JPH0412405B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a linear encoder, and particularly to a linear encoder suitable for detecting the relative position of a tool and a workpiece in machine tools such as lathes and drilling machines.

[Background of the invention]

For example, an incremental linear encoder is used as a measuring device for detecting the relative position between a tool and a workpiece in a machine tool such as a lathe. This linear encoder has multiple magnets arranged in a straight line on a shaft-like member that moves with the tool.
and a magnetic scale in which each magnet is arranged to face each other with the same polarity as the adjacent magnet, a position sensor that generates a pulse signal in response to a magnet formed by the magnets of the magnetic scale by movement of the magnetic scale, and It is equipped with an arithmetic device that counts pulse signals from the sensor and calculates the amount of movement of the tool, and can detect the relative position of the tool and the workpiece. However, conventional linear encoders of this type have a problem in that errors occur in counted values when the magnetic scale moves due to a power outage or when the position of the magnetic scale is changed when it is not in a counting state.

Therefore, in addition to installing a magnet on the magnetic scale that serves as a reference point for counting the relative position of the tool and workpiece,
A configuration was adopted in which a sensor sensitive to the magnetic field of this magnet was added to detect the relative position of the tool and workpiece based on a reference point. According to the linear encoder configured in this way, even if the magnetic scale moves due to ellipticity due to a power outage or the position of the magnetic scale changes when it is not in the counting state, the relative position of the tool and workpiece can be maintained. is counted from the reference point, so errors in the counted values can be corrected.

However, if one reference point is provided, the linear encoder cannot be used effectively depending on the type of work, so a method having a plurality of reference points has been proposed. However, in conventional linear encoders with multiple reference points, each reference point was fixed, so encoders had to be manufactured according to the type of workpiece, etc., and the number of types of encoders increased. Furthermore, because the magnetic scale had to be moved to a specified reference point depending on the type of workpiece, etc., the relative position between the tool and the workpiece could not be detected quickly.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to unify the product types of linear encoders and to speed up relative position detection by linear encoders.

[Summary of the invention]

The present invention provides a moving device that has a cylinder in which a plurality of reference point magnets are arranged and moves along the axial direction of the cylinder, and a moving device that is inserted into the cylinder and moves along the axial direction of the cylinder. A magnetic scale in which a plurality of magnets are linearly arranged on a shaft-like member that extends and moves together with the cylindrical body, and each magnet is arranged opposite to the adjacent magnet with the same polarity, and the magnetic scale and the cylindrical body are connected to each other. A position sensor is inserted between the magnetic scale and the cylindrical body, and generates a pulse signal in response to the magnetic field formed by the magnet of the magnetic scale when the magnetic scale moves. Due to movement,
A reference point sensor that generates a magnetic field detection signal in response to the magnetic field generated by the magnet in the cylinder, and a position sensor that receives the output signals of the position sensor and reference point sensor and generates a pulse signal of the position sensor based on the magnetic field detection signal of the reference point sensor. a calculation device that counts and calculates the amount of movement of the moving device;
Each magnet of the moving device is characterized in that the object is achieved by linear encoders disposed at different positions in the axial direction and the radial direction of the cylinder.

[Embodiments of the invention]

Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 1 shows the configuration of a preferred embodiment of the present invention.

In FIG. 1, a moving device 10 that reciprocates in the horizontal direction indicated by an arrow X has brackets 12 and 1.
A cylindrical cylinder case 16 is fixed to the brackets 12 and 14. This cylinder case 16 has three magnet rings 18, 2 as shown in FIG.
0 and 22 are buried spaced apart along the axial direction. The magnet rings 18, 20, 22 are the third
It is formed in a semicircle as shown in figures a to c,
They are embedded in different positions in the radial direction of the cylinder case 16.

Further, as shown in FIG. 2, a shaft-shaped rod scale 24 extending along the axial direction of the cylinder case 16 is inserted into the cylinder case 16, and both ends of the rod scale 24 are connected to the bracket 12, It is fixed at 14. This rod scale 24 has a plurality of magnets 26 arranged linearly along the axial direction on its surface side, and each magnet 26 is arranged to face an adjacent magnet with the same polarity, thereby forming a magnetic scale.

Pistons 30 and 32 are inserted between the cylinder case 16 and the rod scale 24. A magnet 2 disposed on the rod scale 24 is located on the side of the pistons 30, 32 facing the rod scale 24.
position sensor 3 that generates a pulse signal in response to
4 are buried. Further, a magnet ring 1 is provided on the inner peripheral surface side of the cylinder case 16 of the piston 32.
A reference point sensor 36 is embedded therein, which generates a magnetic field detection signal in response to the magnetic field generated from the sensors 8, 20, and 22. Furthermore, one end of the pistons 30, 32 is fixed to the end of a cylindrical body 38 surrounding the rod scale 24, and to the ends of rods 40, 42 extending along the axial direction of the rod scale 24.

The other ends of the cylindrical body 38 and rods 40, 42 are fixed to a detector unit 44, as shown in FIG. The detector unit 44 is fixed to a bracket 48 erected on a fixed stay 46. The detector unit 44 has a built-in arithmetic unit, and this arithmetic unit includes the rods 40, 4.
Output signals from the position sensor 34 and the reference point sensor 36 are supplied through signal lines (not shown) disposed in the space between the position sensor 2 and the cylindrical body 38. and,
This arithmetic device is configured to calculate the amount of movement of the moving device 10 by counting the pulse signal of the position sensor 34 based on the magnetic field detection signal of the reference point sensor 36. And this calculated value is the output cable 50
is supplied to a control device that controls the mobile device 10 and the like.

Furthermore, the fixed stay 46 is rotatably fixed around the cylindrical body 38. Then, as shown in FIG. 3, when the fixed stay 46 rotates 90 degrees from the state of a in FIG. 3 where the reference point sensor 36 is located at the center of the magnet ring 18,
The position sensor 34 is now positioned approximately at the center of the magnet ring 20. Furthermore, fixed stay 4
6 is rotated by 90 degrees from state b, the reference point sensor 36 is positioned approximately at the center of the magnet ring 22. Therefore, the fixed stay 46
When in the position shown in FIG. When in the position shown in b in the figure, the reference point sensor 36 is sensitive to the magnetic field of the magnet ring 20 and the magnetic field detection signal 1
Generates 02. Furthermore, the fixed stay 46 is the first
When in the position shown at c in the figure, the reference point sensor 36 is sensitive to the magnetic field of the magnet ring 22 and generates a magnetic field sensing signal 104.

In the above configuration, when the moving device 10 reciprocates in the direction of the arrow X when the fixed stay 46 is at the position a in FIG. It is counted by an arithmetic unit based on 32 output pulses.
The amount of movement of the moving device 10 is calculated based on the magnetic field detection signal detected by the reference point sensor 36 in response to the magnetic field of the magnet ring 18. When the fixed stay 46 is at the position shown in FIG. 1 b or FIG. This is performed based on a magnetic field detection signal sensitive to the magnetic field of the ring 22.

As described above, in this embodiment, the mobile device 10
When calculating the amount of movement, three magnet rings 18, 20, and 22 are provided that serve as the reference for the counted value, so you can select the reference point according to the application by simply changing the position of the fixed stay 46. be able to.
Therefore, even when changing the reference point depending on the type of workpiece, etc., an arbitrary reference point can be selected without moving the magnetic scale to a fixed reference point as in the conventional case. The amount of movement can be measured quickly, and the product types of encoders can be standardized.

FIG. 5 shows an embodiment of a device for automatically moving the detector unit 44 into the states a, b, and c of FIG.

In FIG. 5, a bracket 48 to which a detector unit 44 is fixed is fixed to an arm 60 formed in a U-shape, and the side of the arm 60 is connected to the shaft 6.
2 to the rotating shaft of the indexing motor 64. Further, an indexing detection shaft 66 is connected to the rotating shaft of the indexing motor 64, and a dog plate 68 is connected to this indexing detection shaft 66. A dog 70 is fixed to one end of the dog plate 68. Support base 72 on which index motor 64 is placed
Index position detection sensors 76, 78, and 80 are arranged on the surface of the side plate 74 that is erected at a distance along the rotational direction of the dog 70. And dog 7
When the index position detection sensor 74 comes into contact with the dog 70, the detector unit 44 is at the position shown in FIG. When this happens, the detector unit 44 is in the position b in FIG. Furthermore, when the dog 70 and the indexing position detection sensor 80 detect the rotation of the indexing motor 64, the detector unit 44
It is configured to be in the position shown in c in the figure.

In this way, the detector unit 44 is automatically moved to the positions a to c in FIG. 1 by rotationally driving the detector unit 44 using the automatic reference point selection device as shown in FIG. be able to. Note that when the dog 70 and the indexing position detection sensors 76, 78, and 80 come into contact with each other, the driving of the indexing motor 64 is stopped and one of the states a to c in FIG. 1 is maintained.

Further, in the above embodiment, it has been described that three magnet rings are provided, but the number of magnet rings is not limited to three, and by providing a large number of magnet rings, the type of work or A reference point can be set according to the purpose. Further, the shapes of the magnet rings 18 to 22 are not limited to semicircular shapes, but shapes other than semicircular shapes can be arranged at different positions in the axial and radial directions of the cylinder case 16. It is also possible to configure multiple reference point sensors.

Furthermore, in the above embodiment, it has been described that the position of the detector unit 44 is changed when changing the reference point, but even if the position of the detector unit 44 is not changed, the reference point can be changed according to the level of the magnetic field detection signal. It is also possible to determine the position of.

〔Effect of the invention〕

As explained above, according to the present invention, a plurality of magnets are disposed at different positions in the axial direction and radial direction of the cylinder in the cylinder constituting the moving device, and the magnets are sensitive to these magnets. The amount of movement of the moving device is calculated by counting the pulse signal of the position sensor based on the magnetic field detection signal of the reference point sensor, so even when changing the reference point depending on the type of workpiece or application, it is easy to change the reference point. This has the excellent effect of being able to easily perform the measurement, shortening the measurement time for calculating the amount of movement, and standardizing the product types of linear encoders.

[Brief explanation of drawings]

a, b, and c in FIG. 1 are respectively a block diagram showing one embodiment of the present invention, FIG. 2 is an internal block diagram of the cylinder case 16 shown in FIG. 1, and a, b, and c in FIG. 3 are respectively A diagram for explaining the positional relationship between the reference point sensor and the magnet ring when the detector unit 44 shown in FIG. 1 changes to a, b, and c in FIG. 1, and a to d in FIG. 4 are reference points. FIG. 5, which is an explanatory diagram of the operation of the sensor, is a configuration diagram of the automatic reference point selection device. 10...Movement device, 16...Cylinder case, 1
8, 20, 22... Magnet ring, 24... Rod scale, 30, 32... Position sensor, 36... Reference point sensor, 44... Detector unit.

Claims (1)

[Claims] 1. A moving device that has a cylindrical body in which a plurality of reference point magnets are arranged and moves along the axial direction of the cylindrical body, and a moving device that is inserted into the cylindrical body and extends along the axial direction of the cylindrical body. A magnetic scale is inserted between the magnetic scale and the cylindrical body, in which a plurality of magnets are linearly arranged on a shaft-like member that moves together with the cylindrical body, and each magnet is arranged facing the adjacent magnet with the same polarity. A position sensor is inserted between the magnetic scale and the cylindrical body and generates a pulse signal in response to the magnetic field formed by the magnet of the magnetic scale. A reference point sensor that generates a magnetic field detection signal in response to the magnetic field generated by the magnet in the cylinder, and a position sensor that receives the output signals of the position sensor and reference point sensor and generates a pulse signal of the position sensor based on the magnetic field detection signal of the reference point sensor. a calculation device that calculates the amount of movement of the moving device by counting, and each magnet of the moving device is arranged at a different position in the axial direction and the radial direction of the cylindrical body. encoder.