JPH0546088Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to a positioning device for a numerically controlled machine in which a rotating shaft such as a feed screw is rotated by the drive of a motor to feed a moving body such as a table in a specified direction.

[Conventional technology]

Conventionally, in this type of device, an electromagnetic clutch and an electromagnetic brake are arranged between the output shaft of the motor and the feed screw, and when moving the tail, the electromagnetic brake is turned off and the electromagnetic clutch is turned on to control the output shaft of the motor. Rotation is transmitted to the feed screw via an electromagnetic clutch.

When the table is moved, the output pulse of the encoder driven by the rotation of the feed screw is fed back to the comparator section of the controller as a table feedback signal. When stopping the table, the electromagnetic clutch is turned off to cut off power transmission between the motor and the feed screw, and at the same time, the electromagnetic brake is turned on to forcibly stop the rotation of the feed screw.

[Problem that the invention attempts to solve]

When the table is stopped, if the electromagnetic brake is applied and the electromagnetic clutch is released,
Due to the inertia of the feed shaft, the brake plate of the electromagnetic brake is slightly displaced from the brake surface.
To prevent this, even when a toothed electromagnetic brake is used, an error occurs in the engagement state of the brake plate with the brake surface when the brake is applied, resulting in variations in the positioning accuracy of the table. The object of the present invention is to eliminate the above-described defect by ensuring that the teeth of the brake plate and the grooves on the brake surface mesh accurately at a predetermined rotational angle when the brake is applied.

[Means to solve problems]

In order to achieve the above object, the present invention sends the movable body 4 in a predetermined direction by the rotation of the rotary shaft 2 driven by the motor 34, and by the rotation of the slit plate 40 accompanying the rotational movement of the rotary shaft 2. A brake plate 12 with teeth and a brake surface that engages with the toothed brake plate 12 when the amount of movement of the moving body 4 corresponding to the amount of output pulses of a pulse encoder that outputs a pulse signal matches the set target value. In the device for forcibly stopping the rotation of the rotary shaft 2 by operating a tooth electromagnetic brake, the number of slits in the encoder plate 40 of the pulse encoder and the teeth 4 of the brake plate 12 of the tooth electromagnetic brake are
The ratio with the number 6 is set to 1:1.

[Effect]

When the rotary shaft 2 is rotated by the drive of the motor 34, the movable body 4 moves in a predetermined direction.

When the amount of movement of the moving body 4 corresponding to the set target value and the amount of output pulses of the pulse encoder match,
A brake-on signal is supplied to the tooth electromagnetic brake, and the brake plate 12 of the tooth electromagnetic brake comes into close contact with the brake surface by magnetic force, and at this time, the teeth 46 formed between the brake plate 12 and the brake surface
The grooves 48 are engaged with each other, and the rotating shaft 2 is forcibly stopped. Number of slits in slit plate 40 of pulse encoder and brake plate 1 of tooth electromagnetic brake
Since the teeth of No. 2 correspond to each other in a 1:1 ratio, the teeth electromagnetic brake engages accurately in response to the brake-on signal, and the stopping rotation angle of the rotary shaft 2 can be controlled with high precision.

〔Example〕

The configuration of the present invention will be described below with reference to embodiments shown in the accompanying drawings.

In FIG. 1, reference numeral 2 denotes a rotating shaft consisting of a feed screw of a numerically controlled machine tool or an automatic drafting machine, etc. As the rotating shaft 2 rotates, a movable body 4 consisting of a table etc. that is screwed together with the rotating shaft 2 is rotated. It is configured to move in a straight line direction along 2. Reference numeral 6 denotes a case fixed to the fuselage, on which shafts 8 and 10 are rotatably supported via ball bearings (not shown). Reference numeral 12 denotes a disc-shaped brake plate loosely fitted to the shaft body 8, and a holder disc 16 formed on the shaft body 8 via a known ring-shaped leaf spring 14.
are connected by known means. The brake plate 12 faces a brake surface of a stator 18 that is fixed to the shell 6. A coil 20 is built into the stator 18 . The holder plate 16, leaf spring 14, brake plate 12, stator 1
8 constitutes a known tooth electromagnetic brake.
Reference numeral 22 denotes a disc-shaped clutch plate, which is connected to a holder disc 26 formed on the shaft body 8 by known means via a ring-shaped leaf spring 24. The clutch plate 22 faces a rotor 28 fixedly attached to the shaft 10. 30 is a stator for the clutch fixedly installed on the mechanism 6, and a coil 3 is connected to this stator.
2 is built-in. The shaft 10 is connected to the output shaft of a geared motor 34, and the shaft 8 is connected to the rotating shaft 2 by a coupling 34. The stator 30, coil 32, rotor 28, clutch plate 22, leaf spring 24 and holder plate 26 constitute a known electromagnetic clutch. 38 is machine 6
The central portion of a known slit plate 40 rotatably supported by the casing 38 is connected to the shaft 8. A light emitting element 42 and a light receiving element 44 located on both sides of the slit plate 40 for reading the slit pattern of the slit plate 40 are supported by the casing 38. In this embodiment, a slit pattern is formed on the slit plate 40 so that the light receiving element 44 outputs 50 pulses when the slit plate 40 rotates once. The output end of the pulse encoder is connected to the counter 58 of the controller.
The motor 34 and the electromagnetic clutch/brake coils 32, 20 are connected to a drive control circuit 68 of the controller. On the surface of the brake plate 12 facing the brake surface, 50 teeth 46 are formed at equal pitches along a circular line centered on the rotation center of the brake plate 12, corresponding to the number of slits. , a tooth groove 48 for meshing with the teeth 46 is provided on the brake surface,
The same number of teeth as the teeth 46 are formed. That is, the number of slits on the encoder plate 40 and the number of teeth 4 on the brake plate 12
The ratio of the numbers 6 is set to 1:1. In the above embodiment, the amount of movement of the movable body 4 due to one revolution of the rotating shaft 2 is set to 5 mm, and the minimum reading value of the pulse encoder is set to 0.1 mm.

Next, the operation of the embodiment will be explained.

By operating the keyboard 50 or by inputting the contents of an input medium such as a magnetic tape in which a table positioning program is stored into an input device (not shown), the target value setting circuit 52 is inputted to one of the movable bodies 4.
Enter one or more target value information. In addition, the deceleration point and overshoot correction amount are entered from the keyboard 50 or the program input device into the deceleration point setting circuit 54 and the overshoot correction amount setting circuit 5, respectively.
Enter 6. When the first positioning point of the moving body 4 is set to 100 mm, the deceleration distance is set to 20 mm, and the overshoot amount is set to 0.5 mm, and the value of the counter 58 connected to the output end of the pulse encoder is reset to zero, the target value When 100mm is set in the register 60, the difference by the comparator 62 becomes +
10000, the forward/reverse rotation determining circuit 64 determines normal rotation, a motor normal rotation signal is input to the drive section control circuit 68 via the output buffer 66, and a normal rotation command is output from the circuit 68 to the motor 34. Simultaneously with this normal rotation command, current is supplied from the drive unit control circuit 68 to the coil 32 of the electromagnetic clutch, and the clutch plate 22 is attracted toward the rotor 28 by the magnetic force of the coil 32, causing the leaf spring 24 to bend and thereby causing the clutch plate to 22
is in close contact with the rotor 28, and the driving force of the motor 34 is transmitted to the rotating shaft 2. The movable body 4 moves by the rotation of the rotary shaft 2, and at this time, the encoder plate 40 rotates and the output end of the pulse encoder outputs pulses, which are counted by the counter 58.
When the value of the counter 58 reaches 80 mm, the deceleration point detection circuit 70 detects the deceleration point, and based on the detection signal of the detection circuit 70, the output buffer 66 supplies a motor low speed command to the drive unit control circuit 68, and the drive unit Control circuit 68 decelerates motor 34. As a result, the output shaft of the motor 34 rotates slowly, and after that, the stop position detection circuit 72 detects the moving body 4.
The stop position, that is, 0.5 mm (overshoot amount) before the target value is detected, and based on this detection signal, the output buffer 66 is activated by the drive section control circuit 6.
A motor stop command is output to 8. In response to this command, the drive unit control circuit 68 cuts off the power to the motor 34 and at the same time cuts off the power to the coil 32, disconnects the electromagnetic clutch, and cuts off the power transmission path between the motor 34 and the rotating shaft 2. Further, the drive section control circuit 68 turns off the electromagnetic clutch and simultaneously energizes the coil 20 of the electromagnetic brake in response to a motor stop command from the output buffer 66. As a result, the brake plate 12 is attracted to the brake surface of the stator 18 by magnetic force, and the brake plate 12 is attracted to the brake surface of the stator 18 by magnetic force.
The second tooth 46 meshes with the groove 48 on the brake surface, the rotating shaft 8 is locked, and the positioning of the movable body 4 is completed. In this case, the teeth 46 of the brake plate 12 are in one-to-one correspondence with the slit pattern of the encoder plate 40, so that the brake on signal of the drive unit control circuit 68 causes the teeth 46 of the brake plate 12 to
meshes precisely with the groove 48 on the brake surface side corresponding to the brake-on signal. Therefore, it is possible to position the moving body with high precision without variations in positioning accuracy.

〔effect〕

As mentioned above, the present invention is based on the number of slits in the pulse encoder that converts the movement of the moving object into pulse signals and feeds it back to the comparison section of the controller, and the teeth on the brake plate of the electromagnetic brake to stop the movement of the moving object. Since the ratio with the number of brakes is set to 1:1, the brake-on signal based on the feedback pulse of the pulse encoder causes the teeth and grooves of the electromagnetic brake corresponding to the signal to mesh with each other, thereby stopping the moving object. There is an effect that positioning can be performed with high accuracy without variation.

[Brief explanation of the drawing]

FIG. 1 is an explanatory sectional view, and FIG. 2 is an explanatory block diagram. 2...Rotating axis, 4...Moving body, 6...Machine,
8, 10... Shaft body, 12... Brake plate, 14...
... Leaf spring, 16 ... Holder plate, 18 ... Stator, 20 ... Coil, 22 ... Clutch plate, 24
...Plate spring, 26...Holder plate, 28...Rotor, 30...Stator, 32...Coil, 34...
... Motor, 36 ... Coupling, 38 ... Casing, 40 ... Slit plate, 42 ... Light emitting element, 44 ... Light receiving element, 46 ... Teeth, 48 ...
groove.

Claims (1)

[Scope of utility model registration request] A pulse encoder that sends a movable body 4 in a predetermined direction by the rotation of a rotary shaft 2 driven by a motor 34, and outputs a pulse signal by the rotation of a slit plate 40 accompanying the rotational movement of the rotary shaft 2. When the amount of movement of the moving body 4 corresponding to the amount of output pulses matches the set target value, the toothed brake plate 12
In this device, the number of slits in the encoder plate 40 of the pulse encoder is A positioning device for a numerically controlled machine, characterized in that the ratio of the number of teeth 46 of the brake plate 12 of the tooth electromagnetic brake is set to 1:1.