JP7351992B1 - position detection device - Google Patents

Abstract

An object of the present invention is to provide a position detection device that easily protects a scale from foreign objects. [Solution] A position detection device in one aspect includes a rail that guides a movable body and has a recess extending in the direction of guiding the movable body, and a magnetized pattern is formed on a coated magnetic material. A scale is placed in a concave area extending from the top, a cover is placed on the rail to cover the scale, and a magnetic sensor for detecting the position of a moving object has a sensor head placed opposite the scale with the cover in between. A magnetic sensor having a magnetic sensor. When viewed in a direction intersecting the direction in which the scale extends, the cover is welded into a rectangular shape that surrounds the scale and is fixed to the rail, and the four corners of the rectangular shape are formed by welding. [Selection diagram] Figure 7

Description

The present invention relates to a position detection device for detecting the position of a moving body, and more particularly to a structure for fixing a scale to a rail that guides the moving body.

The main spindle and table of a machine tool are controlled to move to a target position by driving a saddle that supports them along a guide rail. In order to realize this movement control with high precision, some bicycles have a position detection device disposed between the saddle and the guide rail (see Patent Document 1). Such a position detection device includes a magnetic sensor provided on the saddle side and a scale provided on the guide rail side. By measuring the relative position with a magnetic sensor to the scale, the position of the main axis, etc. can be detected.

A magnetized pattern made of magnetic material is recorded on the scale. The magnetic sensor is provided with a detection head for reading the magnetic field of the magnetized pattern. The detection head is composed of a sensor such as an MR element (Magneto Resistive Sensor) that can detect the direction and strength of a magnetic field. The detection head detects the magnetized pattern and converts the detected value into an electrical signal, making it possible to measure positions in micrometers.

JP2019-35641A

In the machining chamber of a machine tool, foreign substances such as particles of cutting chips and coolant for lubrication are scattered. If these foreign substances adhere to the scale, there is a possibility that highly accurate detection by the magnetic sensor will be inhibited. Therefore, when installing the scale on the guide rail, it is necessary to adopt a structure that is not easily affected by such foreign substances. Note that such a problem is not limited to machine tools, and can occur in any position detection device configured by disposing a scale on a guide rail of a moving body.

A position detection device according to an aspect of the present invention includes a rail that guides a movable body and has a recess extending in the direction of guiding the movable body, and a magnetized pattern is formed on a coated magnetic material. A scale placed in an extending recess, a cover placed on a rail to cover the scale, and a magnetic sensor for detecting the position of a moving object, with a sensor head placed opposite the scale across the cover. A magnetic sensor. When viewed in a direction intersecting the direction in which the scale extends, the cover is welded into a rectangular shape that surrounds the scale and is fixed to the rail, and the four corners of the rectangular shape are formed by welding.

A position detection device according to another aspect of the present invention includes a rail that guides a movable body and has a concave portion extending in the direction of guiding the movable body, and a magnetic body on which a pattern is formed, and that extends along the rail. A scale placed in a concave part, a cover placed on a rail to cover the scale, and a magnetic sensor for detecting the position of a moving object, which has a sensor head at a position facing the scale with the cover in between. A magnetic sensor. The cover is welded to a rectangular shape that surrounds the scale when viewed in a direction crossing the direction in which the scale extends and is fixed to the rail. The rail has a hole, a first end of the hole in the recess, a first end of the hole outside the recess, and a second end at the opposite end. When viewed in a second direction intersecting the first direction in which the scale extends, the first end portion and the scale are arranged in the recessed portion side by side without overlapping in the first direction.

According to the present invention, it is possible to provide a position detection device that easily protects a scale from foreign objects.

FIG. 1 is a perspective view showing the appearance of a position detection device according to an embodiment. FIG. 3 is a diagram illustrating a partially disassembled state of the sensor unit. 3 is a sectional view taken along the line AA in FIG. 2. FIG. FIG. 3 is a perspective view showing a structure for assembling the scale to the rail. FIG. 3 is a perspective view showing a structure for assembling the scale to the rail. 6 is a cross-sectional view of the rail shown in FIG. 5. FIG. It is a figure showing the welding method of the cover to a rail. FIG. 2 is a diagram schematically representing a welding method employed in this embodiment. FIG. 2 is a diagram schematically representing a welding method employed in this embodiment. It is a figure showing typically the welding method concerning a modification.

Embodiments of the present invention will be described in detail below with reference to the drawings. For convenience of explanation, the X-axis and Y-axis are set in the horizontal direction, and the Z-axis is set in the vertical direction, and the positional relationship of each structure may be expressed based on the illustrated state. Further, in the following embodiments and modifications thereof, substantially the same components are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

FIG. 1 is a perspective view showing the appearance of a position detection device according to an embodiment.
The position detection device 1 includes a metal rail 4 that guides the movement of the movable body 2, a scale 6 disposed on the rail 4, and a sensor unit 8 provided integrally with the movable body 2. In this embodiment, the position detection device 1 detects the position of a movement control target in a machine tool. The movement controlled objects include, for example, the spindle and the table.

The rail 4 has a long shape and is installed in a machine tool to constitute a drive mechanism. A saddle (not shown) of a machine tool is fixed to the movable body 2, and the saddle supports the object to be controlled. In the illustrated example, one moving body 2 is arranged on the rail 4, but a plurality of moving bodies 2 may be arranged in series along the rail 4 to support the saddle. Here, the longitudinal direction of the rail 4 is the X direction, the width direction is the Y direction, and the height direction is the Z direction.

A sensor unit 8 is provided at one end of the moving body 2 in the X direction. The sensor unit 8 includes a holder 9 fixed to the moving body 2 and a magnetic sensor 10 assembled to the holder 9. The moving body 2 and the holder 9 are provided so as to straddle the rail 4 in the width direction (Y direction). A magnetic sensor 10 is arranged on one side of the holder 9 in the width direction. A cable 12 extends from the magnetic sensor 10 for extracting a detection signal.

The rail 4 has a tapered cutout (V-shaped cross section) on both sides, and the tapered surfaces constitute upper and lower guide surfaces 14a and 14b (if these are not particularly distinguished, (simply referred to as "guide surface 14"). On the other hand, although not shown, a plurality of rolling elements such as rollers or balls are arranged on the inner surface of the moving body 2. The moving body 2 moves in the longitudinal direction of the rail 4 while its rolling elements roll along the guide surface 14.

A recess 18 is provided on the bottom surface 16 of one side of the rail 4 (the surface that becomes the base end of the upper and lower tapered surfaces). The recess 18 is provided so as to extend along the rail 4 (details will be described later). Then, the scale 6 is arranged so as to fit into the recess 18. Furthermore, by assembling the cover 20 to the rail 4 so as to cover the scale 6, protection of the scale 6 and prevention of contamination are realized. The structure of scale 6 and its surroundings will be described in detail later.

A plurality of screw holes 22 passing vertically through the rail 4 are provided at predetermined intervals in the longitudinal direction of the rail 4. The rail 4 is fixed at a predetermined position in the machine tool by inserting bolts into these screw holes.

FIG. 2 is a diagram showing a partially disassembled state of the sensor unit 8.
A scraper unit 24 is provided on the end surface of the holder 9 opposite to the movable body 2, and a cover 26 is assembled to cover the scraper unit 24 from the outside. Cover 26 is fixed to holder 9 with screws 27. The scraper unit 24 has a laminated structure in which three scrapers 28a to 28c are piled up (unless they are particularly distinguished, they are simply referred to as "scrapers 28").

The scraper 28 is made of a flexible member such as rubber, and has a contact surface that comes into contact with the surface of the cover 20. The scraper unit 24 prevents foreign matter attached to the surface of the cover 20 from entering the holder 9 as the movable body 2 moves. Additionally, foreign matter adhering to the surface of the cover 20 is removed as the movable body 2 moves.

FIG. 3 is a cross-sectional view taken along the line AA in FIG.
The magnetic sensor 10 has a sensor head 30 at a position facing the scale 6 with the cover 20 in between. Sensor head 30 includes an MR element. The sensor head 30 may be constructed by sealing an MR element mounted on a substrate with resin to prevent contamination by coolant or the like. The magnetic sensor 10 is assembled to the holder 9 using screws (not shown), so that the magnetic sensor 10 is disposed facing the scale 6.

4 and 5 are perspective views showing a structure for assembling the scale 6 to the rail 4. FIG. 4 is an exploded view, and FIG. 5 is an assembled view. In each figure, for convenience of explanation, the structural elements shown in FIG. 1 are shown briefly in the longitudinal direction of the rail 4.

As shown in FIG. 4, a recess 18 is provided on one side (bottom surface 16) of the rail 4. The recess 18 extends in the longitudinal direction of the rail 4 (that is, the direction in which the movable body 2 is guided) and has a stepped shape in the longitudinal direction. A portion closer to the center in the longitudinal direction of the recess 18 is the lowest position (deepest position) on the bottom surface 16, and constitutes a mounting portion 32 for the scale 6. Further, a support portion 34 made of a protrusion is provided at the center position in the width direction of the recess 18 and extends in the longitudinal direction of the rail 4.

The support section 34 has a first support section 36 that supports the scale 6 and a second support section 38 that supports the cover 20. The second support portions 38 are provided on both sides of the first support portion 36 in the longitudinal direction of the rail 4. The first support portion 36 and the second support portion 38 have different heights on the bottom surface 16 and are connected via a tapered slope 40.

At both ends of the rail 4, holes 42a and 42b (simply referred to as "holes 42" unless otherwise distinguished) are provided for supplying air to the recess 18, respectively. One end (first end 44a) of the hole 42 opens on the side surface of the rail 4, and the other end (second end 44b) opens on the top surface of the rail 4. Details of this air supply will be described later.

A magnetic material is applied to the surface of the scale 6, and a magnetized pattern of N and S poles is formed. Note that this magnetic material can be obtained by dissolving magnetic powder and polyvinyl chloride (PVC) in a solvent. Although not shown, an absolute pattern is formed at the center of the scale 6 in the width direction (Z direction) as a magnetized pattern, and incremental patterns are formed on both sides of the absolute pattern in the width direction. The scale 6 is attached to fit into the attachment portion 32.

The cover 20 is a rectangular plate-shaped member made of non-magnetic metal (for example, stainless steel). The cover 20 has approximately the same length as the rail 4 and extends from one end of the rail 4 to the other end. The cover 20 is attached to one side (bottom surface 16) of the rail 4 so as to cover the scale 6 from the outside. The magnetic flux due to the magnetization pattern of the scale 6 is transmitted through the cover 20. Therefore, even if the cover 20 is interposed between the sensor head 30 and the scale 6, the detection of magnetic flux is not affected.

By placing the sensor head 30 facing the scale 6 and reading the magnetization pattern, the position of the magnetic sensor 10 and, in turn, the position of the moving body 2 can be detected. The magnetic sensor 10 transmits the detected position information to an external device via the cable 12.

As shown in FIG. 5, the scale 6 is disposed inside the cover 20 on the side surface of the rail 4, thereby preventing foreign matter from adhering to it from the outside. The peripheral edge of the cover 20 abuts on the same plane of the rail 4, and continuous welding is performed along the four sides of the rail, ensuring sealing at the joint between the cover 20 and the rail 4. . The method of fixing the cover 20 by welding will be described in detail later.

The first end 44a of the hole 42 and the scale 6 are separated from each other in the longitudinal direction of the rail 4. That is, when viewed from the front of the scale 6, that is, when viewed in the Y direction (second direction) that intersects the X direction (first direction) in which the scale 6 extends, the first end 44a and the scale 6 are , are arranged in the recess 18 side by side without overlapping in the X direction.

FIG. 6 is a sectional view of the rail 4 shown in FIG. 5. 6(A) shows the BB cross section, FIG. 6(B) shows the CC cross section, FIG. 6(C) shows the DD cross section, and FIG. 6(D) shows the EE cross section. The left side of each figure is a sectional view, and the right side is an enlarged view of section F.

A scale 6 and a cover 20 are attached to one side of the rail 4 as shown in the figure (FIGS. 6(A) to 6(D)). The scale 6 is inserted so as to fit into the mounting portion 32 located near the center of the recess 18 (FIG. 6(A)). The distal end surface of the first support portion 36 supports the scale 6 as a support surface 36a. The opening width (width in the vertical direction) of the recess 18 and the width of the scale 6 are approximately equal. Grooves 46 are formed above and below the support surface 36a. The groove portion 46 forms a space S1 between the groove portion 46 and the back surface of the scale 6. A cover 20 is disposed to close the opening of the recess 18. The scale 6 is stably held by the cover 20 so as to be sandwiched between the back surface and the support surface 36a.

On the outside of the attachment part 32 in the recessed part 18, the depth of the groove part 46 is shallow, and the tip surface of the second support part 38 supports the cover 20 as a support surface 38a (FIG. 6(B)). The groove portion 46 forms a space S2 between the groove portion 46 and the back surface of the cover 20. A cover 20 is disposed so as to close the opening of the recess 18 in this portion as well. A space S2 is formed on both sides of the space S1 in the longitudinal direction, and these spaces communicate with each other.

The groove portion 46 communicates with the hole 42 at its longitudinal end (FIG. 6(C)). A first end 44a of the hole 42 opens into the space S2. With this configuration, the hole 42a (first hole) at one end of the rail 4 and the hole 42b (second hole) at the other end communicate with each other via the groove 46. Both ends of the cover 20 are hermetically fixed to the bottom surface 16 of the rail 4 (FIG. 6(D)).

The holes 42 provided at both ends of the rail 4 and the spaces S1 and S2 extending in the longitudinal direction of the rail 4 constitute an air passage through which air is circulated in order to confirm the sealing performance of the cover 20. The scale 6 is arranged in a region of the recess 18 corresponding to the space S1. Particularly in this area, it is necessary to prevent foreign matter and moisture from entering from the outside, so the cover 20 is required to have high sealing performance. Therefore, in this embodiment, a seal confirmation test is performed after the scale 6 and cover 20 are assembled to the rail 4.

In this seal confirmation test, the rail 4 is placed with the surface of the cover 20 facing upward, liquid (water, oil, coolant, etc.) is stored on the side of the rail 4, and air is supplied to the air passage. That is, air discharged from an air supply source (not shown) is introduced into one hole 42a and is discharged from the other hole 42b. At this time, if no air bubbles are generated in the liquid, it can be determined that there is no leakage of air from between the cover 20 and the rail 4, that is, the sealing performance is ensured. If the sealing performance is not ensured, take measures such as re-welding the cover 20.

Since this seal confirmation test is performed only when the position detection device 1 is manufactured, the air passage becomes unnecessary thereafter. Therefore, after the seal confirmation test, the second ends 44b of each of the two holes 42 are closed. For example, the second end 44b can be closed by sealing it with a plug or by pouring and hardening a brazing material. By providing separate air inlets and outlets on the rail 4 to form air passages in this way, it is possible to check whether the air passages are clogged by detecting the air flow rate, ventilation pressure, etc. .

FIG. 7 is a diagram showing a method of welding the cover 20 to the rail 4. This figure is a view of the rail 4 seen from the front of the cover 20, and the chain double-dashed line in the figure indicates the welded portion W. For convenience of explanation, the structural elements shown in FIG. 1 are shown briefly in the longitudinal direction of the rail 4.

The cover 20 extends from one end of the rail 4 to the other end. The moving body 2 moves on the rail 4, but since the magnetic sensor 10 occupies a part of the area in the longitudinal direction of the moving body 2 and is moved to one side in the longitudinal direction, the moving body 2 is moved on the rail 4. The movement range (stroke) is necessarily larger than the length of the scale 6. The scale 6 can be shorter than the rail 4 in the longitudinal direction. Due to this relationship, the cover 20 is larger than the scale 6 in the longitudinal direction.

Holes 42 forming air passages are provided at both ends of the rail 4. Therefore, the cover 20 is provided so as to cover the holes 42 at both ends. The cover 20 is arranged so that its peripheral edge abuts on the same plane of the bottom surface 16 and surrounds the recess 18. In this state, continuous welding is performed along the four sides of the cover 20. That is, when viewed in a direction intersecting the extending direction of the scale 6, the cover 20 is welded in a rectangular shape surrounding the scale 6, and the cover 20 is fixed to the rail 4, and the four square-shaped The corners are welded.

Since the welded portion W is provided outside the recess 18 so as to surround the recess 18, foreign matter can be prevented from entering the recess 18. As shown in the figure, the distance X1 between one end of the scale 6 and one end of the weld W in the longitudinal direction of the rail 4 is larger than the distance Y1 between one end of the scale 6 and one end of the weld W in the short direction of the rail 4. big enough. The scraper 28 moves beyond one end of the scale 6 and cleans the top of the cover 20.

The scraper 28 moves with its tip in contact with the cover 20, but since it is made of a flexible member as mentioned above, if it interferes with the bead (unevenness) of the weld W, there is a possibility of damage due to wear etc. There is. In this regard, in this embodiment, by making the interval X1 sufficiently large, such interference can be prevented. The width of the portion where the tip of the scraper 28 contacts the cover 20 (that is, the length of the abutting portion of the cover 20 in the lateral direction) is larger than the width of the scale 6, and smaller than the interval. Therefore, the scraper 28 does not interfere with the upper and lower welds W.

Next, a method of manufacturing the rail 4 in which the scale 6 is built-in will be described.
8 and 9 are diagrams schematically showing the welding method employed in this embodiment.
Laser welding using a diffractive optical element (DOE) is used to weld the cover 20 to the rail 4. As shown in FIG. 8A, a laser L output from an oscillator (not shown) passes through a diffractive optical element 50 and is branched into a first laser L1 and a second laser L2. Thereby, two rows of welding parallel to each other can be performed simultaneously.

By rotating the diffractive optical element 50 (see the white arrow in the figure), the angles of the two rows of lasers can be changed as shown in FIG. 8(B). As the laser beam, a YAG laser, a CO2 laser, an excimer laser, etc. can be used as appropriate. The interval T between the first laser L1 and the second laser L2 can be changed by changing the position of the diffractive optical element 50, such as by moving the diffractive optical element 50 back and forth. Alternatively, the interval T can also be changed by rotating the diffractive optical element 50.

When manufacturing the rail 4, after forming the general shape of the rail 4 by cutting a metal material, holes 42a are formed in the rail 4 (first hole forming step), and holes 42b are formed in the rail 4 (second hole forming step). forming process). Next, as shown in FIG. 4, with the scale 6 placed in the recess 18 extending along the rail 4, a rectangular cover 20 is placed on the rail 4 so as to cover the scale 6 (placement step ).

Then, the welding process shown in FIG. 9 is performed. First, one end of the cover 20 is welded while moving the first laser L1 and the second laser L2 in the lateral direction of the cover 20 (FIGS. 9(A) and 9(B)). Next, by rotating the diffractive optical element 50, the angles of the two rows of lasers are changed by 90 degrees, and then the parallel long sides of the cover 20 are simultaneously welded while moving the cover 20 in the longitudinal direction (Fig. 9 (C), (D)). At this time, the interval between the two rows of lasers is T=T1. The interval T1 is larger than the width of the recess 18 and smaller than the width of the cover 20 (see FIG. 7).

When the two rows of lasers reach the other end of the cover 20, the angle of the two rows of lasers is changed by 90 degrees by rotating the diffractive optical element 50 again, and the cover 20 is moved while moving in the lateral direction of the cover 20. Weld the other end. In this way, in this embodiment, DOE is employed when welding the cover 20, and welding in the longitudinal direction and welding in the lateral direction of the cover 20 is performed.

Since the welding process in the longitudinal direction and the welding process in the transverse direction are performed continuously, the cover 20 can be efficiently joined to the rail 4. A cover 20 is welded to a rectangular shape surrounding the scale 6 and fixed to the rail 4. As shown in FIG. 7, the four sides of the cover 20 can be welded so that the four corners are connected. As a result, the hole 42a, the gap between the side surface of the rail 4 and the back surface of the cover 20, and the hole 42b communicate with each other, forming the above-mentioned air passage.

The position detection device 1 has been described above based on the embodiment.
In the position detection device 1, the cover 20 is welded in a square shape at a position surrounding the scale 6 and fixed to the rail 4, and the four corners of the square shape are formed by welding. Therefore, the sealing performance of the joint between the cover 20 and the rail 4 can be ensured, and the scale 6 built into the rail 4 can be effectively protected from external foreign substances (chip particles, coolant, etc.).

Further, when manufacturing the rail 4, two holes 42 were provided and communicated with the spaces S1 and S2 formed between the cover 20 and the recess 18, thereby forming an air passage. By making it possible to perform a seal confirmation test, it is possible to easily check the quality of laser welding. This makes the sealing performance of the joint between the cover 20 and the rail 4 more reliable, and leads to protection of the scale 6 from foreign substances.

Furthermore, by employing DOE for laser welding the cover 20 and performing welding using two branched lasers simultaneously and continuously, the efficiency of the welding process can be improved. That is, by moving two rows of lasers in the longitudinal direction of the cover 20, both ends of the cover 20 in the width direction (short direction) can be simultaneously welded. Further, by rotating the DOE, welding in the short direction and welding in the longitudinal direction of the cover 20 can be made continuous. Thereby, efficient welding can be achieved. As a result, the rail 4 having the built-in scale 6 can be manufactured efficiently. By simultaneously welding both ends of the cover 20 in the width direction in this manner, distortion of the cover 20 due to welding temperature (deformation due to thermal distortion) can be suppressed.

It should be noted that the present invention is not limited to the above-described embodiments and modified examples, and can be embodied by modifying the constituent elements without departing from the scope of the invention. Various inventions may be formed by appropriately combining a plurality of components disclosed in the above embodiments and modified examples. Furthermore, some components may be deleted from all the components shown in the above embodiments and modified examples.

[Modified example]
FIG. 10 is a diagram schematically showing a welding method according to a modification.
This modification differs from the above embodiment in that the recess 118 extends from one longitudinal end of the rail 104 to the other end. In such a configuration, it is necessary to prevent foreign matter from entering from the end of the rail 104. Therefore, in this modification, metallic spacers 120 are arranged at one end and the other end of the recess 118 to close the opening at the end. The spacer 120 may be made of the same material as the cover 20, for example, stainless steel.

When manufacturing the rail 104, the general shape of the rail 104 is formed in the same manner as in the above embodiment, and then the holes 42a and 42b are bored (first and second hole forming steps). Subsequently, the scale 6 is placed in the recess 118 extending along the rail 104, and spacers 120 are placed at both ends of the recess 118 (FIGS. 10A and 10B). Note that the spacer 120 has a width approximately equal to that of the recess 118 and a length shorter than the scale 6. The thickness of the spacer 120 is approximately equal to the depth of the recess 118.

Subsequently, the spacer 120 is welded to the rail 104 (FIG. 10(C)). First, while moving the first laser L1 and the second laser L2 in the longitudinal direction of the spacer 120, two parallel sides of the spacer 120 are simultaneously welded (FIGS. 10C and 10D: welding process). At this time, the interval between the two rows of lasers is T=T2. The interval T2 is smaller than the interval T1. Subsequently, the laser is stopped, and with the scale 6 placed in the recess 118, the cover 20 is placed so as to cover the scale 6 (placement step).

Then, the cover 20 is welded to the rail 104 in the same manner as in the above embodiment. First, after rotating the diffractive optical element 50, the cover 20 is welded in the width direction while moving two rows of lasers in the width direction of the cover 20 (FIG. 10(E)). At this time, one end of the cover 20 is welded to the spacer 120 and the rail 104.

Next, by rotating the diffractive optical element 50, the angles of the two rows of lasers are changed by 90 degrees and the interval between them is T=T1, and then the parallel long sides of the cover 20 are moved while being moved in the longitudinal direction of the cover 20. are welded at the same time (Fig. 10(F)). When the two rows of lasers reach the other end of the cover 20, the angle of the two rows of lasers is changed by 90 degrees by rotating the diffractive optical element 50 again, and the cover 20 is moved while moving in the lateral direction of the cover 20. Weld the other end. In this way, also in this modification, welding in the longitudinal direction and welding in the transverse direction of the cover 20 are performed continuously.

According to this modification, good sealing performance can be ensured even if the rail has a structure with a recess that extends from one longitudinal end to the other, such as when the general shape of the rail is obtained by extrusion molding (pultrusion processing). can. Effects similar to those of the above embodiment can be obtained. This modification does not have a configuration in which the four sides of the cover 20 are welded to the same plane of the same component in the rail 4 as in the above embodiment. However, similar sealing performance can be ensured by welding the four sides of the rail of the cover 20 to the same plane in which the two parts, the rail 104 and the spacer 120, are assembled.

[Other variations]
In the above embodiment, an example was shown in which laser welding by DOE is performed in a rectangular shape. This quadrangular shape may be a rectangular shape with four corners forming 90 degrees as shown in FIG. It may be.

In the above modification (FIG. 10), the spacer 120 is fixed to the rail 104 by welding, but it may be fixed to the rail 104 by adhesive or other fixing means.

In the above embodiment, a configuration including both an absolute pattern and an incremental pattern is illustrated as a magnetization pattern in the scale. In a modified example, it may be configured to include only absolute patterns and not include incremental patterns.

In the above embodiment, an example is shown in which the position detection device 1 is applied to a machine tool, but the use of the position detection device is not limited to this, and the application of the position detection device is not limited to this. Any device can be applied as long as it is equipped with a sensor that detects a position.

1 position detection device, 2 moving body, 4 rail, 6 scale, 8 sensor unit, 9 holder, 10 magnetic sensor, 12 cable, 14 guide surface, 16 bottom surface, 18 recess, 20 cover, 24 scraper unit, 26 cover, 27 Screw, 28 Scraper, 30 Sensor head, 32 Mounting part, 34 Support part, 36 First support part, 36a Support surface, 38 Second support part, 38a Support surface, 42 Hole, 42a Hole, 42b Hole, 44a First end part, 44b second end, 46 groove, 50 diffractive optical element, 104 rail, 118 recess, 120 spacer, L laser, L1 first laser, L2 second laser, S1 space, S2 space, W welding part.

Claims (6)

a rail that guides a moving body and has a recess extending in a direction that guides the moving body;
a scale having a magnetized pattern formed on the applied magnetic material and disposed in the recess extending along the rail;
a cover disposed on the rail so as to close an opening of the recess in which the scale is accommodated;
The magnetic sensor for detecting the position of the moving body includes a magnetic sensor having a sensor head at a position facing the scale with the cover in between,
When viewed in a direction intersecting the extending direction of the scale, the cover is welded and fixed to the rail in a rectangular shape so as to surround the recess in which the scale is accommodated, so that the recess is fixed to the rail. and the cover, and the four corners of the square shape are formed by welding ,
The rail has a hole, a first end of the hole in the recess, and a second end opposite to the first end of the hole in a location other than the recess. death,
The position detection device , wherein the second end of the hole is closed . a rail that guides a moving body and has a recess extending in a direction that guides the moving body;
a scale having a patterned magnetic material and disposed in the recess extending along the rail;
a cover disposed on the rail so as to close an opening of the recess in which the scale is accommodated;
The magnetic sensor for detecting the position of the moving body includes a magnetic sensor having a sensor head at a position facing the scale with the cover in between,
When viewed in a direction intersecting the direction in which the scale extends , the cover is welded and fixed to the rail in a rectangular shape so as to surround the recess in which the scale is accommodated . A space surrounded by the recess and the cover is formed,
The rail has a hole, a first end of the hole in the recess, and a second end opposite to the first end of the hole in a location other than the recess . death,
The first end and the scale are arranged in the recess side by side without overlapping in the first direction when viewed in a second direction intersecting the first direction in which the scale extends,
The position detection device , wherein the second end of the hole is closed . The rail has a groove portion that forms the space between a support surface that supports the scale and a back surface of the scale in the recess ,
The position detection device according to claim 2, wherein the groove communicates with the hole. The holes include a first hole provided at one end of the rail and a second hole provided at the other end of the rail,
The position detection device according to claim 2 or 3, wherein the first hole and the second hole communicate with each other via the recess. The position detection device according to claim 1 or 2, wherein the cover is in contact with and welded to the same plane on the rail. The position detection device according to claim 1 or 2, wherein the cover extends from one end of the rail to the other end.

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