Linear transport device and method for manufacturing a linear transport device

Abstract

Linear transport device (1), comprising: a transport path (5) comprising a stator (4); several transport bodies (2) designed to move along the transport path (5); a magnetizer (MA; MB; MC) installed on each of the transport bodies (2) and configured to generate a magnetic field to be used for position detection; a magnetic detection element (30) which is installed on the transport path (5) and is designed to detect the magnetic field; a computing device (40) configured to calculate the position of each of the transport bodies (2) based on the magnetic field detected by the magnetic sensing element (30); and a correction value memory (41) configured to store a set of correction values ​​which is a combination of correction values ​​for correcting the position of each of the transport bodies (2), wherein The magnetizer (MA; MB; MC) includes: a magnet (10A; 10B) in which magnetic poles of different polarities are arranged alternately along a direction of movement of the transport bodies (2); and a magnetic shield (20A; 20B; 20C) which is a magnetic body and is formed from a resin containing a magnetic material powder, wherein the magnetic shield (20A; 20B; 20C) blocks magnetic field lines emanating from the magnet (10A; 10B) by being provided in the direction of movement on two end faces (61, 62) of the magnet (10A; 10B) and on an upper surface of the magnet (10A; 10B), wherein the upper surface is a surface opposite a counter surface facing the transport path (5), a number of the correction value set is less than a number of the transport bodies (2), and the computing device (40) is designed to correct the position using one of the at least one set of correction values ​​that is available: to correct a position of at least one transport body (2) of the transport bodies (2); and to correct the position of another of the transport bodies (2).

Description

Area

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

[0002] To precisely control the position of a runner, a linear transport system incorporates position detectors to determine the runner's position based on the magnetic energy of a magnet attached to the runner. In such a linear transport system, the presence of runners approaching each other causes magnetic interference between the magnets, reducing the accuracy of the position detection. Additionally, factors such as dimensional tolerances in the manufacturing process of the runners lead to variations in the position detection values ​​among the position detectors, further reducing the accuracy of the position detection.

[0003] The position detector described in patent literature 1 comprises a magnetic shield for suppressing magnetic interference between magnets of approaching runners, wherein the magnetic shield is provided at end sections in the direction of movement and on a rear surface of the position detection magnet contained in each of the runners. From patent literature 2 and 3, computing units for linear transport devices are known that perform a correction when controlling the position of the runners. Citation list of patent literature Patent literature 1: JP 7 046 290 B1 (DE 11 2021 007 621 T5 is a German family member of patent literature 1) Patent literature 2: EP 2 779 389 A1 Patent literature 3: US 2019 / 0 092 578 A1 Brief description of the invention Problem to be solved by the invention

[0004] However, the technology described above in patent literature 1 has difficulties in precisely shaping a corner section on an inner surface of the magnetic shield, where in the magnetic shield an inner surface facing the position sensing magnet of a rear magnetic shield section provided on the rear surface meets an inner surface facing the position sensing magnet of a lateral magnetic shield section provided on a side surface.This means that shaping the corner section into the shape of the magnet with high accuracy is difficult in both cases: when the magnetic shield is formed by bending a plate-shaped magnet body into a shape covering the back surface and two side surfaces of the magnet; and when 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. Due to dimensional tolerances, this can create a gap between the magnet and the magnetic shield, causing an irregularity in the magnetic flux or magnetic field lines. This presents a problem in the form of reduced position detection accuracy.

[0005] The present disclosure was made in view of the foregoing, and it is an object of the present disclosure to provide a linear transport device which is able to avoid a reduction in the accuracy of position detection. Means to solve the problem

[0006] To solve the problem and achieve the task described above, a linear transport device comprises the combination of features of independent claim 1. Preferred embodiments are found in the dependent claims.

[0007] A linear transporter of the present disclosure comprises: a transport path comprising a stator; several 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 for 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 comprises: a computing device.The magnetizer comprises: a calculator configured to calculate the position of each of the transport bodies based on the magnetic field detected by the magnetic sensing element; and a correction value memory configured to store a set of correction values, which 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 arranged alternately along a direction of movement of the transport bodies; and a magnetic shield, which is a magnetic body formed from a resin containing a magnetic material powder, wherein the magnetic shield blocks magnetic field lines emanating from the magnet by forming two end faces in the direction of movement.The correction device is provided on the 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 less 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 the advantage of avoiding a reduction in accuracy in position detection. Brief description of the drawings Fig. Figure 1 is a perspective view showing a configuration of a linear transport device according to a first embodiment. Fig. Figure 2 is a side view showing a configuration of a magnetizer included in the linear transport device according to the first embodiment. Fig. Figure 3 is a block diagram illustrating the configuration of the linear transport device according to the first embodiment. Fig. Figure 4 is a flowchart that illustrates a process flow for manufacturing the linear transport device according to the first embodiment. Fig. Figure 5 is a side view showing a configuration of a magnetizer included in the linear transport device according to a second embodiment. Fig. Figure 6 is a side view showing 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 are described in detail below with reference to the drawings. First embodiment

[0010] Fig. Figure 1 is a perspective view showing a configuration of a linear transport device according to a first embodiment. Fig. Figure 2 is a side view showing a configuration of a magnetizer included in the linear transport device according to the first embodiment. In the Fig. 1 and Fig. Figure 2 shows two mutually perpendicular axes in a plane parallel to the top surface of magnet 10A, represented as the X-axis and 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 top surface of 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 carrier unit 2 comprises: a runner mV, which generates a magnetic field for propulsion; and a magnetizer MA, which generates a magnetic field to be used for position detection. The runner mV and the magnetizer MA are arranged in a lower section of each of the carrier units 2. It is noted that the carrier units 2 are an example of transport bodies. The transport bodies may further comprise one additional component besides the runner mV and the magnetizer MA contained in each of the carrier units 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 rotor mV is positioned so that it faces the stator 4. In the linear transport device 1, a movement of the rotor mV above the stator 4 causes the corresponding support device 2 above the transport rail 5 to move in the transport direction.

[0014] The stator 4, which generates a magnetic field for driving, and the magnetic sensing elements 30, which detect the positions of the carrier devices 2, are arranged on the transport rail 5. In the linear transport device 1, the rotor mV and the stator 4 form a linear motor. One of the rotor mV and the stator 4 can be designed using an electromagnet, and the other can be designed using either an electromagnet or a permanent magnet. It should be noted that the transport rail 5 is an example of a transport path. The transport path can additionally include further components, as long as it includes the stator 4 and the magnetic sensing elements 30 in addition to the transport rail 5.

[0015] The magnetic sensing 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 sensing elements 30 forms a position detector for the linear transport device. In the linear transport device 1, the runner 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 runner mV above the stator 4 causes the magnetizer MA to move above the magnetic sensing elements 30 when the carrier device 2 moves along the transport rail 5.

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

[0017] The magnetic field of magnet 10A is alternately directed in different directions along the direction of movement of the carrier device 2. That is, magnet 10A comprises several magnetic poles formed within a single magnetic body arranged along the direction of movement of the carrier device 2. It should be noted that magnet 10A can be formed from multiple magnets arranged along the direction of movement. Magnet 10A has a rectangular parallelepiped shape. Fig. Figure 2 represents a side surface of the side surfaces of magnet 10A, which has a rectangular parallelepiped shape. The magnet 10A is arranged in the carrier device 2 such that it encompasses the multiple magnetic poles, which are arranged along a direction corresponding to the direction of movement of the carrier device 2.

[0018] In Fig. 2. The solid arrows 7 indicate the magnetic field generated by magnet 10A. Furthermore, the arrows 11, shown as outlines, indicate the position of magnet 10A within the magnet. Fig. 2 each the direction of the magnetic field in the magnet 10A.

[0019] The magnetic shielding 20A comprises: lateral magnetic shielding sections provided on two end faces of the magnet 10A in its direction of movement (i.e., the front face and the rear face in the direction of movement); and a top magnetic shielding section provided on a top face of the magnet 10A, the face of which is a counter-face facing the transport rail 5. Perpendicular lines from the front face and from the rear face of the magnetizer MA in the direction of movement are parallel to the direction of movement.

[0020] The end faces of magnet 10A, on which the lateral magnetic shielding sections are provided, are the front and rear faces of magnet 10A. The face of magnet 10A on which the top magnetic shielding section is provided is the upper face opposite the mating face facing the transport rail 5. This configuration allows the magnetic shield 20A to be designed such that the lateral magnetic shielding sections and the top magnetic shielding section are connected to each other in the Y-axis direction, thus forming a shape to cover both end faces and the top face of magnet 10A.

[0021] It should be noted that the upper surface of magnet 10A, which is in close contact with the upper magnetic shielding section, can also be considered the rear surface (rear surface section) of magnet 10A when viewed from transport rail 5. Furthermore, the inner wall surface of the upper magnetic shielding section, which is in close contact with magnet 10A, can also be considered the lower surface of magnetic shielding 20A when viewed from transport rail 5.

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

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

[0024] The outer surface of magnet 10A, which has a rectangular parallelepiped shape, has its front, back, and top surfaces in close contact with the inner surface of the magnetic shield 20A. That is, the angled section formed by the top and front surfaces of magnet 10A, and the angled section formed by the top and back surfaces of magnet 10A, are covered by the inner surface of the magnetic shield 20A. It should be noted that the angled section formed by the top and front surfaces of magnet 10A, and the angled section formed by the top and back surfaces of magnet 10A, are angled sections on the upper side of magnet 10A.As described above, the linear transport device 1 is designed such that the corner sections of the inner wall surface of the magnetic shield 20A, which are in contact with the respective angled sections on an upper side of the magnet 10A, are in close contact with the respective angled sections on an upper side of the magnet 10A, leaving no space between the magnetic shield 20A and the magnet 10A. It should be noted that the inner wall surface of the magnetic shield 20A can cover the two side surfaces, unlike the front and rear surfaces of the outer wall surface of the magnet 10A, which has a rectangular parallelepiped shape.

[0025] The magnetic shield 20A is formed from a material having a magnetic permeability greater than 1, such as iron. In particular, the magnetic shield 20A is formed from a resin containing a magnetic material powder. In the first embodiment, the magnetic shield 20A, which includes a section for blocking magnetic energy, 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 between them. This configuration causes the magnetic shield 20A and the magnet 10A to hold each other firmly. That is, the magnetic shield 20A holds the magnet 10A firmly, and the magnet 10A holds the magnetic shield 20A firmly.

[0026] During the integral forming process in the first embodiment, the magnet 10A is first formed, for example, by 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 resin (i.e., for the magnetic shield 20A), and the magnetic resin is poured into the mold for the magnetic resin. The mold for the magnetic resin has a cavity in one section for forming the magnetic shield 20A and in another section for placing the magnet 10A.With respect to this cavity section, the magnet 10A is positioned in the section for arranging the magnet 10A, and the resin made of magnetic material is poured into the section for forming the magnetic shield 20A, causing the magnetic shield 20A to be formed integrally with the magnet 10A.

[0027] It should be noted that during integral molding in the first embodiment, the magnetic shield 20A can be formed first. In this case, the magnetic shield 20A is first formed by injection molding using the mold for the magnetic shield 20A. That is, the magnetic resin is poured into the mold for the magnetic resin, and the magnetic shield 20A is thus formed. Then, the magnetic shield 20A is placed 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 one section for forming the magnet 10A and in another section for placing the magnetic shield 20A.With respect to this cavity section, the magnetic shield 20A is arranged in the section for arranging the magnetic shield 20A, and the magnetic material is poured into the section for forming the magnet 10A, causing the magnet 10A to be formed integrally with the magnetic shield 20A.

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

[0029] The magnetic sensing element 30 detects the magnetic field generated by the magnet 10A. Specifically, the magnetic sensing element 30 converts the displacement of the magnetic field generated by the magnet 10A into a change in signal output. An example of the magnetic sensing element 30 is a Hall effect sensor. The magnetic sensing element 30 sends information about the detected magnetic field to the computing unit 40. The multiple magnetic sensing elements 30 are installed on the transport rail 5 along the direction of movement of the magnetizer MA. The magnetic field detected by each of the magnetic sensing elements 30 varies as the magnetizer MA moves.

[0030] The computing unit 40 calculates the position (position data) of the carrier unit 2 (magnetizer MA) based on a measured value of the magnetic flux (e.g., the magnetic flux density) transmitted by the magnetic sensing element 30. The position of the carrier unit 2 corresponds to the position of the magnet 10A and the position of the rotor mV. The computing unit 40 transmits the position data with respect to the carrier unit 2 to the servo amplifier 50.

[0031] Fig. Figure 3 is a block diagram representing a configuration of the linear transport device according to the first embodiment. The linear transport device 1 comprises several 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 defined with reference to Fig. 2 described carrier devices 2 similar carrier devices. In the description of the first embodiment, the carrier devices 2-1 to 2-n can be referred to as carrier devices 2 if no distinction needs to be made between the carrier devices 2-1 to 2-n. The carrier devices 2-1 to 2-n each comprise the magnets 10A, which have the same 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 each 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 sends information regarding the detected magnetic field to the computer 40.

[0033] The computing unit 40 includes a correction value memory 41. The correction value memory 41 stores a correction value in advance for correcting the positions of the support units 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. It should be noted that the correction value memory 41 can be located outside the computing unit 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 in which 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, if the magnetic flux density of magnet 10A of each carrier device 2-1 to 2-n, detected by the magnetic sensing 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 devices 2-1 to 2-n. The computing unit 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. If B denotes the magnetic flux density of magnet 10A of each carrier device 2-1 to 2-n, this magnetic flux density is represented, for example, as B = Psinθ + 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 unit 40 corrects the signal representing the magnetic flux density transmitted by each of the magnetic sensing elements 30 using the signal correction values ​​stored in the correction value memory 41. The computing unit 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 unit 40 transmits the position data with respect to the carrier devices 2-1 to 2-n to the servo amplifier 50.

[0037] The signal correction values ​​pre-stored in the correction value memory 41 are values ​​common to the carrier devices 2-1 to 2-n. It should be noted that it is sufficient for signal correction values ​​that are common to at least two of the carrier devices 2-1 to 2-n to be used in the linear transport device 1. That is, it is sufficient for the number of sets of signal correction values ​​(e.g., sets of correction values ​​for amplitude and correction values ​​for offset) to be pre-stored in the correction value memory 41 to be less than the number of carrier devices 2-1 to 2-n. In other words, it is sufficient for the number of correction value sets, each of which is a combination of correction values, to be less than the number of carrier devices 2-1 to 2-n. The following description describes a case in which there is (exactly) one correction value set.It should be noted that the correction values ​​contained in the correction value set may be of one type or of several types.

[0038] The servo amplifier 50 controls the linear motor based on the position data relative to the carrier unit 2. This control ensures that the electrical energy supplied to the stator 4 is adjusted to a level suitable for the position of the rotor. Adjusting the electrical energy supplied to the stator 4 allows for adjustments to the magnitudes of the magnetic fields generated by the rotor and the stator 4 for driving the motor, thereby adjusting the position of the rotor. In other words, the carrier unit 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, resulting in close contact between them without any space between them. Thus, the linear transport device 1 includes no space between the magnetic shield 20A and the magnet 10A, thereby preventing irregularities in the magnetic flux or magnetic field lines. This enables the linear transport device 1 to: detect similar sinusoidal signals from the respective carrier devices 2-1 to 2-n; and correct the sinusoidal signals using signal correction values ​​that are common to all carrier devices 2-1 to 2-n.

[0040] Furthermore, performing an integral forming process to create 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 field lines.

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

[0042] When a carrier device 2, which is not the target of the position detection, approaches the carrier device 2, which is the target of the position detection, the magnetic detection element 30 detects the magnetic field generated by the magnet 10A of the carrier device 2, provided that the carrier device 2, which is not the target of the position detection, does not include the magnetic shield 20A. In this case, the accuracy in detecting the position of the carrier 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 the accuracy of the position detection. This means that, since the linear transport device 1 includes the magnetic shield 20A, the magnetic force emanating from the magnet 10A of a support device 2 that is not the target of the position detection, which generates small loop-forming magnetic force lines, is blocked by the lateral magnetic shield sections and is thereby prevented from reaching the magnetic detection element 30.Furthermore, since the linear transport device 1 includes the magnetic shield 20A, the magnetic force, which generates large loop-forming magnetic force lines, emanating from a carrier device 2 that is not the target of position detection, is blocked by the upper magnetic shield section and is thereby prevented from reaching the magnetic detection element 30.

[0044] Apart from this, there is a method for forming the magnetic shield by bending a plate-shaped magnetic body (hereinafter referred to as method M1). Method M1 involves a bending radius (corner radius) that occurs in a bent section 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 section of the magnetic shield (i.e., the corner section of the inner surface of the magnetic shield facing the bent section of the magnet). Thus, method M1 creates an air gap between the magnet and the magnetic shield, causing an irregularity in the magnetic flux or magnetic field lines. Such an irregularity in the magnetic flux or magnetic field lines can lead to a variation in the position detection values ​​from the position detector.This reduces the accuracy in determining the position of a support device. Furthermore, method M1 has difficulties performing shallow bending. This requires the dimension of the lateral magnetic shielding sections to reach or exceed a certain value in the depth direction, which makes thickness reduction difficult.

[0045] Furthermore, there is a method for forming the magnetic shield by cutting a block of magnetic material into a right-angled U-shape (hereinafter referred to as method M2). Due to a manufacturing tolerance, method M2 cannot form the corner section of the base of the right-angled U-shaped section (i.e., the corner section of the inner surface of the magnetic shield facing the angled section of the magnet) to be at a right angle, leaving a curved or C-shaped surface in the corner section of the base of the right-angled U-shaped section. This prevents the magnet from coming into close contact with the corner section of the inner surface of the magnetic shield. Thus, method M2 creates an air gap between the magnet and the magnetic shield, causing an irregularity in the magnetic flux or magnetic field lines.Such an irregularity in the magnetic flux or magnetic field lines can lead to variations in the position detection values ​​from the position detector. This reduces the accuracy in detecting the position of a support device. Furthermore, the magnet block is made of a metal that is harder than aluminum or brass, making the machining process more time-consuming and expensive.

[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 (especially the magnetic shield), resulting in a variation in the magnetic fields generated by the respective carrier devices. Therefore, when carrier devices manufactured using either method M1 or M2 are used in the linear transport device, avoiding a reduction in the accuracy of the carrier device positions requires calculating signal correction values ​​on a per-carrier basis during an acceptance test and pre-storing these signal correction values ​​in the correction value memory.For example, if a single linear transport device carries 100 carrier units (N = 100), the correction value memory must pre-store signal correction values ​​for the magnets of the 100 carrier units, requiring a memory with very high capacity. Furthermore, determining signal correction values ​​for 100 magnets requires a long computation time and significant effort, increasing the manufacturing costs 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 casting a magnetic material and a resin made of magnetic material. This brings the magnet 10A and the magnetic shield 20A 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 any relative positional misalignment between the magnet 10A and the magnetic shield 20A. This eliminates any variation in the magnetic fields generated by the magnetizers MA, thereby preventing a reduction in accuracy in detecting the position of the magnet 10A of each of the carrier devices 2 for the linear transport device 1. Furthermore, in the first embodiment, the production of the resin mold (i.e.,the mold for the magnetic shield 20A), which is a mold for the resin made of magnetic material, reduces the manufacturing tolerance of the magnetic shield 20A with high accuracy.

[0048] As described above, in the first embodiment, the linear transport device 1 can prevent variations in the magnetic fields generated by the magnets 10A of the N carrier devices 2. Accordingly, storing a 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 lower the cost of the linear transport device 1. It can also reduce the time required to determine the signal correction values ​​and thus lower the manufacturing costs of the linear transport device 1.

[0049] Furthermore, in the first embodiment, the magnetic shield 20A is formed by integral forming with the magnet 10A using a resin containing a magnetic material powder (i.e., a resin with a magnetic material powder), which allows the magnet 10A to have a thickness that is less than the thickness achieved by 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. This allows the magnetic shield 20A and the magnet 10A to be brought into close contact with each other over all surfaces where they face each other, including the corner sections of the inner surface of the magnetic shield 20A, without any gap between them. Compared to using either method M1 or M2, this can increase the accuracy in detecting the position of the magnet 10A and can reduce costs by shortening the processing time in the first embodiment.

[0051] Furthermore, magnets and rotational angle sensors are in a one-to-one relationship when considering the case of a rotational angle sensing device for detecting the rotational 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 transport device 1 comprises the several (N) carrier devices 2, each containing the runner mV. This results in an N-to-one relationship (where N ≥ 2) among the magnets 10A used for position detection and the magnet sensing element 30. That is, each of the magnet sensing elements 30 detects the positions of the N magnets 10A. Thus, if the magnet 10A and the magnet shield 20A are subject to large manufacturing variation, this necessitates that N correction values ​​be pre-stored 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 it is therefore sufficient to store a single set of correction values ​​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. This reduces the variation between individual components in the dimensions 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 dimensional accuracy between the magnetizers MA and thus enables the linear transport device 1 to provide highly accurate positioning using a single type of correction value.

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

[0054] One (1) set of correction values ​​(i.e., 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] It should be noted that if M (where M is a natural number greater than or equal to 2) linear transport devices 1 are to be manufactured, M x N sets of magnets 10A and magnetic shields 20A formed by integral forming are produced. Then, for the M x N carrier devices 2, one (1) set of correction values ​​is calculated. The calculated correction value is stored in the correction value memory 41 of each of the linear transport devices 1.

[0056] As described above, the linear transport device 1 of the first embodiment comprises the magnetic shield 20A and the magnet 10A, which are formed by integral shaping, and the number of combinations of correction values ​​(i.e., sets of correction values) for correcting the positions of the carrier devices 2 is less than the number of carrier devices 2. Additionally, the linear transport device 1 corrects the position of one of the carrier devices 2 by applying a set of correction values ​​to that one of the carrier devices 2, which is also applicable to another of the carrier devices 2. This enables the linear transport device 1 to easily prevent a reduction in the accuracy of the position detection. Second embodiment

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

[0058] Fig. Figure 5 is a side view showing a configuration of a magnetizer included in the linear transport device according to the second embodiment. The same reference numerals are used to identify components of the components of Fig. 5 to identify those that provide the same functionality as the corresponding components of the linear transport device 1 of the in Fig. 2 first embodiment shown, and a duplicate description of these is 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 several carrier devices 2, wherein in Fig. 5 shows one of the magnetizers MB.

[0060] The magnetizer MB comprises a magnet 10B and a magnetic shield 20B. In the case of the magnetizer MB as well, the magnetic shield 20B is formed integrally with the magnet 10B, and the magnetic shield 20B is thus in close contact with the magnet 10B. Similar to the first embodiment, the magnet 10B has a counter surface facing the transport rail 5, an upper surface opposite the counter surface, two end faces, and two further side faces in the direction of movement.

[0061] The magnet 10B of the magnetizer MB is inclined in the Y-axis direction such that its two end faces 61 and 62 are inclined in the direction of movement of the magnetizer MB (direction of movement of the support devices 2). Because it is inclined, the magnet 10B has a width in the X-axis direction (i.e., a width in the direction of movement) that gradually decreases from the upper surface of the magnet 10B to the opposite surface. That is, the magnet 10B has a width that gradually decreases 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 lateral magnetic shielding sections, located on the two end faces 61 and 62 in the direction of motion of the magnet 10B, are inversely tapered in the Y-axis direction. Because it is inversely tapered such that the inner surfaces of the lateral magnetic shielding sections are inclined, the magnetic shield 20B has a width in the X-axis direction (i.e., a width in the direction of motion) that gradually increases in a direction from the upper surface of the magnet 10B to the opposite surface of the magnet 10B. That is, the lateral magnetic shielding sections each have a width that gradually increases in a direction from the positive Z-direction to the negative Z-direction. The inverse taper angle of the magnetic shield 20B is an inverse taper angle that can provide a desired magnetic flux density waveform.

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

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

[0065] As described above, in the second embodiment, the magnet 10B, which has a beveled shape, and the magnetic shield 20B are formed by integral shaping, thereby providing a structure in which the magnet 10B, which has a beveled shape, and the magnetic shield 20B, which has a reverse beveled shape, are in close contact with each other. Bringing the magnet 10B, which has a beveled shape, and the magnetic shield 20B, which has a reverse beveled shape, into close contact with each other allows the magnetic flux density waveform to have a desired shape.

[0066] Furthermore, the magnetizer MB is designed such that the upper surface of magnet 10B is larger than the opening provided between the lateral magnetic shielding sections of the magnetic shield 20B on the side closer to the opposite surface of magnet 10B. This prevents magnet 10B from detaching from the magnetic shield 20B when the magnetizer MB moves rapidly or along a curve. In other words, magnet 10B, which has a shape angled in the negative Z-direction, and the magnetic shield 20B, which has a shape angled in the opposite direction in the negative Z-direction, are in close contact with each other, and the magnetizer MB can therefore prevent magnet 10B from falling off. Third embodiment

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

[0068] Fig. Figure 6 is a side view showing a configuration of a magnetizer included in the linear transport device according to the third embodiment. The same reference numerals are used to identify components of the components of Fig. 6 to specify which have the same functionality as the functionality of the corresponding components of the linear transport device 1 of the in Fig. 2 provide the first embodiment shown, and a duplicate description of these is 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 several carrier devices 2, but Fig.6 represents one of the MC magnetizers.

[0070] The magnetizer MC comprises the magnet 10A and a magnetic shield 20C. In the case of the magnetizer MC as well, the magnetic shield 20C is formed by integral shaping 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 lateral magnetic shielding sections, provided on the two end faces in the direction of movement of the magnet 10A, are chamfered in the Y-axis direction. The lateral magnetic shielding sections provided on the two end faces of the magnet 10A each have a shape in which an end section closer to the opposing surface of the inner surface of each of the lateral magnetic shielding sections is longer than an end section closer to the opposing surface of the outer surface opposite the inner surface of each of the lateral magnetic shielding sections, in a direction from the upper surface to the opposing surface of the magnet 10A (i.e., in the negative Z-axis direction).Accordingly, the surface connecting the end sections of each pair of inner surfaces and a corresponding outer surface that are closer to the opposite surface is an inclined surface. In other words, due to the shape being inclined such that the surface on the side closer to the opposite surface of magnet 10A is inclined, the front end sections 63 and 64 of the side magnet shield sections of magnet shield 20C each have a width in the X-axis direction (i.e., a width in the direction of motion) in the negative Z-direction that gradually decreases in a direction from the upper surface of magnet 10A to the opposite surface of magnet 10A.This means that the front end sections 63 and 64 of the lateral magnetic shielding sections in the negative Z-direction each have a width that gradually decreases in one 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 sections 63 and 64 of the magnetic shield 20C each have a shape in the negative Z direction in which the width of the magnetic shield 20C gradually decreases in the X direction towards the magnetic detection elements 30. The chamfered structure, in which the width of each of the front end sections 63 and 64 of the magnetic shield 20C gradually decreases in the negative Z direction towards the magnetic detection elements 30, is difficult to form using the methods M1 and M2 described above.

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

[0074] The configurations described in the preceding embodiments are merely examples. These configurations can be combined with other known technologies, and configurations of different embodiments can be combined with one another. Furthermore, such configurations can be partially omitted and / or modified without deviating from the core principle.

[0075] The foregoing first embodiment has been described in which the magnet 10A and the magnetic shield 20A are produced by integral forming to manufacture the linear transport device 1. However, the magnet 10A and the magnetic shield 20A can be produced by means other than integral forming. For example, one method for manufacturing the linear transport device 1 comprises cutting a magnetic body, which will serve as the magnet 10A, and a magnetic body, which will serve as the magnetic shield 20A, with high precision from a single block of magnetic material using high-precision processing, such as laser processing.This method for manufacturing the linear transport device 1 further comprises magnetizing the cut-out magnetic body to serve as the magnet for manufacturing the magnet 10A, and joining the cut-out magnetic shield 20A and the magnet 10A to form the magnetizer MA. This method for manufacturing the linear transport device 1 further comprises subsequently assembling the carrier devices 2, each comprising 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 carrier 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 process can also reduce the variation between individual components in the dimensions 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 in the magnetic field lines. Such a linear transport device 1 can also prevent variations in the dimensional accuracy between the magnetizers MA, thereby enabling the linear transport device 1 to correct the position of one of the carrier devices 2 by applying a set of correction values ​​to that one of the carrier devices 2, which set of correction values ​​can be applied to another of the carrier devices 2.This can prevent an increase in the cost of the linear transport device 1 and the manufacturing costs of the linear transport device 1, and can also easily prevent a reduction in the accuracy of the position detection. Reference symbol list 1 Linear transport device; 2, 2-1 to 2-n carrier institution; 4 Stator; 5 Transport rail; 10A, 10B Magnet; 20A-20C Magnetic shielding; 30 magnetic detection elements; 40 computer equipment; 41 Correction value memory; 50 servo amplifiers; 61, 62 two end faces; 63, 64 front end section; MA-MC Magnetizer; mV runner.

Claims

Linear transport device (1) comprising: a transport path (5) comprising a stator (4); several transport bodies (2) configured to move along the transport path (5); a magnetizer (MA; MB; MC) installed on each of the transport bodies (2) configured to generate a magnetic field to be used for position detection; a magnetic detection element (30) installed on the transport path (5) configured to detect the magnetic field; a computing device (40) configured to calculate a position of each of the transport bodies (2) based on the magnetic field detected by the magnetic detection element (30); and a correction value memory (41) configured to store a set of correction values ​​that is a combination of correction values ​​for correcting the position of each of the transport bodies (2), wherein the magnetizer (MA; MB; MC) comprises: a magnet (10A;10B), in which magnetic poles of different polarities are arranged alternately along a direction of movement of the transport bodies (2); and a magnetic shield (20A; 20B; 20C), which is a magnetic body and is formed from a resin containing a magnetic material powder, wherein the magnetic shield (20A; 20B; 20C) blocks magnetic force lines emanating from the magnet (10A; 10B) by acting in the direction of movement on two end faces (61, 62) of the magnet (10A; 10B) and on an upper face of the magnet (10A;10B) is provided, wherein the upper surface is a surface opposite a counter surface facing the transport path (5), a number of correction value sets is less than a number of transport bodies (2), and the computing device (40) is configured to correct the position using one of the at least one correction value set, which is usable: for correcting a position of at least one transport body (2) of the transport bodies (2); and for correcting a position of another of the transport bodies (2). Linear transport device (1) according to claim 1, wherein the magnet (10A; 10B) and the magnetic shield (20A; 20B; 20C) are formed by integral forming. Linear transport device (1) according to claim 1, wherein the number of correction value sets is one, and the computing device (40) is configured to correct the positions of all transport bodies (2) using a common correction value set. Linear transport device (1) according to claim 1 or 2, wherein an angled section on an upper side of the magnet (10A; 10B) is in close contact with a corner section of an inner wall surface of the magnet shield (20A; 20B; 20C), wherein the corner section is in contact with the angled section. Linear transport device (1) according to 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 sensing element (30). Linear transport device (1) according to 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 (2) which is calculated from a signal representing a magnetic flux density detected by the magnetic sensing element (30). Linear transport device (1) according to claim 2, wherein the integral forming causes the magnetic shield (20A; 20B; 20C) and the magnet (10A; 10B) to hold each other firmly. Linear transport device (1) according to one of claims 1 to 6, wherein the magnet (10B) is inclined such that the two end faces (61, 62) are inclined in the direction of movement to cause the magnet (10B) to have a width in the direction of movement which decreases in a direction from the upper surface to the opposite surface, sections of the magnetic shield (20B) provided on the respective two end faces (61, 62) of the magnet (10B) are inclined in the opposite direction such that inner wall surfaces are inclined in the direction of movement to cause these sections of the magnetic shield (20B) to each have a width in the direction of movement which increases in the direction from the upper surface to the opposite surface, and the two end faces (61, 62) of the magnet (10B) are each in close contact with the inner wall surfaces of the magnetic shield (20B) in the direction of movement. Linear transport device (1) according to one of claims 1 to 6, wherein sections of the magnetic shielding (20C) provided on the respective two end faces (61, 62) of the magnet (10A) are designed such that, in the direction from the upper surface to the opposite surface, an end section of each of the inner surfaces that is closer to the opposite surface is longer in the direction of movement than the end section of each of the outer surfaces that is closer to the opposite surface, which is opposite the respective inner surfaces in the direction of movement, and a surface connecting the end sections that are closer to the opposite surface of each pair of one of the inner surfaces and a corresponding outer surface is an inclined surface. Method for manufacturing the linear transport device (1) according to any one of claims 1 to 9, comprising: a forming step of forming the magnet (10A; 10B) and the magnetic shield (20A; 20B; 20C) by integral forming; and a correction value storage step of storing the at least one set of correction values ​​in the correction value storage (41). Method for manufacturing the linear transport device (1) according to claim 10, wherein the forming step comprises: a first forming step of forming the magnet (10A; 10B) by casting a magnetic material into a first mold, and a second forming step of arranging the magnet (10A; 10B) in a second mold and forming the magnetic shield (20A; 20B; 20C) by casting a resin made of magnetic material into the second mold in the presence of the magnet (10A; 10B). Method for manufacturing the linear transport device (1) according to claim 10, wherein the forming step comprises: a first forming step of forming the magnetic shield (20A; 20B; 20C) by casting a resin of magnetic material into a first mold, and a second forming step of arranging the magnetic shield (20A; 20B; 20C) in a second mold and forming the magnet (10A; 10B) by casting a magnetic material into the second mold in the presence of the magnetic shield (20A; 20B; 20C).

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