JPH04315543A - Direct acting drive device - Google Patents

Abstract

PURPOSE:To provide a small and light direct acting drive device which provides generating force characteristic suitable for a direct acting drive device for positioning a bite to drive a bite as it overcomes a cutting back force. CONSTITUTION:A drive device comprises an electromagnet, a permanent magnet 4 disposed in the magnetic circuit of the electromagnet, an armature 3 attracted to the electromagnet or the permanent magnet 4, and leaf springs 6a and 6b energizing the armature 3 in a direction opposite to that of the attraction force of the permanent magnet 4. A drive force in a direction in which a bite is retracted is generated through the forces of the leaf springs 6a and 6b. In a state that the electromagnet is not energized, the attraction force of the permanent magnet 4 is balanced with the energizing forces of the leaf springs 6a and 6b, and when the moving part of a device is brought into a static rest state, there is no need for the flow of a current to the electromagnet.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear drive device, and is particularly suitable for a tool post feed device of a machine tool.

0002

[Prior Art] Parts that are cylindrical or spherical rotating bodies whose cross section is slightly deviated from a perfect rotating body, such as elliptical pistons for reciprocating engines and molds for aspherical lenses. is processed using a lathe or the like whose tool rest moves in synchronization with the rotation of the main shaft. In these fields, profiling lathes have been used in the past, in which a pre-made cam plate is rotated in synchronization with the main shaft, and the turret is moved by the cam plate for machining, but in recent years, NC control and machining In order to cope with higher speeds, research is progressing on devices that use actuators to drive the turret.

[0003] Figure 3 shows 1
A schematic perspective view showing the configuration of a linear drive device for positioning a tool for a conventional high-speed non-circular contour cutting NC lathe, which was described in p101 of the collection of papers from the 2nd Intelligent FA Symposium Lecture held in July 19989. In the figure, 1
1a, 11b, 11c, 11d are electromagnets, 5 is a tool drive shaft, 6a, 6b, 6c are leaf springs, 3 is a tool drive shaft 5
It is an armature that is fixed to and is attracted and driven by electromagnets 11a, 11b, 11c, and 11d.

Next, the operation will be explained. The cutting tool drive shaft 5 is supported by plate springs 6a, 6b, and 6c, and a cutting tool is provided at the tip thereof. Electromagnets 11a, 11
b, 11c and 11d are provided facing each other with the armature 3 in between, and 11a and 11b or 11c and 11d
By exciting the armature 3, the armature 3 is attracted, and the cutting tool drive shaft 5 fixed to the armature 3 moves in the direction of the arrow. By manipulating the current flowing through the electromagnets 11a and 11b or 11c and 11d, the cutting tool drive shaft 5 can be controlled to a desired position.

[0005]

[Problem to be solved by the invention] Since electromagnets can only generate force in one direction, in the conventional linear drive device for tool positioning using electromagnets, it is difficult to use the method of using electromagnets facing each other as described above. It had been taken. On the other hand, if we consider the force required to drive the tool positioning device, the cutting reaction force generated by the cutting process performed by the tool only occurs in one direction, so a large driving force is required in only one direction. It can be seen that it is sufficient to generate enough force to move the movable part of the device in the opposite direction.

[0006] As described above, the conventional linear drive device for positioning the cutting tool has the problem that the originally required driving force characteristics and the current generated force characteristics do not match, resulting in a lot of waste.

The present invention was made in order to solve the above-mentioned problems, and provides a linear drive device that can obtain force generation characteristics suitable for, for example, a linear drive device for positioning a cutting tool, and can be made smaller and lighter. The purpose is to obtain.

[0008]

[Means for Solving the Problems] The direct drive device of the present invention includes an electromagnet, a permanent magnet disposed in a magnetic circuit of the electromagnet, a movable iron core attracted to the electromagnet or the permanent magnet,
and an elastic body that urges the movable iron core in a direction opposite to the attractive force of the permanent magnet.

[0009]

[Operation] In the linear drive device of the present invention, the generation of driving force, which was conventionally performed by a pair of opposing electromagnets, can be
The driving force in one direction is generated by an elastic body, and can be generated using only one electromagnet, so that the other electromagnet and its accompanying device can be omitted. In addition, for example, a permanent magnet that generates an attractive force that balances the elastic body when the electromagnet is not energized is inserted into the electromagnet's magnetic circuit to counteract the force generated by the elastic body, so that the movable parts of the device are When it is stationary, there is no need to pass current through the electromagnet.

0010

【Example】

Example 1 An example of the present invention will be described below with reference to the drawings. Figure 1 shows high-speed non-circular contour cutting N using the linear drive device of this invention.
It is a partially cutaway front view showing the configuration of a linear drive device for positioning a cutting tool for a C lathe, in which 1 is a coil, 2a and 2b are cylindrical iron cores forming a magnetic circuit, and 3 is a coil 1. A armature of a movable iron core that is attracted by energizing the
4 is a permanent magnet inserted in the magnetic circuit, 5 is a cutting tool drive shaft, 6a and 6b are elastic bodies, in this case leaf springs, 7 is a position sensor that detects the amount of movement of the cutting tool driving shaft 5, 8 is a cutting tool,
9a and 9b are bases which are fixed parts.

Next, the operation will be explained. The cutting tool drive shaft 5 is supported by plate springs 6a and 6b, and a cutting tool 8 is provided at the tip thereof. Iron cores 2a, 2b, armature 3 and permanent magnet 4 which are magnetic circuits that constitute an electromagnet
The magnetic flux generated by the permanent magnet 4 acts on the armature even when no current is flowing through the coil 1, and the cutting tool drive shaft 5 receives the attractive force acting on the armature 3 due to this magnetic flux and the force generated by the leaf springs 6a and 6b. It stands still at the position where the reaction force is balanced. If a current is passed through the coil 1 in a direction that strengthens the magnetic flux generated by the permanent magnet 4, the armature 3 will be further attracted, and a driving force will be generated in the cutting tool drive shaft 5 in the direction of protruding the cutting tool, and this driving force will be passed through the coil 1. It increases as the current increases. Also, if the current is passed in the opposite direction to weaken the magnetic flux caused by the permanent magnet 4, the blade springs 6a and 6b will be attached to the cutting tool drive shaft 5.
A driving force is generated in the direction of retracting the cutting tool 8 due to the reaction force, and this driving force in the opposite direction continues until the magnetic flux generated by the permanent magnet 4 is completely canceled out, that is, until the magnetic flux acting on the magnetic circuit disappears. , increases as the magnitude of the current in the opposite direction increases. By detecting the movement of the tool drive shaft 5 with the position sensor 7 and manipulating the current flowing through the coil 1, the tool drive shaft 5 can be controlled to a desired position.

From the above explanation, the linear drive device according to this embodiment has the ability to reach the attraction force due to the maximum current that can be passed through the coil 1 of the electromagnet in the direction in which the cutting tool 8 is pushed out, and the permanent magnet 4 in the direction in which the cutting tool 8 is retracted. It can be seen that it is possible to generate a driving force up to the magnitude of the reaction force of the plate springs 6a, 6b in a state where the magnetic flux is canceled. The characteristic diagram in FIG. 2 shows the range of generation of this driving force together with the amount of protrusion of the cutting tool 8. In the figure, the vertical axis is the range of generation of driving force,
The horizontal axis is the amount of protrusion, and the amount of protrusion is defined as the free position of the leaf springs 6a and 6b when no current is flowing, which is the 0 position.
The operating limit of Amateur 3 is represented by S. The maximum current value mentioned above is expressed as i+max, and the current value in the opposite direction balanced with the permanent magnet is expressed as i-max. The range in which the driving force is generated changes depending on the amount of protrusion and the current, and when the amount of protrusion is 0, it is from F0+ to F0-, and when the amount of protrusion is S, it is from FS+ to FS-. The driving force required to move the cutting tool 8, cutting tool drive shaft 5, and armature 3 at high speed is the same force in both positive and negative directions, but when performing the above movement while cutting, Since processing reaction force acts in the direction, that is, in the direction in which the cutting tool 8 is pushed out, it is necessary to compensate for this. As shown in Figure 2,
In the linear drive device of the present invention, in the movable range of the cutting tool, that is, the amount of protrusion from 0 to S, in the positive direction, that is, in the cutting tool ejection direction, the driving force is a combination of the force necessary to move the movable part and the processing reaction force. The force range is set by adjusting the magnitude of the attractive force due to the magnetic flux generated by the permanent magnet 4 so that the force is generated in the negative direction, that is, in the direction of retracting the cutting tool, so that the driving force necessary to move the movable part is generated. There is. In this way, in this embodiment, the generation of driving force in one direction is performed by the plate spring 6a.
, 6b, it is possible to obtain generation force characteristics suitable for a linear drive device for positioning a cutting tool, and generation of driving force, which was conventionally performed by a pair of opposing electromagnets, can be performed with only one electromagnet. The other electromagnet and its associated equipment can be omitted. Therefore, the device can be made smaller and lighter.

Furthermore, as shown in FIG. 2, in the direct drive device of the present invention, by appropriately selecting the spring constants of the leaf springs 6a and 6b, the attractive force generated by the permanent magnet when the current is 0 can be suppressed by the leaf springs as much as possible. By canceling them out, the current flowing through the coil 1 can be reduced when positioning the tip of the cutting tool 8 when cutting is not performed, and power consumption can be reduced.

[0014]

As described above, the direct drive device according to the present invention includes an electromagnet, a permanent magnet disposed in the magnetic circuit of the electromagnet, a movable core attracted to the electromagnet or the permanent magnet, and the movable core. is composed of an elastic body that biases in the opposite direction to the attractive force of the permanent magnet, and the elastic body generates driving force in one direction. Good force generation characteristics can be obtained, and the device can be made smaller and lighter.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway front view showing the configuration of a linear drive device for positioning a cutting tool according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a driving force generation range of a linear drive device according to an embodiment of the present invention.

FIG. 3 is a schematic perspective view showing the configuration of a conventional linear drive device.

[Explanation of symbols]

1 Coil 2a Cylindrical iron core 2b Cylindrical iron core 3 Amateur moveable iron core 4 Permanent magnet 6a Elastic plate spring 6b Elastic plate spring

Claims (1)

[Claims] Claim 1: An electromagnet, a permanent magnet disposed in a magnetic circuit of the electromagnet, a movable core that is attracted to the electromagnet or the permanent magnet, and a movable core that is biased in a direction opposite to the attractive force of the permanent magnet. Direct drive device with elastic body.