62 of the magnet 10B in the magnet section MB, along the direction of movement of the magnet section MB (the direction of movement of the carrier 2), form an inclined conical shape. Due to this conical shape, the width of the magnet 10B in the X-axis direction (width in the direction of movement) gradually decreases from the upper surface side of the magnet 10B towards the opposite surface side. That is, the width of the magnet 10B gradually tapers from the positive Z-direction towards the negative Z-direction. The cone angle (taper ratio) of the magnet 10B is the cone angle from which the desired magnetic flux density waveform can be obtained.

[0071] When viewed from the Y-axis direction, the magnetic shielding portion 20B of the magnet part MB has an inverted conical shape at its two end faces 61 and 62 along the moving direction of the magnet 10B. Due to the inverted conical shape of the inner surface of the magnetic shielding portion 20B, the width of the magnetic shielding portion 20B in the X-axis direction (width in the moving direction) gradually increases from the upper surface side of the magnet 10B towards the opposite surface side. That is, the width of the side magnetic shielding portion gradually increases from the positive Z-direction towards the negative Z-direction. The inverted cone angle of the magnetic shielding portion 20B is such that a desired magnetic flux density waveform can be obtained.

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

[0073] The tapered shape of magnet 10B, where the width gradually narrows from the upper surface towards the opposite side, is difficult to achieve using the methods M1 and M2 described above. That is, in method M1, which forms the magnetic shielding portion by bending a plate-shaped magnet, and in method M2, which forms the magnetic shielding portion by cutting a block of magnet, it is impossible to achieve a seamless fit between the magnetic shielding portion and the tapered magnet 10B.

[0074] As described above, in Embodiment 2, the conical magnet 10B and the magnetic shielding portion 20B are integrally formed, thus enabling a structure in which the conical magnet 10B and the inverted conical magnetic shielding portion 20B are tightly attached. Furthermore, by tightly attaching the conical magnet 10B and the inverted conical magnetic shielding portion 20B, the magnetic flux density waveform can be adjusted to a desired shape.

[0075] Furthermore, the upper surface of the magnet 10B is larger on the opposite side of the magnet 10B compared to the opening between the magnetic shielding portion 20B and the side of the magnetic shielding portion 20B. Therefore, the magnet 10B and the magnetic shielding portion 20B can be prevented from separating when the magnet part MB moves at high speed or turns. That is, the cone-shaped magnet 10B facing the negative Z direction and the inverted cone-shaped magnetic shielding portion 20B facing the negative Z direction are in close contact, thus the magnet part MB can prevent the magnet 10B from detaching.

[0076] Implementation method 3.

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

[0078] Figure 6 This is a side view showing the structure of the magnet section of the linear conveying device according to Embodiment 3. Regarding... Figure 6 The realization and Figure 2 The same structural elements of the linear conveying device 1 shown in Embodiment 1 are labeled with the same reference numerals, and repeated descriptions are omitted.

[0079] Compared to the linear conveying device 1 of Embodiment 1, the linear conveying device 1 of Embodiment 3 has a magnet section MC instead of the magnet section MA. The linear conveying device 1 of Embodiment 3 has a magnet section MC in each of the plurality of carriers 2, but... Figure 6 The middle image shows a magnet part MC.

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

[0081] When viewed from the Y-axis direction, the side magnetic shielding portions 20C of the magnet section MC, arranged on both ends of the magnet 10A in the direction of movement, are conical. In the direction from the upper surface of the magnet 10A towards the opposite surface (negative Z-axis direction), the end of the inner side of each side magnetic shielding portion on the opposite surface is longer than the end of the outer side opposite to the inner side. The surface connecting these ends of the inner and outer sides is called an inclined surface. That is, the front ends 63 and 64 of the side magnetic shielding portions in the negative Z-direction of the magnetic shielding portion 20C, through the conical shape of the inclined surface of the opposite surface of the magnet 10A in the side magnetic shielding portion, have a width in the X-axis direction (width in the direction of movement) that gradually decreases from the upper surface of the magnet 10A towards the opposite surface. In other words, the front ends 63 and 64 of the side magnetic shielding portions in the negative Z-direction gradually become narrower from the positive Z-direction towards the negative Z-direction. The cone angle of the magnetic shielding part 20C is a cone angle that can obtain the desired magnetic flux density waveform.

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

[0083] As described above, in Embodiment 3, by bringing the magnet 10A and the cone-shaped magnetic shielding portion 20C into close contact, the magnetic flux density waveform can be adjusted to the desired shape.

[0084] The structure shown in the above embodiments is an example, and it can also be combined with other known technologies, and the embodiments can be combined with each other. Without departing from the spirit of the subject, some parts of the structure can be omitted or changed.

[0085] In Embodiment 1 described above, the linear conveying device 1 was manufactured by integrally molding the magnet 10A and the magnetic shielding part 20A. However, the magnet 10A and the magnetic shielding part 20A can also be manufactured by methods other than integral molding. For example, the manufacturing method of the linear conveying device 1 involves precisely cutting out the magnet 10A and the magnetic shielding part 20A from a block of magnets using precision machining such as laser processing. Furthermore, the manufacturing method of the linear conveying device 1 involves magnetizing the cut-out magnet 10A to form the magnet 10A, and assembling the cut-out magnetic shielding part 20A and the magnet 10A to form the magnet part MA. Then, the manufacturing method of the linear conveying device 1 involves assembling a carrier 2 containing the magnet part MA, and calculating a set of correction values ​​(signal correction values, position correction values, etc.) 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 described above, individual fluctuations in the size of the magnetic shielding part 20A and its positional relationship relative to the magnet 10A are reduced, and disturbances in magnetic flux or magnetic lines of force can be suppressed. Furthermore, fluctuations in the shape accuracy of the magnet part MA can be suppressed. The linear conveying device 1 can correct the position of any of the carriers 2 using a common set of correction values ​​to other carriers 2, thus suppressing increases in the cost and manufacturing cost of the linear conveying device 1, and easily suppressing the decrease in position detection accuracy.

[0087] Explanation of the label

[0088] 1 Linear conveying device, 2, 2-1 to 2-n carrier, 4 stator, 5 conveying track, 10A and 10B magnets, 20A to 20C magnetic shielding part, 30 magnetic detection element, 40 calculation unit, 41 correction value storage unit, 50 servo amplifier, 61 and 62 end faces, 63 and 64 front end, MA to MC magnet part, mV movable part.

Claims

1. A linear conveyor, characterized by, have: The conveying path has a stator; Multiple conveyor bodies that move along the conveying path; A magnet is mounted on the conveyor body to generate a magnetic field for position detection. A magnetic detection element is installed in the conveying path to detect the magnetic field; The computing unit calculates the position of the transport body based on the magnetic field detected by the magnetic detection element; and The correction value storage unit stores combinations of correction values ​​used to correct the position of the conveyor, i.e., correction value sets. The magnet portion has: Magnets, configured such that different magnetic poles are alternately arranged along the direction of movement of the conveyor; as well as The magnetic shielding portion of the magnet is formed of resin containing magnetic powder and is disposed on the two end faces of the magnet in the direction of movement and on the upper surface of the magnet opposite to the opposite face of the magnet opposite to the transport path, thereby shielding the magnetic lines of force from the magnet. The number of the correction value groups is less than the number of the conveyors. The calculation unit uses the set of correction values ​​used to correct the position of at least one of the conveyors as a set of correction values ​​used to correct the position of the other conveyors to correct the position. The magnet is a cone-shaped structure in which the width of its two end faces in the direction of movement decreases from the upper surface side towards the opposite surface side. The magnetic shielding portion disposed on the two end faces of the magnet is an inverted cone shape whose inner wall surface in the moving direction is inclined such that its width in the moving direction increases from the upper surface side towards the opposite surface side. The two end faces of the magnet in the direction of movement are each in close contact with the inner wall surface of the magnetic shielding part.

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

3. The linear conveying device according to claim 1, characterized in that, The number of correction value groups is 1. The calculation unit corrects the position for all of the conveyor bodies using a common set of correction values.

4. The linear conveying device according to claim 1, characterized in that, The corner of the upper surface of the magnet and the corner of the inner wall of the magnetic shielding part that contacts the corner are closely attached.

5. The linear conveying device according to claim 1, characterized in that, The correction value is a signal correction value used to correct the signal of magnetic flux density detected by the magnetic detection element.

6. The linear conveying device according to claim 1, characterized in that, The correction value is a position correction value used to correct the position of the transport body itself, calculated based on the signal of magnetic flux density detected by the magnetic detection element.

7. The linear conveying device according to claim 2, characterized in that, The magnetic shielding part and the magnet are fixed and held together by the integral molding.

8. The linear conveying device according to claim 1, characterized in that, The magnetic shielding portion disposed on the two end faces of the magnet has an end on the opposite side of the inner side in the direction of movement (from the upper surface side towards the opposite side) that is longer than the end on the opposite side of the outer side opposite to the inner side in the direction of movement. The surface connecting the ends on the opposite sides of the inner and outer sides is called an inclined surface.

9. A manufacturing method of a linear conveyance device, which is the manufacturing method of a linear conveyance device as claimed in any one of claims 1 to 8, characterized by, Include: The molding step involves integrally molding the magnet and the magnetic shielding part; and The correction value storage step involves storing the correction value group in the correction value storage unit.

10. The method for manufacturing the linear conveying device according to claim 9, characterized in that, The molding step includes: In the first forming step, magnetic material flows into the first mold to form the magnet; and In the second forming step, the magnet enters the second mold, and magnetic material resin flows in relative to the magnet to form the magnetic shielding part.

11. The method for manufacturing the linear conveying device according to claim 9, characterized in that, The molding step includes: In the first forming step, magnetic material resin flows into the first mold to form the magnetic shielding portion; and In the second forming step, the magnetic shielding part enters the second mold, and magnetic material flows in relative to the magnetic shielding part to form the magnet.

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