JP5991671B2 - Feeder - Google Patents

Description

  The present invention relates to a feeding device that can prevent a ball screw shaft from swinging.

  2. Description of the Related Art Conventionally, a machine tool has been adopted that feeds a moving body such as a table in the direction of the ball screw shaft by rotating the ball screw shaft. In such a feeding device, the ball screw shaft is supported by a cradle from below for the purpose of suppressing the bending and swinging of the long ball screw shaft.

  And the conventional feeder as mentioned above is disclosed by patent document 1, for example.

Japanese Patent Laid-Open No. 5-301135

  However, in the above-described conventional feeding device, the contact portion of the cradle with the ball screw shaft is an arc-shaped recess according to the diameter of the ball screw shaft, so that the contact area between the ball screw shaft and the cradle increases. End up. As a result, if the ball screw shaft rotates, the frictional heat generated between the ball screw shaft and the arcuate recesses causes the ball screw shaft to thermally expand, and the ball screw shaft and the cradle may be worn.

  Therefore, this invention solves the said subject, and it aims at providing the feeder which can suppress the thermal elongation and wear of a ball screw shaft.

A feeding device according to a first invention for solving the above-described problems is as follows.
A ball screw shaft rotatably supported;
A moving body that is screwed onto the ball screw shaft and is fed in the direction of the ball screw shaft by rotation of the ball screw shaft;
A rotating body that is rotatably supported and prevents rolling of the ball screw shaft by rolling contact with the ball screw shaft;
Moving means for moving the rotating body between a contact position where the rotating body contacts the ball screw shaft and a retracted position where the rotating body retracts from the ball screw shaft ;
A rotational speed detection means for detecting the rotational speed of the ball screw shaft;
When the rotational speed detected by the rotational speed detection means is equal to or higher than the rotational speed at which the ball screw shaft swings, the drive of the moving means is controlled to move the rotating body to the contact position, Movement control for controlling the drive of the moving means to move the rotating body to the retracted position when the rotational speed detected by the rotational speed detecting means is less than the rotational speed at which the ball screw shaft swings. Means .

A feeding device according to a second invention for solving the above-described problems is as follows.
Position detecting means for detecting whether or not the rotating body is disposed at the contact position or the retracted position;
Rotation control means for stopping rotation of the ball screw shaft when the position detection means cannot detect the rotating body at the contact position or the retracted position.

  Therefore, according to the feeding device according to the present invention, the contact area between the ball screw shaft and the rotating body can be reduced by providing the rotating body capable of rolling contact with the ball screw shaft. It is possible to suppress thermal elongation and wear.

It is a schematic block diagram of the feeder which concerns on one Example of this invention. It is the II-II arrow sectional drawing of FIG.

  Hereinafter, a feeding device according to the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, bearing members 12a and 12b are provided on the left and right sides of the upper surface of the base 11, and a ball screw shaft 13 is rotatably supported between the bearing members 12a and 12b. ing. A moving body (ball screw nut) 14 is screwed onto the ball screw shaft 13.

  A motor 15 is provided on the outer side of the bearing member 12b in the ball screw axis direction. The motor 15 is provided with a detector (rotation speed detecting means) 16 for detecting the rotation speed and rotation angle of the motor 15, and the output shaft of the motor 15 is connected to the end of the ball screw shaft 13. Connected.

  Therefore, by driving the motor 15, the ball screw shaft 13 rotates, and the movable body 14 can be reciprocated in the ball screw shaft direction. At this time, the rotation number and rotation angle of the motor 15 are always detected by the detector 16. That is, the rotational speed of the motor 15 corresponds to the rotational speed of the ball screw shaft 13 and the moving speed of the moving body 14, and the rotational angle of the motor 15 corresponds to the moving position of the moving body 14. .

  Further, as shown in FIGS. 1 and 2, a cylinder 21 is provided below a ball screw shaft direction intermediate portion (hereinafter referred to as an intermediate position O) of the ball screw shaft 13. A piston rod 22 is supported on the cylinder 21 so as to be slidable in the vertical direction (the radial direction of the ball screw shaft 13).

  A roller bracket 23 is provided at the upper end of the piston rod 22, and columnar or cylindrical rollers (rotating bodies) 24 are rotatably supported on both sides of the roller bracket 23 in the width direction. ing. The rollers 24 are arranged such that their rotational axes are parallel to the rotational axis of the ball screw shaft 13.

  The cylinder 21, the piston rod 22, and the roller bracket 23 constitute moving means.

  Accordingly, by driving the cylinder 21, the piston rod 22 slides in the vertical direction, so that the roller 24 can be moved up and down in the ball screw shaft radial direction. As a result, the roller 24 moves between a contact position P1 that contacts the ball screw shaft 13 and a retreat position P2 that retreats from the ball screw shaft 13.

  At this time, the roller 24 arranged at the contact position P <b> 1 is in rolling contact with the ball screw shaft 13, thereby preventing the ball screw shaft 13 from swinging. Then, by bringing the roller 24 into rolling contact with the ball screw shaft 13, the frictional heat generated between them is reduced, so that the thermal expansion of the ball screw shaft 13 is suppressed, and the ball screw shaft 13 and Wear of the roller 24 is also suppressed.

  As shown in FIG. 1, switches (position detection means) 25 a and 25 b are provided above the cylinder 21 so as to be arranged in the vertical direction. These switches 25 a and 25 b are arranged along the vertical movement direction of the roller 24.

  That is, the upper switch 25a detects whether or not the roller 24 is disposed at the contact position P1, and when the roller 24 is disposed at the contact position P1, the switch 24a is turned on, and the roller 24 is in the contact position P1. If it is not arranged, it will be in an OFF state.

  On the other hand, the lower switch 25b detects whether or not the roller 24 is disposed at the retracted position P2. When the roller 24 is disposed at the retracted position P2, the switch 24b is turned on and the roller 24 is retracted. If it is not arranged, it will be in an OFF state.

  Further, a motor control unit (rotation control unit) 31 is connected to the motor 15 and the detector 16, and a cylinder control unit (movement control unit) 32 is connected to the cylinder 21 and the switches 25a and 25b. . And these control parts 31 and 32 are also mutually connected.

  The motor control unit 31 controls the drive (rotation) and stop of the motor 15, and the rotation speed and rotation angle of the motor 15 input from the detector 16, and the movement speed and movement position of the moving body 14 corresponding thereto. Is output to the cylinder control unit 32.

  On the other hand, the cylinder control unit 32 controls the lifting and lowering of the piston rod 22 in the cylinder 21 and stops the motor 15 based on the presence / absence of the roller 24 at the contact position P1 and the retracted position P2 input from the switches 25a and 25b. The command is output to the motor control unit 31.

  That is, when the switches 25a and 25b cannot detect the roller 24 at the contact position P1 or the retracted position P2, the cylinder control unit 32 outputs a motor 15 stop command to the motor control unit 31. It has become. In response to this, the motor control unit 31 immediately drives the motor 15 because the cylinder 21 and the switches 25a and 25b are out of order or there is a possibility of collision between the moving body 14 and the roller 24. To stop the rotation of the ball screw shaft 13 and the movement of the moving body 14.

  In addition, when the rotational speed of the ball screw shaft 13 (motor 15) detected by the detector 16 becomes equal to or higher than the dangerous rotational speed at which the ball screw shaft 13 swings, the motor control unit 31 A contact command for the roller 24 is output to the control unit 32. In response to this, the cylinder controller 32 immediately drives the cylinder 21 to bring the roller 24 into contact with the ball screw shaft 13 because there is a possibility that the ball screw shaft 13 may run around.

  On the other hand, when the rotational speed of the ball screw shaft 13 (motor 15) detected by the detector 16 becomes less than the critical rotational speed at which the ball screw shaft 13 swings, the motor control unit 31 A retraction command for the roller 24 is output to the control unit 32. In response to this, the cylinder controller 32 immediately drives the cylinder 21 and retracts the roller 24 from the ball screw shaft 13 on the assumption that there is no risk of the ball screw shaft 13 swinging.

  Next, the operation of the feeding apparatus according to the present invention will be specifically described with reference to FIG. In the following description, the case where the moving body 14 moves from one end side (the position of the solid line in FIG. 1) to the other end side (the position of the two-dot chain line in FIG. 1) of the ball screw shaft 13 will be described.

  First, the ball screw shaft 13 is rotated by driving the motor 15. As a result, the moving body 14 starts to move from one end side to the other end side of the ball screw shaft 13.

  In addition, at the initial stage of movement of the moving body 14 described above, since the rotation speed of the ball screw shaft 13 is less than the critical rotation speed, the roller 24 is disposed at the retracted position P2 by driving the cylinder 21. It is not in contact with the ball screw shaft 13.

  Next, the moving body 14 further moves toward the other end side of the ball screw shaft 13. At this time, when the moving body 14 is at a position away from the intermediate position O on the ball screw shaft 13 at one end side by a predetermined distance D or more, and the moving speed of the moving body 14 is equal to or higher than the predetermined moving speed. When the rotational speed of the ball screw shaft 13 is equal to or higher than the critical rotational speed, the cylinder 21 is driven. As a result, as the piston rod 22 rises, the roller 24 moves from the retracted position P2 toward the contact position P1. That is, the switch 25b changes from the ON state to the OFF state.

  Here, if the switch 25a does not detect the roller 24 even if a predetermined time has elapsed after the cylinder 21 is driven (when the switch 25a is not turned on), the cylinder 21 and the switch 25a are broken. The drive of the motor 15 is stopped because there is a possibility of having performed.

  On the other hand, when the switch 25a detects the roller 24 after a predetermined time has elapsed after the cylinder 21 is driven (when the switch 25a is turned on), the roller 24 is disposed at the contact position P1, and the ball screw It is in contact with the shaft 13. As a result, the dangerous rotational speed at which the ball screw shaft 13 swings is improved, and the ball screw shaft 13 is prevented from swinging.

  When the moving body 14 further moves toward the other end side of the ball screw shaft 13 and enters the predetermined distance D on the one end side, the cylinder 21 is driven. Thus, as the piston rod 22 is lowered, the roller 24 moves from the contact position P1 toward the retracted position P2. That is, the switch 25a changes from the ON state to the OFF state.

  Here, if the switch 25b does not detect the roller 24 even when a predetermined time has elapsed after the cylinder 21 is driven (when the switch 25b is not turned on), the moving body 14 and the roller 24 As a result, the motor 15 is stopped.

  On the other hand, when the switch 25b detects the roller 24 after a predetermined time has elapsed after the cylinder 21 is driven (when the switch 25b is turned on), the roller 24 is disposed at the retracted position P2, and the ball screw This means that the shaft 13 is completely detached.

  Next, after the moving body 14 has passed through the intermediate position O on the ball screw shaft 13 and is separated from the intermediate position O to the other end side by a predetermined distance D or more, the cylinder 21 is driven. As a result, as the piston rod 22 rises, the roller 24 moves from the retracted position P2 toward the contact position P1. That is, the switch 25b changes from the ON state to the OFF state.

  Here, if the switch 25a does not detect the roller 24 even if a predetermined time has elapsed after the cylinder 21 is driven (when the switch 25a is not turned on), the cylinder 21 and the switch 25a are broken. The drive of the motor 15 is stopped because there is a possibility of having performed.

  On the other hand, when the switch 25a detects the roller 24 after a predetermined time has elapsed after the cylinder 21 is driven (when the switch 25a is turned on), the roller 24 is disposed at the contact position P1, and the ball screw It is in contact with the shaft 13. As a result, the dangerous rotational speed at which the ball screw shaft 13 swings is improved, and the ball screw shaft 13 is prevented from swinging.

  When the rotational speed of the ball screw shaft 13 is less than the above-mentioned critical rotational speed, the ball screw shaft 13 is not swung, so that the roller 24 is retracted regardless of the moving position of the moving body 14. You may make it arrange | position to P2.

  Therefore, according to the feeding device according to the present invention, since the roller 24 capable of rolling contact with the ball screw shaft 13 is provided, the contact area between the ball screw shaft 13 and the roller 24 can be reduced. The thermal elongation and wear of the screw shaft 13 can be suppressed.

  Further, it is detected only whether or not the rotational speed of the ball screw shaft 13 is a dangerous rotational speed at which the ball screw shaft 13 swings, and the detected rotational speed is equal to or higher than the critical rotational speed. By bringing the roller 24 into contact with the ball screw shaft 13, the movement control of the roller 24 (drive control of the cylinder 21) can be simplified.

  Further, when the switches 25 a and 25 b cannot detect the roller 24, the rotation of the ball screw shaft 13 and the movement of the moving body 14 are stopped, thereby causing an inadvertent collision between the moving body 14 and the roller 24. Can be prevented in advance.

  The present invention can be applied to a feeder intended to reduce noise.

11 Base 12a, 12b Bearing member 13 Ball screw shaft 14 Moving body 15 Motor 16 Detector 21 Cylinder 22 Piston rod 23 Roller bracket 24 Roller 25a, 25b Switch 31 Motor control section 32 Cylinder control section P1 Contact position P2 Retraction position

Claims (2)

A ball screw shaft rotatably supported;
A moving body that is screwed onto the ball screw shaft and is fed in the direction of the ball screw shaft by rotation of the ball screw shaft;
A rotating body that is rotatably supported and prevents rolling of the ball screw shaft by rolling contact with the ball screw shaft;
Moving means for moving the rotating body between a contact position where the rotating body contacts the ball screw shaft and a retracted position where the rotating body retracts from the ball screw shaft ;
A rotational speed detection means for detecting the rotational speed of the ball screw shaft;
When the rotational speed detected by the rotational speed detection means is equal to or higher than the rotational speed at which the ball screw shaft swings, the drive of the moving means is controlled to move the rotating body to the contact position, Movement control for controlling the drive of the moving means to move the rotating body to the retracted position when the rotational speed detected by the rotational speed detecting means is less than the rotational speed at which the ball screw shaft swings. feeder, characterized in that it comprises a means. The feeding device according to claim 1 ,
Position detecting means for detecting whether or not the rotating body is disposed at the contact position or the retracted position;
And a rotation control unit that stops rotation of the ball screw shaft when the position detecting unit cannot detect the rotating body at the contact position or the retracted position.

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