JP2001165644A - Displacement detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a displacement detector capable of eliminating the influence of the heat by a heating element to perform a precise measurement even when one of a fixed part and a movable table subjected to mounting constitutes the heating element. SOLUTION: This linear encoder 10 detects the linear displacement of the movable table 2 reciprocating to a fixed part 1 mounted on a drive unit constituting the heating element. This encoder 10 comprises a body 11 to be mounted on the fixed part 11 and a detector 12 to be mounted on the movable table 2. Since the body 11 has a groove part 13A on the outer surface, the heat of the fixed part 1 is released to the outside through the groove part 13A even if the fixed part 1 generates heat. Therefore, this heat is never transmitted to the inner part of the body 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a displacement detecting device which is attached to a driving device in which a movable table reciprocates with respect to a fixed portion, and detects a linear displacement of the movable table.

[0002]

2. Description of the Related Art Conventionally, a driving device for reciprocating a movable table with respect to a fixed portion is incorporated in a machine tool, a transfer device, or the like. In some of the driving devices, the movable table is controlled in positioning with high accuracy. In this case, a displacement detecting device is used to detect a linear displacement of the movable table with respect to a fixed portion of the driving device.

FIG. 9 is a schematic view of a conventional example showing a state in which a displacement detecting device is attached to a driving device. In FIG. 9, the movable table 100 has a basic structure in which a nut 102 is fixed to a lower surface of a machine table 101 on which articles and works are placed. The nut 102 is screwed to a ball screw 103. The ball screw 103 has both ends rotatably attached to a fixed portion (not shown).
One end thereof is connected to a rotary motor 104 composed of a servomotor. As the rotary motor 104 rotates in the forward and reverse directions, the movable table 100 reciprocates along the axial direction of the ball screw 103.

Since the positioning of the movable table 100 needs to be controlled with high precision, the rotary motor 104 has a rotary encoder 105 for detecting the speed of the movable table 100.
The movable table 100 and the fixed portion are provided with a displacement detection device 106 that detects the amount of linear movement of the movable table 100. This displacement detection device 106
Is composed of a linear encoder having a main body 107 attached to the fixed part and a detector 108 attached to the movable table 100. The detection signal sent from the detector 108 is a position / speed control device (controller) 10
9, the control signal of the position command is sent to the servo amplifier 110
Through the rotary motor 104.

[0005]

Generally, since a motor such as the rotary motor 104 is a heat source, when this heat is transmitted to the displacement detecting device or the movable table 100, the accuracy of the positioning control of the movable table 100 is reduced. I do. In the above-described conventional example, the rotary motor 104 is fixed at one location, and the location thereof is
And the displacement detection device 106, it is easy to take measures to prevent heat generated by the rotary motor 104 from affecting the movable table 100 and the displacement detection device 106.

Recently, in order to move the movable table 100 at high speed or at high acceleration / deceleration, a linear motor is being used in a driving device instead of a rotary motor. To move the movable table 100 using this linear motor, an exciting coil is attached to one of the movable table and the fixed part, and a magnet is attached to the other of the movable table and the fixed part. These coils and magnets are attached to a movable table and a fixed portion in a relatively wide range.

Generally, a moving coil type linear motor in which an exciting coil is integrated with a movable table is often used. When this type of linear motor is incorporated in a driving device, the movable table has an exciting source serving as a heat source. Since the coils are arranged in a wide range, the movable table itself becomes a heating element. The heat generated by the motor rises to about 100 ° C., although it varies depending on the load. This heat is directly transmitted to the displacement detection device constituted by the linear encoder, which causes the accuracy of the displacement detection device, deterioration of electronic components, and failure.

[0008] An object of the present invention is to eliminate the influence of heat generated by this heating element even when one of the fixed portion and the movable table to be attached constitutes a heating element, to suppress deterioration of electronic components, and to achieve high precision. Another object of the present invention is to provide a displacement detection device capable of performing measurement at a time.

[0009]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to achieve the above object by radiating heat generated by a heating element. Specifically, the displacement detection device of the present invention
One of a fixed portion and a movable table that reciprocates with respect to the fixed portion is attached to a driving device that forms a heating element, and is a displacement detection device that detects a linear displacement of the movable table. And a main body attached to one of the movable tables, and a detector attached to the other of the fixed portion and the movable table, and the main body or the detector attached to the heating element has a heat radiating portion on an outer surface thereof. It is characterized by having.

In the present invention having this configuration, even if the fixed portion or the movable table constituting the heating element generates heat, the main body or the detector attached to the heating element has a heat radiating portion on its outer surface. The heat of the heating element is released to the outside through the radiator. Therefore, heat is hardly transmitted to the inside of the main body or the detector, so that high-precision measurement can be performed without adversely affecting electronic components and the like provided inside the main body and the detector.

Here, in the present invention, the heat radiating portion is preferably a groove or a heat radiating plate. When the heat radiating portion is formed from the groove or the heat radiating plate, the heat radiating performance is improved because the body or the detector attached to the heating element has a large surface area on its outer surface. Further, the heat radiating portion may be formed to extend in a reciprocating direction of the movable table. In this configuration,
An airflow is generated with the reciprocation of the movable table, and the airflow satisfactorily radiates heat by sufficiently hitting the radiator.

Another object of the present invention is to achieve the above object by insulating heat generated by the heating element. Specifically, in the displacement detection device of the present invention, one of the fixed portion and the movable table that reciprocates with respect to the fixed portion is attached to a driving device that forms a heating element, and the linear displacement of the movable table is A displacement detection device for detecting the main body attached to one of the fixed portion and the movable table,
A detector attached to the other of the fixed part and the movable table, wherein a heat insulator is interposed between the heating element and a main body or a detector attached to the heating element. I do.

In this configuration, the heat transfer from the heating element to the displacement detecting device is prevented by the heat insulating material interposed between the heating element and the main body or the detector attached to the heating element. Therefore, heat is not transmitted to the inside of the main body and the detector of the displacement detection device, so that high-precision measurement can be performed without adversely affecting electronic components provided inside the main body and the detector. it can.

Here, the heating element and a main body or a detector attached to the heating element may be connected to each other by a heat insulating bolt. In this configuration, since the heating element and the main body or the detector in contact with the heating element are securely connected to each other by the bolt, these members do not shift with respect to the heating element. In addition, since the bolt is adiabatic, it is possible to prevent heat from being transmitted from the heating element to the main body or the detector of the displacement detection device through the bolt.

In the above, according to the present invention, the driving device is a linear motor, and the heating element is provided with an exciting coil.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a displacement detecting device according to the present invention will be described below in detail with reference to the accompanying drawings. In the following description, the same components will be denoted by the same reference numerals, and the description thereof will be omitted or simplified. [First Embodiment] A first embodiment is shown in FIGS. FIG. 1 is a schematic configuration diagram showing a state where the displacement detection device of the present embodiment is incorporated in a drive device.

In FIG. 1, a driving device is incorporated in a device such as a machine tool or a transport device, and includes a fixed portion 1 and a movable table 2 reciprocating with respect to the fixed portion 1. The movable table 2 is for placing articles and works (not shown). An excitation coil group 3 is provided on the fixed portion 1 along the reciprocating direction of the movable table 2, and a magnet 4 is provided on a portion of the movable table 2 facing the excitation coil group 3. A linear motor 5 is configured by the exciting coil group 3 and the magnet 4. When the exciting coil group 3 is energized, the movable table 2 provided with the magnet 4 reciprocates. In the first embodiment, since the excitation coil group 3 generates heat when energized, the fixing unit 1 forms a heating element.

A linear encoder main body 11 is mounted on the fixed portion 1, and a detector 12 is mounted on the movable table 2. A linear encoder 10 is configured as a displacement detection device that detects a linear displacement of the movable table 2 from the main body 11 and the detector 12. The detection signal sent from the detector 12 is sent to the position / speed control device 6, and the position / speed control device 6 converts the control signal generated based on the detection signal into the excitation coil group via the servo amplifier 7. 3 to control the position of the movable table 2.

FIGS. 2 and 3 show the detailed configuration of the linear encoder 10. FIG. FIG. 2 is a front view of the linear encoder 10, and FIG. 3 is a cross-sectional view of the linear encoder 10. In FIG. 1, the detector 1 is placed on the main body 11.
2 and 3, the detector 12 is disposed below the main body 11 in FIGS. 2 and 3. In FIGS. 2 and 3, a main body 11 is formed of aluminum and has a substantially box-shaped casing 13 whose longitudinal direction coincides with the direction in which the exciting coil group 3 is arranged, and a main body provided inside the casing 13. It comprises a scale 14 and electronic components (not shown), and a plurality of mounting portions 15 fixed to the upper portion of the casing 13 for mounting the main body 11 on the front of the fixing portion 1.

The casing 13 has both open end faces closed by lids 16, and a groove 13 A as a heat radiating section is formed on the outer surface of the upper surface and the front surface (the surface distant from the fixing portion 1).
Extend in the reciprocating direction of the movable table 2 (the longitudinal direction of the main body 11). This groove 13A is
It has a rectangular cross-section, and a plurality of casings are formed on the upper surface and the front surface of the casing 13 at equal pitches. A plurality of grooves 13A on the upper surface of the casing 13 are arranged in a straight line with the mounting portion 15 interposed therebetween in order to prevent interference with the mounting portion 15. 2 and 3, the groove 13A is used.
Is a rectangular cross section, but any specific shape of the cross section is not limited as long as it has a heat radiation effect. For example, the shape may be a triangular cross section, a semicircular shape, or the like.

The detector 12 comprises a casing 12A attached to the movable table 2, an index scale 17 provided inside the casing 12A, and electronic parts (not shown). Detector 12
The index scale 17 is formed in a U-shaped cross section so as to sandwich the main scale 14 of the main body 11, and the relative positions of these scales 14 and 17 are sent to a position / speed control device (not shown) through a cable 18.

Therefore, (1) In the first embodiment, the fixing portion 1
Is attached to a driving device constituting a heating element, and
A linear encoder 10 for detecting a linear displacement of a movable table 2 reciprocating with respect to a main body 11 attached to a fixed portion 1 and a detector 12 attached to the movable table 2; The main body 11 attached to a certain fixed part 1 has a heat radiating part (groove 13
A) is provided, so that even if the fixing portion 1 generates heat, the heat of the fixing portion 1 is released to the outside through the heat radiating portion.
Therefore, since this heat is hardly transmitted to the inside of the main body 11, high-precision measurement can be performed without adversely affecting electronic parts and the like provided inside the main body 11 and the detector 12.

(2) Since the heat radiating portion is formed by the groove 13A, the main body 11 attached to the fixing portion 1, which is a heating element, has a large surface area on its outer surface, so that the heat radiating performance is improved. (3) Since the plurality of grooves 13A are formed, the outer surface area of the main body 11 is increased from this point, and the heat radiation performance is improved. (4) Since the groove 13A, which is a heat radiating portion, is formed to extend in the reciprocating direction of the movable table 2, an airflow is generated along with the reciprocating movement of the movable table 2, and this airflow is sufficiently generated in the groove 13A. , Heat is efficiently dissipated. (5) In the first embodiment, if the cross-sectional shape of the groove portion 13A is rectangular, the forming operation becomes easy.

Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIGS. Second
The second embodiment differs from the first embodiment in the structure of the heat radiating unit, and the other configuration is the same as that of the first embodiment. The linear encoder 20 of the second embodiment is used for controlling the positioning of the movable table 2 as in the linear encoder 10 shown in FIG.

FIGS. 4 and 5 show a detailed configuration of the linear encoder 20 according to the second embodiment. FIG. 4 is a front view of the linear encoder 20, and FIG. 5 is a cross-sectional view of the linear encoder 20. 4 and 5,
The linear encoder 20 includes a main body 21 attached to the fixed unit 1 and a detector 12 attached to the movable table 2. The main body 21 is made of aluminum and has a substantially box-shaped casing 23 whose longitudinal direction coincides with the direction in which the exciting coil group 3 is arranged, a main scale 14 provided inside the casing 23, and electronic components (not shown). And a mounting portion 15 fixed to an upper portion of the casing 13.

The casing 23 has a heat radiating plate 23A as a heat radiating portion formed on the outer surface of the upper surface thereof in a row extending in the reciprocating direction of the movable table 2, and a heat radiating plate as a heat radiating portion is formed on the front outer surface. 23A extend in the reciprocating direction of the movable table 2 and are formed in two rows. The heat radiating plates 23A provided on the front of the casing 23 are spaced apart from each other by a predetermined distance and are parallel to the longitudinal direction of the casing 23. In the present embodiment, a plurality of rows of heat radiating plates 23A may be provided on the upper surface of the casing 23, or a single row of heat radiating plates 23A may be provided on the front surface of the casing 23.

The heat radiating plate 23A includes a rising portion 23B protruding from the outer surface of the casing 13 and a rising portion 23B.
B is formed in a T-shaped cross section with a parallel portion 23C made parallel to the outer surface at the tip of B. These heat sinks 23
A is formed of aluminum having a high heat radiation effect similarly to the casing 23. Heat sink 23 on the upper surface of casing 13
A is an attachment portion 15 for preventing interference with the attachment portion 15.
Are arranged side by side on a straight line. In FIGS. 4 and 5, the cross-sectional shape of the heat radiating plate 23A is T-shaped. For example, the shape may be Y-shaped or L-shaped in cross section.

Therefore, the second embodiment has the following functions and effects in addition to the same functions and effects as (1) and (4) of the first embodiment. That is, (6) In the second embodiment, since the heat radiating portion is formed from the heat radiating plate 23A, the main body 11 attached to the fixing portion 1 as the heating element has a large surface area on its outer surface, so that the heat radiating performance is improved. improves. (7) Heat sink 2
If 3A is formed to have a T-shaped cross section, the structure of the heat sink 23A is simplified.

[Third Embodiment] Next, a third embodiment of the present invention will be described with reference to FIGS. Third
Unlike the first embodiment, the second embodiment is characterized by a configuration in which heat is insulated from the heating element, and the other configurations are the same as the first embodiment. The linear encoder 30 of the third embodiment is used for controlling the positioning of the movable table 2 as in the linear encoder 10 shown in FIG.

FIGS. 6 and 7 show the detailed configuration of the linear encoder 30 according to the third embodiment. FIG. 6 is a front view of the linear encoder 30, and FIG. 7 is a sectional view of the linear encoder 30. 6 and 7,
The linear encoder 30 includes a main body 31 attached to the fixed unit 1 and the detector 12 attached to the movable table 2. The main body 31 includes a substantially box-shaped casing 33 formed of aluminum and having a longitudinal direction coinciding with the direction in which the exciting coil group 3 is arranged, a main scale 14 provided inside the casing 33, and electronic components (not shown). And a mounting portion 15 fixed to an upper portion of the casing 13.

A heat insulating material 3 is provided between the mounting portion 15 and the fixing portion 1.
4 are interposed. The heat insulating material 34 is a sheet molded from ceramics and heat-resistant plastic (for example, Bakelite), and the sheet has a slightly larger area than the front of the mounting portion 15. Insulation material 34
Have different thicknesses in the upper and lower portions in order to eliminate a gap between the front surface of the fixing portion 1 and the mounting portion 15 and the casing 33. The mounting of the mounting portion 15 to the fixing portion 1 is performed by using the heat insulating bolt 3
5 is performed. The heat-insulating bolt 35 is formed from a heat-insulating material such as ceramics or heat-resistant plastic. A heat-insulating washer 36 is interposed between the head 35A and the recess 15A of the mounting portion 15. This washer 36 is formed from ceramics and heat-resistant plastic.

Therefore, (8) In the third embodiment, the fixing portion 1 which is a heating element and the main body 3 attached to the fixing portion 1
Since a heat insulating material 34 is interposed between the linear encoder 30 and the linear encoder 30 by the heat insulating material 34,
The transfer of heat to the device is prevented. Therefore, heat is hardly transmitted to the inside of the main body 31 of the linear encoder 30 and the inside of the detector 12, so that the electronic parts provided inside the main body 31 and the inside of the detector 12 are not adversely affected, and high-precision measurement is possible. It can be performed.

(9) In the third embodiment, the fixing portion 1 and the main body 31 in contact with the fixing portion 1 are securely connected to each other by the heat insulating bolt 35. No misalignment occurs. Moreover,
(10) Since the bolt 35 is heat-insulating, heat can be prevented from being transmitted from the fixing portion 1 to the main body 31 of the linear encoder 30 through the heat-insulating bolt 35. (11) Even if the bolt 35 is a bolt made of a normal metal material, the head 35A of the bolt 35 and the recess 15A
If a heat-insulating washer 36 is interposed between the fixed portion 1 and the main body 31 of the linear encoder 30, heat can be prevented from being transmitted through the heat-insulating washer 36.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various improvements and design changes may be made without departing from the gist of the present invention. Is possible. For example,
In each of the above embodiments, the fixed portion 1 is a heating element. However, in the present invention, the movable table 2 may be a heating element, and the detector 12 or the main bodies 11, 21, 31 may be attached to the movable table 2.

That is, a heating element is formed by attaching an exciting coil to the movable table 2, and the main bodies 11, 21, 31 of the linear encoders 10, 20, 30 are attached to the movable table 2.
Alternatively, the detector 12 may be attached. In the first and second embodiments, the main bodies 11 and 21 attached to the movable table 2 are provided.
Alternatively, a heat radiating portion is formed on the outer surface of the casing of the detector 12. In the case of the third embodiment, as shown in FIG. 8A, a heat insulating material 34 is interposed between the movable table 2 and the detector 12, or as shown in FIG. A heat insulating material 34 is interposed between the table 2 and the main body 31.

In each of the above embodiments, the linear encoders 10, 20, and 30 optically detect the relative position of the movable table. However, the linear encoders detect the relative position of the movable table by magnetic force. You may. Further, in each of the above embodiments, the case where the fixed unit 1 and the movable table 2 generate heat by the exciting coil is applied. However, the present invention is not limited to this case, and the fixed unit 1 and the movable table 2 are not limited to this case. This also applies to the case where heat is generated.

In the first and second embodiments, the heat radiating portion is the groove 13A or the heat radiating plate 23A. However, the shape of the heat radiating portion is not limited as long as it has a heat radiating function.
One or more projections formed on the outer surfaces of the casings 13 and 23 may be used. In this case, the projections may be cylindrical or prismatic, or may be conical or pyramidal, and these projections may be arranged regularly but irregularly. It may be something.

[0038]

As described above, according to the present invention, even when one of the fixed portion and the movable table to be attached forms a heating element, the heat generated by the heating element is radiated or insulated. Therefore, there is an effect that measurement can be performed with high accuracy by eliminating the influence of heat due to the heating element.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating a state where a displacement detection device (linear encoder) according to a first embodiment of the present invention is incorporated in a drive device.

FIG. 2 is a front view of the linear encoder according to the first embodiment.

FIG. 3 is a cross-sectional view of the linear encoder according to the first embodiment.

FIG. 4 is a front view of a linear encoder according to a second embodiment.

FIG. 5 is a cross-sectional view of a linear encoder according to a second embodiment.

FIG. 6 is a front view of a linear encoder according to a third embodiment.

FIG. 7 is a sectional view of a linear encoder according to a third embodiment.

8A and 8B are perspective views schematically showing a modification of the present invention.

FIG. 9 is a schematic diagram showing a state in which a conventional displacement detection device is attached to a driving device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixed part 2 Movable table 3 Excitation coil group 4 Magnet 5 Linear motor 10,20,30 Linear encoder 11,21,31 Main body 12 Detector 13 Casing 13A Groove 23A Heat sink 34 Heat insulating material 35 Heat insulating bolt

Claims (7)

[Claims] 1. A displacement detecting device for detecting a linear displacement of a movable table, wherein one of a fixed section and a movable table reciprocating with respect to the fixed section is attached to a driving device constituting a heating element. And a main body attached to one of the fixed part and the movable table, and a detector attached to the other of the fixed part and the movable table. The main body or the detector attached to the heating element has an outer surface. A displacement detecting device, further comprising a heat radiating portion. 2. The displacement detecting device according to claim 1, wherein the heat radiating portion is a groove. 3. The displacement detecting device according to claim 1, wherein the heat radiating portion is a heat radiating plate. 4. The displacement detection device according to claim 1, wherein the heat radiating portion is formed to extend in a reciprocating direction of the movable table. 5. A displacement detecting device, wherein one of a fixed portion and a movable table reciprocating with respect to the fixed portion is attached to a driving device constituting a heating element, and detects a linear displacement of the movable table. And a detector attached to one of the fixed part and the movable table, and a detector attached to the other of the fixed part and the movable table, the heating element, and a main body or a detector attached to the heating element And a heat insulating material is interposed between the displacement detecting device and the displacement detecting device. 6. The displacement detection device according to claim 5, wherein the heating element and a main body or a detector attached to the heating element are connected to each other by a heat insulating bolt. apparatus. 7. The displacement detection device according to claim 1, wherein the driving device is a linear motor, and an excitation coil is attached to the heating element. apparatus.