Linear transport device and method for producing a linear transport device

Abstract

A linear transport device (1) comprises a transport path including a stator, a plurality of transport bodies moving along the transport path, a magnetizer (MA) installed on each of the transport bodies and generating a magnetic field to be used in position detection, a magnetic detection element (30) installed on the transport path and detecting the magnetic field, a computing device (40) calculating the position of each of the transport bodies based on the magnetic field detected by the magnetic detection element, and a correction value memory storing a correction value set which is a combination of correction values for correcting the position of each of the transport bodies.The magnetizer comprises a magnet (10A) in which magnetic poles of different polarities are alternately arranged along a moving direction of the transport bodies, and a magnetic shield (20A) which is a magnetic body and formed of a resin containing a magnetic material powder. The magnetic shield (20A) blocks magnetic lines of force emanating from the magnet by being provided on two end surfaces of the magnet and on an upper surface of the magnet in the moving direction, the upper surface being a surface opposite a counter surface facing the transport path. The number of correction value sets is smaller than the number of transport bodies. The computing device corrects the position of one of the transport bodies using one of the correction value sets commonly applicable to another of the transport bodies.

Description

Area

[0001] The present disclosure relates to a linear transport device that detects the positions of movers and a method for manufacturing the linear transport device. background

[0002] To precisely control the position of a slider, a linear transport device includes position detectors for detecting the position of a slider based on the magnetic energy of a magnet disposed on the slider. In such a linear transport device, the presence of approaching sliders causes magnetic interference between magnets, resulting in a reduction in the accuracy of the position detection performed by the position detectors. In addition, due to factors such as dimensional tolerance in the manufacturing process of the sliders, a linear transport device is subject to variation in the position detection value among the position detectors, which also leads to a reduction in the accuracy of the position detection.

[0003] The position detector described in Patent Literature 1 includes a magnetic shield for suppressing magnetic interference between magnets of approaching movers, the magnetic shield being provided at end portions in the moving direction and at a back surface of the position detecting magnet included in each of the movers. Citation listPatent literature

[0004] Patent Literature 1: Japanese Patent No. 7 046 290 Brief description of the inventionProblem to be solved by the invention

[0005] However, the above-described technology of Patent Literature 1 has difficulty in accurately forming a corner portion on an inner surface of the magnetic shield, where, in the magnetic shield, an inner surface facing the position detecting magnet of a rear magnetic shield portion provided on the rear surface meets an inner surface facing the position detecting magnet of a side magnetic shield portion provided on a side surface, into a desired shape.That is, forming the corner portion into the shape of the magnet with high accuracy is difficult in both cases: the case where the magnetic shield is formed by bending a plate-shaped magnetic body into a shape covering the back surface and two side surfaces of the magnet; and the case where the magnetic shield is formed by cutting a block of magnetic material into a shape covering the back surface and two side surfaces of the magnet. This may create a gap between the magnet and the magnetic shield due to dimensional tolerance, causing irregularities in the magnetic flux or magnetic lines of force. This poses a problem in the form of a reduction in position detection accuracy.

[0006] The present disclosure has been made in view of the foregoing, and it is an object of the present disclosure to provide a linear transfer device capable of preventing a reduction in position detection accuracy. Means to solve the problem

[0007] To solve the problem and achieve the above-described object, a linear transporter of the present disclosure includes: a transport path including a stator; a plurality of transport bodies moving along the transport path; a magnetizer installed on each of the transport bodies and configured to generate a magnetic field to be used in position detection; and a magnetic detection element installed on the transport path to detect the magnetic field. The linear transporter of the present disclosure further includes: a computing device.calculator) configured to calculate a position of each of the transport bodies based on the magnetic field detected by the magnetic detection element; and a correction value memory configured to store a correction value set that is a combination of correction values ​​for correcting the position of each of the transport bodies. The magnetizer comprises: a magnet in which magnetic poles of different polarities are alternately arranged along a moving direction of the transport bodies; and a magnetic shield, which is a magnetic body and is formed from a resin containing a magnetic material powder, wherein the magnetic shield blocks magnetic lines of force emanating from the magnet by being provided at two end faces (front faces) in the moving direction.end surfaces) of the magnet and on an upper surface of the magnet, wherein the upper surface is a surface opposite a counter surface facing the transport path. The number of correction value sets is smaller than the number of transport bodies. The computing device corrects the position of one of the transport bodies using a correction value set that is equally applicable to another of the transport bodies. Effects of the invention

[0008] A linear transport device according to the present disclosure provides an advantage of avoiding a reduction in accuracy in position detection. Short description of the drawings Fig. 1 is a perspective view illustrating a configuration of a linear transfer device according to a first embodiment. Fig. 2 is a side view illustrating a configuration of a magnetizer included in the linear transport device according to the first embodiment. Fig. 3 is a block diagram showing the configuration of the linear transport device according to the first embodiment. Fig. 4 is a flowchart illustrating a process flow of manufacturing the linear transport device according to the first embodiment. Fig. 5 is a side view illustrating a configuration of a magnetizer included in the linear transport device according to a second embodiment. Fig. 6 is a side view illustrating a configuration of a magnetizer included in the linear transport device according to a third embodiment. Description of embodiments

[0009] A linear transport device and a method for manufacturing the linear transport device according to embodiments of the present disclosure will be described in detail below with reference to the drawings. First embodiment

[0010] Fig. 1 is a perspective view illustrating a configuration of a linear transfer device according to a first embodiment. Fig. Fig. 2 is a side view illustrating a configuration of a magnetizer included in the linear transport device according to the first embodiment. Fig. 1 and Fig. In Figure 2, two mutually perpendicular axes in a plane parallel to the upper surface of a magnet 10A are represented as the X-axis and the Y-axis, and the axis perpendicular to both the X-axis and the Y-axis is represented as the Z-axis. For example, the plane parallel to the upper surface of the magnet 10A (i.e., the XY plane) is a horizontal plane, and the Z-axis direction is a vertical direction.

[0011] The linear transport device 1 comprises: several carrier devices 2 for transporting objects; a stator 4; magnetic detection elements 30; a computing device 40; and a servo amplifier 50.

[0012] Each support device 2 includes: a mover mV that generates a magnetic field for driving; and a magnetizer MA that generates a magnetic field to be used in position detection. The mover mV and the magnetizer MA are arranged in a lower portion of each of the support devices 2. Note that the support devices 2 are an example of transport bodies. The transport bodies may further each include another component in addition to the mover mV and the magnetizer MA included in each of the support devices 2.

[0013] The linear transport device 1 further comprises a transport rail 5 in which the stator 4 is installed. In the linear transport device 1, the support devices 2 are positioned so that they face the transport rail 5. That is, in the linear transport device 1, the slider mV is positioned so that it faces the stator 4. In the linear transport device 1, a movement of the slider mV above the stator 4 causes the corresponding one of the support devices 2 to move above the transport rail 5 in the transport direction.

[0014] The stator 4, which generates a magnetic field for driving, and the magnetic detection elements 30, which detect the positions of the carriers 2, are arranged on the transport rail 5. In the linear transport device 1, the slider mV and the stator 4 constitute a linear motor. One of the slider mV and the stator 4 may be formed using an electromagnet, and the other may be formed using an electromagnet or a permanent magnet. Note that the transport rail 5 is an example of a transport path. The transport path may additionally include other components as long as it includes the stator 4 and the magnetic detection elements 30 as the transport rail 5.

[0015] The magnetic detection elements 30 detect the magnetic field (i.e., the magnetic flux density) generated by the magnetizer MA. In the linear transport device 1, a set consisting of the magnetizer MA and the magnetic detection elements 30 forms a position detector for the linear transport device. In the linear transport device 1, the rotor mV and the stator 4 generate a magnetic field for driving, whereas the magnetizer MA generates a magnetic field to be used for position detection. In the linear transport device 1, movement of the rotor mV above the stator 4 causes the magnetizer MA to move above the magnetic detection elements 30 when the carrier device 2 moves along the transport rail 5.

[0016] The magnetizer MA includes: a magnet (permanent magnet) 10A in which magnetic poles of different polarities are alternately arranged; and a magnetic shield 20A that blocks magnetic lines of force emanating from the magnet 10A. The magnet 10A is arranged along the direction of movement of the rotor mV (i.e., the transport direction of the carrier device 2).

[0017] The magnetic field of magnet 10A is directed alternately in different directions along the direction of movement of support device 2. That is, magnet 10A comprises multiple magnetic poles formed in a single magnetic body arranged along the direction of movement of support device 2. Note that magnet 10A may be formed from multiple magnets arranged along the direction of movement. Magnet 10A has a rectangular parallelepiped shape. Fig. 2 illustrates one of the side surfaces of the magnet 10A, which has a rectangular parallelepiped shape. The magnet 10A is arranged in the support device 2 so as to include the plurality of magnetic poles arranged along a direction corresponding to the direction of movement of the support device 2.

[0018] In Fig. 2, the solid arrows 7 indicate the magnetic field generated by the magnet 10A. In addition, the arrows 11 shown as contours in the magnet 10A in Fig. 2 each indicates the direction of the magnetic field in the magnet 10A.

[0019] The magnetic shield 20A includes: side magnetic shield portions provided on two end surfaces of the magnet 10A in the moving direction (ie, the front surface and the rear surface in the moving direction); and an upper magnetic shield portion provided on an upper surface of the magnet 10A, the surface of which is a surface opposite a counter surface facing the transport rail 5. Perpendicular lines from the front surface and the rear surface of the magnetizer MA in the moving direction are parallel to the moving direction.

[0020] The end surfaces of the magnet 10A where the side magnetic shielding portions are provided are the front surface and the back surface of the magnet 10A. The surface of the magnet 10A where the top magnetic shielding portion is provided is the upper surface opposite the opposing surface facing the conveying rail 5. This configuration makes it possible to form the magnetic shield 20A such that the side magnetic shielding portions and the top magnetic shielding portion are connected to each other as viewed in the Y-axis direction, thereby forming a shape to cover the two end surfaces and the top surface of the magnet 10A.

[0021] Note that the upper surface of the magnet 10A, which is in close contact with the upper-side magnetic shield portion, can also be regarded as the back surface (back surface portion) of the magnet 10A when viewed from the transport rail 5. Furthermore, the inner wall surface of the upper-side magnetic shield portion, which is in close contact with the magnet 10A, can also be regarded as the lower surface of the magnetic shield 20A when viewed from the transport rail 5.

[0022] Of the outer wall surface of the magnet 10A, which has a rectangular parallelepiped shape, the surfaces parallel to the YZ plane are two side surfaces, in other words, the front surface and the back surface in the moving direction of the magnet 10A. Of the outer wall surface of the magnet 10A, which has a rectangular parallelepiped shape, the surfaces parallel to the XY plane are the upper surface and the lower surface of the magnet 10A. Furthermore, of the outer wall surface of the magnet 10A, which has a rectangular parallelepiped shape, the surfaces parallel to the XZ plane are the other two side surfaces of the magnet 10A.

[0023] In Fig. 1, the side magnetic shielding portions are in close contact with the magnet 10A at their end surfaces parallel to the YZ plane, and the top magnetic shielding portion is in close contact with the magnet 10A at its upper surface parallel to the XY plane. The side magnetic shielding portions cover the two end surfaces parallel to the YZ plane (i.e., the front surface and the back surface) of the magnet 10A, and the top magnetic shielding portion covers one of the surfaces parallel to the XY plane (i.e., the upper surface) of the magnet 10A.

[0024] Of the outer wall surface of the magnet 10A, which has a rectangular parallelepiped shape, the front surface, the back surface, and the top surface are in close contact with the inner wall surface of the magnetic shield 20A. That is, the angled portion formed by the top surface and the front surface of the magnet 10A, and the angled portion formed by the top surface and the back surface of the magnet 10A are covered by the inner wall surface of the magnetic shield 20A. Note that the angled portion formed by the top surface and the front surface of the magnet 10A and the angled portion formed by the top surface and the back surface of the magnet 10A are angled portions on an upper side of the magnet 10A.As described above, the linear transport device 1 is configured such that the corner portions of the inner wall surface of the magnetic shield 20A, which are in contact with the respective angled portions on an upper side of the magnet 10A, are in close contact with the respective angled portions on an upper side of the magnet 10A, thereby leaving no space between the magnetic shield 20A and the magnet 10A. Note that the inner wall surface of the magnetic shield 20A may cover both side surfaces other than the front surface and the back surface of the outer wall surface of the magnet 10A, which has a rectangular parallelepiped shape.

[0025] The magnetic shield 20A is formed of a material having a magnetic permeability greater than 1, such as iron. Specifically, the magnetic shield 20A is formed of a resin containing a magnetic material powder. In the first embodiment, the magnetic shield 20A, which includes a magnetic energy blocking portion, and the magnet 10A are formed by integral molding, thereby causing the magnetic shield 20A and the magnet 10A to be in close contact with each other without any space therebetween. This configuration causes the magnetic shield 20A and the magnet 10A to firmly hold each other. That is, the magnetic shield 20A firmly holds the magnet 10A, and the magnet 10A firmly holds the magnetic shield 20A.

[0026] During integral molding in the first embodiment, the magnet 10A is first formed by, for example, injection molding using a mold for the magnet 10A. That is, a magnetic material is poured into the mold for the magnet 10A, and the magnet 10A is thus formed. Then, the magnet 10A is placed in a mold for a magnetic material resin (i.e., for the magnetic shield 20A), and the magnetic material resin is poured into the mold for the magnetic material resin. The magnetic material resin mold has a cavity in a portion for forming the magnetic shield 20A and a portion for arranging the magnet 10A.With respect to this cavity portion, the magnet 10A is arranged in the magnet 10A arranging portion, and the resin of magnetic material is poured into the magnetic shield forming portion 20A, thereby causing the magnetic shield 20A to be molded integrally with the magnet 10A.

[0027] Note that during integral molding in the first embodiment, the magnetic shield 20A may be formed first. In this case, the magnetic shield 20A is first formed using the mold for the magnetic shield 20A by injection molding. That is, the magnetic material resin is poured into the mold for the magnetic material resin, and the magnetic shield 20A is thus formed. Then, the magnetic shield 20A is arranged in the mold for the magnet 10A, and the magnetic material is poured into the mold for the magnet 10A. The mold for the magnet 10A has a cavity in a portion for forming the magnet 10A and in a portion for disposing the magnetic shield 20A.With respect to this cavity portion, the magnetic shield 20A is arranged in the magnetic shield 20A arranging portion, and the magnetic material is poured into the magnet 10A forming portion, thereby causing the magnet 10A to be formed integrally with the magnetic shield 20A.

[0028] In the case where the magnet 10A is formed before the magnetic shield 20A is formed, the mold for the magnet 10A is a first mold, and the mold for the magnetic shield 20A is a second mold. Alternatively, in the case where the magnetic shield 20A is formed before the magnet 10A is formed, the mold for the magnetic shield 20A is the first mold, and the mold for the magnet 10A is the second mold.

[0029] 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 amount of a signal output. An example of the magnetic detection element 30 is a Hall element. The magnetic detection element 30 sends information about the detected magnetic field to the computing device 40. The plurality of magnetic detection elements 30 are installed on the transport rail 5 along the moving direction of the magnetizer MA. The magnetic field detected by each of the magnetic detection elements 30 varies as the magnetizer MA moves.

[0030] The computing device 40 calculates the position (position data) of the support device 2 (magnetizer MA) based on a detection value of the magnetic flux (e.g., the magnetic flux density) transmitted by the magnetic sensing element 30. The position of the support device 2 corresponds to the position of the magnet 10A and the position of the rotor mV. The computing device 40 sends the position data related to the support device 2 to the servo amplifier 50.

[0031] Fig. Fig. 3 is a block diagram illustrating a configuration of the linear transport device according to the first embodiment. The linear transport device 1 includes a plurality of support devices 2-1 to 2-n (where n is a natural number greater than or equal to 2). The support devices 2-1 to 2-n are shown in Figs. Fig. 2 described support devices 2. In the description of the first embodiment, the support devices 2-1 to 2-n may be referred to as support devices 2 if no distinction needs to be made between the support devices 2-1 to 2-n. The support devices 2-1 to 2-n each comprise the magnets 10A, which have a similar shape, and the magnetic shields 20A (in Fig. 3 not shown), which have the same shape.

[0032] In the linear transport device 1, the carrier devices 2-1 to 2-n move along the transport rail 5. The magnetic detection element 30 detects the magnetic field generated by the magnet 10A contained in the respective one of the carrier devices 2-1 to 2-n when each of the carrier devices 2-1 to 2-n passes over the magnetic detection element 30. The magnetic detection element 30 transmits the detected magnetic field to the computing device 40.

[0033] The computing device 40 includes a correction value memory 41. The correction value memory 41 stores in advance a correction value for correcting the positions of the carrier devices 2-1 to 2-n. This correction value is a correction value (error correction value) for detecting the position of the magnet 10A with high accuracy. Note that the correction value memory 41 may be arranged externally of the computing device 40.

[0034] The correction value for correcting the positions of the carrier devices 2-1 to 2-n can be: a correction value for correcting a signal representing the magnetic flux density (i.e., a signal correction value); or a correction value for correcting the positions of the carrier devices 2-1 to 2-n themselves, which is calculated from the signal representing the magnetic flux density (i.e., a position correction value). The following description describes the case where the correction value for correcting the positions of the carrier devices 2-1 to 2-n is a signal correction value, which is a correction value for correcting the signal representing the magnetic flux density.

[0035] For example, when the magnetic flux density of the magnet 10A of each carrier 2-1 to 2-n detected by the magnetic detection element 30 is represented by a sine wave signal, correction values ​​for correcting values ​​such as the amplitude and offset of the sine wave signal are each a signal correction value for correcting the positions of the carrier 2-1 to 2-n. The calculation device 40 corrects values ​​such as the amplitude and offset of the sine wave signal using signal correction values ​​stored in the correction value memory 41. Let B denote the magnetic flux density of the magnet 10A of each carrier 2-1 to 2-n, this magnetic flux density is represented, for example, as B = P sinθ + Q, where P is the amplitude and Q is the offset. The offset is a deviation from a center value “0” of the average value.average value) of the signal waveform. The signal correction values ​​are obtained in advance and stored in the correction value memory 41 before delivery of the linear transport device 1.

[0036] The computing device 40 corrects the signal representing the magnetic flux density transmitted from each of the magnetic detection elements 30 using the signal correction values ​​stored in the correction value memory 41. The computing device 40 calculates the position data with respect to the carrier devices 2-1 to 2-n based on a signal obtained by correcting the signal representing the magnetic flux density. The computing device 40 sends the position data with respect to the carrier devices 2-1 to 2-n to the servo amplifier 50.

[0037] The signal correction values ​​stored in advance in the correction value memory 41 are values ​​common to the carriers 2-1 to 2-n. Note that it is sufficient that signal correction values ​​commonly applicable to at least two of the carriers 2-1 to 2-n are used in the linear transport device 1. That is, it is sufficient that the number of sets of signal correction values ​​(e.g., sets of correction values ​​for amplitude and correction values ​​for displacement) to be stored in advance in the correction value memory 41 is smaller than the number of carriers 2-1 to 2-n. That is, it is sufficient that the number of correction value sets, each of which is a combination of correction values, is smaller than the number of carriers 2-1 to 2-n. The following description describes a case where there is (exactly) one correction value set.It should be noted that the correction values ​​included in the correction value set may be of one type or of multiple types.

[0038] The servo amplifier 50 controls the linear motor based on the position data relative to the carrier device 2. Such control causes the electrical energy supplied to the stator 4 to be adjusted to an electrical energy suitable for the position of the slider mV. Adjusting the electrical energy supplied to the stator 4 provides an adjustment of the magnitudes of the magnetic fields generated by the slider mV and by the stator 4 for driving, thereby providing an adjustment of the position of the slider mV. In other words, the carrier device 2 moves along the transport rail 5.

[0039] In the first embodiment, the magnetic shield 20A and the magnet 10A are formed by integral molding, causing the magnetic shield 20A and the magnet 10A to be in close contact with each other without any space therebetween. Thus, the linear transport device 1 includes no space between the magnetic shield 20A and the magnet 10A, thereby preventing the occurrence of an irregularity in the magnetic flux or an irregularity in the magnetic lines of force. This enables the linear transport device 1 to: acquire sine wave signals similar to each other from the respective carrier devices 2-1 to 2-n; and correct the sine wave signals using signal correction values ​​commonly applicable to the carrier devices 2-1 to 2-n.

[0040] Furthermore, performing integral molding to form the magnetic shield 20A and the magnet 10A of the linear transport device 1 can prevent manufacturing variations in the shapes of the magnetic shield 20A and the magnet 10A, and can easily bring the magnetic shield 20A and the magnet 10A into close contact with each other without any space between them. This can prevent the occurrence of irregularities in the magnetic flux or irregularities in the magnetic lines of force.

[0041] When one of the support devices 2 that is not the target of position detection is away from the support device 2 that is the target of position detection, the magnetic detection element 30 detects only the magnetic field generated by the magnet 10A of the support device 2 that is the target of position detection, and does not detect the magnetic field generated by the magnet 10A of the support device 2 that is not the target of position detection.

[0042] When a support device 2 that is not the target of position detection comes close to the support device 2 that is the target of position detection, the magnetic detection element 30 detects the magnetic field generated by the magnet 10A of the support device 2 that is not the target of position detection if the support device 2 that is not the target of position detection does not include the magnetic shield 20A. In this case, the accuracy in detecting the position of the support device 2 is reduced.

[0043] The linear transport device 1 of the first embodiment includes the magnetic shield 20A in each of the support devices 2, and can therefore prevent a reduction in position detection accuracy. That is, since the linear transport device 1 includes the magnetic shield 20A, the magnetic force generating small loops of magnetic force from the magnet 10A of a support device 2 that is not the target of position detection is blocked by the side magnetic shield portions, thereby preventing it from reaching the magnetic detection element 30.Moreover, since the linear transfer device 1 includes the magnetic shield 20A, the magnetic force generating large loop magnetic lines of force from a carrier device 2, which is not the target of position detection, is blocked by the upper-side magnetic shield portion and is thereby prevented from reaching the magnetic detection element 30.

[0044] Apart from that, there is a method for forming the magnetic shield by bending a plate-shaped magnetic body (hereinafter referred to as method M1). The method M1 involves a bending radius (corner radius) that occurs in a bent portion due to a manufacturing tolerance when the plate-shaped magnetic body is bent. This prevents the magnet from coming into close contact with the bent portion of the magnetic shield (i.e., the corner portion of the inner surface of the magnetic shield facing the angled portion of the magnet). Thus, the method M1 causes an air gap between the magnet and the magnetic shield, thereby causing irregularity in the magnetic flux or magnetic lines of force. Such irregularity in the magnetic flux or magnetic lines of force may result in variation in the position detection values ​​from the position detector.This reduces the accuracy of detecting the position of a support device. Furthermore, the M1 method has difficulties performing shallow bending. This requires the dimension of the lateral magnetic shield sections to reach or exceed a certain value in the depth direction, making thickness reduction difficult.

[0045] In addition, there is a method for forming the magnetic shield by cutting a block of magnetic material into a rectangular U-shape (hereinafter referred to as method M2). The M2 method cannot form the corner portion of the bottom of the rectangular U-shaped portion (that is, the corner portion of the inner surface of the magnetic shield facing the angled portion of the magnet) to have a right angle due to a manufacturing tolerance, and leaves a curved surface or a C-shaped surface in the corner portion of the bottom of the rectangular U-shaped portion. This prevents the magnet from coming into close contact with the corner portion of the inner surface of the magnetic shield. Thus, the M2 method causes an air gap between the magnet and the magnetic shield, causing irregularity in the magnetic flux or magnetic lines of force.Such irregularities in the magnetic flux or magnetic lines of force can lead to variations in the position detection values ​​from the position detector. This reduces the accuracy of detecting the position of a supporting device. Furthermore, the magnetic material block is formed from a metal that is harder than aluminum or brass, making the machining process more time-consuming and costly.

[0046] As described above, both methods M1 and M2 cause an error in the relative position between the magnet and the magnetic shield due to a manufacturing tolerance of a component (particularly the magnetic shield), thereby causing a variation in the magnetic fields generated by the respective carriers. Thus, when carriers manufactured using either method M1 or M2 are used in the linear transfer device, avoiding a reduction in the accuracy of detecting the positions of the carriers requires calculating signal correction values ​​on a per-carrier basis during an acceptance test and requires storing the signal correction values ​​in advance in the correction value memory.For example, if a single linear transport device supports 100 carriers (N = 100), the correction value memory must store signal correction values ​​for the magnets of the 100 carriers in advance, which requires a very high-capacity memory. Furthermore, determining signal correction values ​​for 100 magnets requires a long calculation time and a large amount of work, which increases the manufacturing cost of the linear transport device.

[0047] In contrast, in the first embodiment, the magnet 10A and the magnetic shield 20A are formed by integral molding, which involves molding a magnetic material and a resin of magnetic material. This causes the magnet 10A and the magnetic shield 20A to be brought into close contact with each other. This prevents an air gap from occurring between the magnet 10A and the magnetic shield 20A, and thus prevents a relative positional offset from occurring between the magnet 10A and the magnetic shield 20A. This eliminates variation in the magnetic fields generated by the magnetizers MA, thereby enabling the linear transport device 1 to prevent a reduction in the accuracy in detecting the position of the magnet 10A of each of the carrier devices 2. Furthermore, in the first embodiment, the manufacture of the resin mold (ie,the mold for the magnetic shield 20A), which is a mold for the resin of magnetic material, can reduce the manufacturing tolerance of the magnetic shield 20A with high precision.

[0048] As described above, the linear transport device 1 in the first embodiment can prevent variation in the magnetic fields generated by the magnets 10A of the N carrier devices 2. Accordingly, storing one kind of set of signal correction values ​​in the correction value memory 41 is sufficient. This significantly reduces the storage capacity required for the correction value memory 41 and can reduce the cost of the linear transport device 1. This can also reduce the time required to determine the signal correction values ​​and thus reduce the manufacturing cost of the linear transport device 1.

[0049] Moreover, in the first embodiment, the magnetic shield 20A is formed by integral molding with the magnet 10A using a resin containing a magnetic material powder (ie, a resin with a magnetic material powder), thereby enabling the magnet 10A to have a thickness smaller than the thickness achieved by the method M1.

[0050] Furthermore, in the first embodiment, the magnetic shield 20A is formed by integral molding with the magnet 10A using a resin containing a magnetic material powder, thereby allowing the magnetic shield 20A and the magnet 10A to be brought into close contact with each other without any space in between over all surfaces where the magnetic shield 20A and the magnet 10A face each other, including the corner portions of the inner surface of the magnetic shield 20A. This can increase the accuracy in detecting the position of the magnet 10A compared to when either of the methods M1 and M2 is used, and can reduce costs by reducing the processing time in the first embodiment.

[0051] Furthermore, magnets and rotational angle sensors have a one-to-one relationship when considering a case of a rotation angle detection device for detecting a rotation angle of a motor shaft (a rotating body). Accordingly, one (1) set of signal correction values ​​is sufficient to correct the positions of magnets. In contrast, the linear transfer device 1 includes the plurality of (N) carrier devices 2, each including the rotor mV. This results in an N-to-one relationship (where N ≥ 2) between the magnets 10A used for position detection and the magnetic detection element 30. That is, each of the magnetic detection elements 30 detects the positions of the N magnets 10A. Thus, if the magnet 10A and the magnetic shield 20A are subject to large manufacturing variation, this requires that N correction values ​​be stored in advance in the correction value memory 41.In the first embodiment, the magnet 10A and the magnetic shield 20A are subject to a small manufacturing variation, and thus it is sufficient to store a single correction value in advance in the correction value memory 41.

[0052] As described above, in the first embodiment, the magnetic shield 20A is formed by integral molding with the magnet 10A using a resin containing a magnetic material powder, thereby reducing the variation between individual components in the dimension of the magnetic shield 20A and in the positional relationship of the magnetic shield 20A relative to the magnet 10A. This makes it possible to avoid variation in shape accuracy between the magnetizers MA, and thus enables the linear transfer device 1 to provide high-accuracy positioning using one (single) type of correction value.

[0053] Next, a process sequence for manufacturing the linear transport device 1 is described. Fig. 4 is a flowchart illustrating a process flow for manufacturing the linear transfer device according to the first embodiment. The linear transfer device 1 of the first embodiment is manufactured by forming the magnet 10A and the magnetic shield 20A by integral molding (step S10). N sets of the magnets 10A and the magnetic shields 20A formed by integral molding are manufactured. The support devices 2-1 to 2-n, each including the magnet 10A and the magnetic shield 20A formed by integral molding, are manufactured.

[0054] One (1) set of correction values ​​(ie, a signal correction value, a position correction value, and / or the like) is calculated for the set of N carrier devices 2-1 to 2-n. The calculated correction values ​​are stored in the correction value memory 41 of the linear transport device 1 (step S20).

[0055] Note that if M (where M is a natural number greater than or equal to 2) linear transfer devices 1 are to be manufactured, M × N sets of magnets 10A and magnetic shields 20A formed by integral molding are manufactured. Then, one (1) correction value is calculated for the M × N carrier devices 2. The calculated correction value is stored in the correction value memory 41 of each of the linear transfer devices 1.

[0056] As described above, the linear transfer device 1 of the first embodiment includes the magnetic shield 20A and the magnet 10A formed by integral molding, and the number of combinations of correction values ​​(i.e., correction value sets) for correcting the positions of the carriers 2 is smaller than the number of carriers 2. In addition, the linear transfer device 1 corrects the position of one of the carriers 2 by applying a correction value set to one of the carriers 2 that is commonly applicable to another of the carriers 2. This enables the linear transfer device 1 to easily prevent a reduction in position detection accuracy. Second embodiment

[0057] Next, a second embodiment will be described with reference to Fig. 5. In the second embodiment, the magnet is beveled.

[0058] Fig. Fig. 5 is a side view illustrating a configuration of a magnetizer included in the linear transport device according to the second embodiment. The same reference numerals are used to denote components of the components of Fig. 5, which provide the same functionality as the corresponding components of the linear transport device 1 of the Fig. 2, and duplicate description thereof will be omitted.

[0059] The linear transport device 1 of the second embodiment contains a magnetizer MB instead of the magnetizer MA of the linear transport device 1 of the first embodiment. The linear transport device 1 of the second embodiment contains the magnetizer MB in each of the plurality of carrier devices 2, wherein in Fig. 5 one of the magnetizers MB is shown.

[0060] The magnetizer MB includes a magnet 10B and a magnetic shield 20B. Also in the case of the magnetizer MB, the magnetic shield 20B is formed by integral molding with the magnet 10B, and the magnetic shield 20B is thus in close contact with the magnet 10B. The magnet 10B, similar to the first embodiment, has a counter surface facing the transport rail 5, an upper surface opposite the counter surface, and two end surfaces and two further side surfaces in the moving direction.

[0061] The magnet 10B of the magnetizer MB is tapered in the Y-axis direction such that its two end surfaces 61 and 62 are inclined in the moving direction of the magnetizer MB (the moving direction of the support devices 2). Because of the tapered shape, the magnet 10B has a width in the X-axis direction (i.e., a width in the moving direction) that gradually decreases in a direction from the upper surface of the magnet 10B to the opposite surface of the magnet 10B. That is, the magnet 10B has a width that gradually decreases in a direction from the positive Z direction to the negative Z direction. The taper angle (taper ratio) of the magnet 10B is a taper angle that can provide a desired magnetic flux density waveform.

[0062] The magnetic shield 20B of the magnetizer MB has a shape in which its side magnetic shield portions, provided on the two end surfaces 61 and 62 in the moving direction of the magnetizer MB in the moving direction of the magnet 10B, are inversely tapered when viewed in the Y-axis direction. Since it is inversely tapered such that the inner surfaces of the side magnetic shield portions are inclined, the magnetic shield 20B has a width in the X-axis direction (i.e., a width in the moving direction) that gradually increases in a direction from the top surface of the magnet 10B to the opposite surface of the magnet 10B. That is, the side magnetic shield portions each have a width that gradually increases in a direction from the positive Z direction to the negative Z direction.The reverse taper angle of the magnetic shield 20B is a reverse taper angle that can provide a desired magnetic flux density waveform.

[0063] As described above, the magnetic shield 20B is formed such that the width of the magnet 10B in the X direction gradually decreases in a direction from the upper surface of the magnet 10B to the opposite surface of the magnet 10B; and the width of the magnetic shield 20B gradually increases in the X direction in a direction from the upper surface of the magnet 10B to the opposite surface of the magnet 10B. This means that the upper surface of the magnet 10B is larger than the opening of the magnetic shield 20B. Furthermore, in the magnetizer MB, the end surfaces of the magnet 10B in its moving direction are in close contact with the inner wall surfaces of the magnetic shield 20B in its moving direction. This means that the reverse taper angle of the magnetic shield 20B is an angle corresponding to the taper angle of the magnet 10B.

[0064] The tapered shape in which the width of the magnet 10B gradually decreases in the direction from the upper surface of the magnet 10B to the counter surface of the magnet 10B is difficult to form using the methods M1 and M2 described above. That is, using either the method M1 or the method M2 does not allow the magnet 10B having a tapered structure to be brought into close contact with the magnetic shield without a space therebetween, wherein the method M1 is a method of forming the magnetic shield by bending a plate-shaped magnetic body, and wherein the method M2 is a method of forming the magnetic shield by cutting a block of magnetic material.

[0065] As described above, in the second embodiment, the magnet 10B having a tapered shape and the magnetic shield 20B are formed by integral molding, thereby enabling a structure to be provided in which the magnet 10B having a tapered shape and the magnetic shield 20B having a reverse tapered shape are in close contact with each other. Bringing the magnet 10B having a tapered shape and the magnetic shield 20B having a reverse tapered shape into close contact with each other enables the magnetic flux density waveform to have a desired shape.

[0066] Furthermore, the magnetizer MB is configured such that the upper surface of the magnet 10B is larger than the opening provided between the side magnetic shield portions of the magnetic shield 20B on the side closer to the opposing surface of the magnet 10B. This can prevent the magnet 10B from detaching from the magnetic shield 20B when the magnetizer MB moves rapidly or the magnetizer MB moves along a curve. That is, the magnet 10B, which has a tapered shape in the negative Z direction, and the magnetic shield 20B, which has a reverse tapered shape in the negative Z direction, are in close contact with each other, and the magnetizer MB can therefore prevent the magnet 10B from falling off. Third embodiment

[0067] Next, a third embodiment will be described with reference to Fig. 6. In the third embodiment, the magnetic shield is beveled.

[0068] Fig. Fig. 6 is a side view illustrating a configuration of a magnetizer included in the linear transport device according to the third embodiment. The same reference numerals are used to denote components of the components of Fig. 6 which have the same functionality as the functionality of the corresponding components of the linear transport device 1 of the Fig. 2, and duplicate description thereof will be omitted.

[0069] The linear transport device 1 of the third embodiment comprises a magnetizer MC instead of the magnetizer MA of the linear transport device 1 of the first embodiment. The linear transport device 1 of the third embodiment contains the magnetizer MC in each of the plurality of carrier devices 2, but Fig.6 represents one of the magnetizers MC.

[0070] The magnetizer MC includes the magnet 10A and a magnetic shield 20C. Also in the case of the magnetizer MC, the magnetic shield 20C is formed by integral molding with the magnet 10A, and the magnetic shield 20C is thus in close contact with the magnet 10A.

[0071] The magnetic shield 20C of the magnetizer MC has a shape in which its side magnetic shield portions, provided on the two end surfaces in the moving direction of the magnet 10A, are tapered when viewed in the Y-axis direction. The side magnetic shield portions provided on the two end surfaces of the magnet 10A each have a shape in which an end portion closer to the opposing surface of the inner surface of each of the side magnetic shield portions is longer than an end portion closer to the opposing surface of the outer surface opposite to the inner surface of each of the side magnetic shield portions in a direction from the top surface to the opposing surface of the magnet 10A (that is, in the negative Z-axis direction).Accordingly, the surface connecting between the end portions closer to the opposing surface of each pair of one of the inner surfaces and a corresponding one of the outer surfaces is an inclined surface. In other words, due to the shape of each of the side magnetic shield portions tapered such that the surface on the side closer to the opposing surface of the magnet 10A is inclined, front end portions 63 and 64 of the side magnetic shield portions of the magnetic shield 20C in the negative Z direction each have a width in the X-axis direction (i.e., a width in the moving direction) that gradually decreases in a direction from the upper surface of the magnet 10A to the opposing surface of the magnet 10A.That is, the front end portions 63 and 64 of the side magnetic shield sections in the negative Z direction each have a width that gradually decreases in a direction from the positive Z direction to the negative Z direction. The taper angle of the magnetic shield 20C is a taper angle that can provide a desired magnetic flux density waveform.

[0072] As described above, the front end portions 63 and 64 of the magnetic shield 20C in the negative Z direction each have a shape in which the width of the magnetic shield 20C in the X direction gradually decreases in a direction toward the magnetic detection elements 30. The tapered structure in which the width of each of the front end portions 63 and 64 of the magnetic shield 20C in the negative Z direction gradually decreases in the direction toward the magnetic detection elements 30 is difficult to form using the methods M1 and M2 described above.

[0073] As described above, in the third embodiment, bringing the magnet 10A and the magnetic shield 20C having a tapered shape into close contact with each other enables the magnetic flux density waveform to have a desired shape.

[0074] The configurations described in the above embodiments are merely examples. These configurations may be combined with other known technologies, and configurations of different embodiments may be combined with each other. Furthermore, such configurations may be partially omitted and / or modified without deviating from the essence.

[0075] The above first embodiment was described in which the magnet 10A and the magnetic shield 20A are manufactured by integral molding to manufacture the linear transfer device 1. However, the magnet 10A and the magnetic shield 20A may be manufactured using a means other than integral molding. For example, a method for manufacturing the linear transfer device 1 includes cutting out a magnetic body that will serve as the magnet 10A and a magnetic body that will serve as the magnetic shield 20A with high accuracy from a single block of magnetic material using high-precision processing such as laser processing.This method of manufacturing the linear transport device 1 further includes magnetizing the cut-out magnetic body to serve as the magnet to produce the magnet 10A, and assembling the cut-out magnetic shield 20A and the magnet 10A to form the magnetizer MA. This method of manufacturing the linear transport device 1 further includes subsequently assembling the support devices 2, each including the magnetizer MA, and calculating a set of correction values ​​(i.e., a signal correction value, a position correction value, and / or the like) for the set of N support devices 2. The linear transport device 1 can then be manufactured by storing the calculated correction values ​​in the correction value memory 41 of the linear transport device 1.

[0076] A linear transport device 1 manufactured by such a manufacturing method can also reduce the variation between individual components in the dimension of the magnetic shield 20A and in the positional relationship of the magnetic shield 20A relative to the magnet 10A, and can thus prevent the occurrence of irregularities in the magnetic flux or magnetic lines of force. Such a linear transport device 1 can also prevent variation in the shape accuracy between the magnetizers MA, thereby enabling the linear transport device 1 to correct the position of one of the support devices 2 by applying a set of correction values ​​to one of the support devices 2, which set of correction values ​​is commonly applicable to another of the support devices 2.This can prevent an increase in the cost of the linear transport device 1 and the manufacturing cost of the linear transport device 1 and can also easily prevent a reduction in the accuracy of position detection. List of reference symbols 1 linear transport device; 2, 2-1 to 2-n carrier device; 4 Stator; 5 transport rail; 10A, 10B magnet; 20A-20C magnetic shielding; 30 magnetic detection element; 40 computing device; 41 correction value memory; 50 servo amplifiers; 61, 62 two end faces; 63, 64 front end section; MA-MC magnetizer; mV runner. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 7 046 290

[0004]

Claims

[1] Linear transport device, comprising: a transport path comprising a stator; a plurality of transport bodies configured to move along the transport path; a magnetizer installed on each of the transport bodies and configured to generate a magnetic field to be used in position detection; a magnetic detection element installed on the transport path and configured to detect the magnetic field; a computing device configured to calculate a position of each of the transport bodies based on the magnetic field detected by the magnetic detection element; and a correction value memory configured to store a correction value set which is a combination of correction values ​​for correcting the position of each of the transport bodies, wherein the magnetizer includes: a magnet in which magnetic poles of different polarities are arranged alternately along a direction of movement of the transport bodies; and a magnetic shield which is a magnetic body and is formed of a resin containing a magnetic material powder, the magnetic shield blocking magnetic lines of force emanating from the magnet by being provided in the moving direction on two end surfaces of the magnet and on an upper surface of the magnet, the upper surface being a surface opposite a counter surface facing the transport path, a number of the correction value set is smaller than a number of transport bodies, and the computing device is designed to correct the position of one of the transport bodies using the correction value set that is common to another transport body. [2] A linear transport device according to claim 1, wherein the magnet and the magnetic shield are formed by integral molding. [3] Linear transport device according to claim 1, wherein the number of the correction value set is one, and the computing device is designed to correct the positions of all transport bodies using a common set of correction values. [4] The linear transport device according to claim 1 or 2, wherein an angled portion on an upper side of the magnet is in close contact with a corner portion of an inner wall surface of the magnet shield, the corner portion being in contact with the angled portion. [5] The linear transport device according to any one of claims 1 to 3, wherein the correction value is a signal correction value for correcting a signal representing a magnetic flux density detected by the magnetic detection element. [6] The linear transport device according to any one of claims 1 to 3, wherein the correction value is a position correction value for correcting the position itself of each of the transport bodies, which is calculated from a signal representing a magnetic flux density detected by the magnetic detection element. [7] A linear transport device according to claim 2, wherein the integral molding causes the magnetic shield and the magnet to firmly hold each other. [8] Linear transport device according to one of claims 1 to 6, wherein the magnet is bevelled such that the two end faces are inclined in the direction of movement to cause the magnet to have a width in the direction of movement which decreases in a direction from the upper surface to the counter surface, Portions of the magnetic shield provided on the respective two end surfaces of the magnet are inversely tapered such that inner wall surfaces are inclined in the direction of movement to cause these portions of the magnetic shield to each have the width in the direction of movement which increases in the direction from the upper surface to the counter surface, and the two end faces of the magnet are in close contact with the inner wall surfaces of the magnetic shield in the direction of movement. [9] A linear transport device according to any one of claims 1 to 6, wherein portions of the magnetic shield provided on the respective two end surfaces of the magnet are formed such that, in the direction from the upper surface to the opposing surface, an end portion closer to the opposing surface of each of the inner surfaces in the moving direction is longer than the end portion closer to the opposing surface of each of the outer surfaces opposite to the respective inner surfaces in the moving direction, and a surface connecting between the end portions closer to the opposing surface of each pair of one of the inner surfaces and a corresponding one of the outer surfaces is an inclined surface. [10] Method for manufacturing the linear transport device according to one of claims 1 to 9, comprising: a molding step of forming the magnet and the magnetic shield by integral molding; and a correction value storage step of storing the at least one correction value set in the correction value memory. [11] A method of manufacturing the linear transport device according to claim 10, wherein the molding step comprises: a first forming step of forming the magnet by casting a magnetic material into a first mold, and a second molding step of arranging the magnet in a second mold and forming the magnetic shield by pouring a resin of magnetic material into the second mold in the presence of the magnet. [12] A method of manufacturing the linear transport device according to claim 10, wherein the molding step comprises: a first molding step of forming the magnetic shield by pouring a resin of magnetic material into a first mold, and a second molding step of arranging the magnetic shield in a second mold and forming the magnet by pouring a magnetic material into the second mold in the presence of the magnetic shield.

Images