US 8,800,397 B2 · Positioning device

Abstract

Temperatures of a base, a support member, and a support member are measured, and amounts of linear expansion of the base, the support member, and the support member due to temperature differences from a reference temperature are computed. An amount of linear expansion of a ball screw with respect to the support member is measured. An amount of linear expansion of a lead of the ball screw is computed based on the sum of the aforementioned amounts of linear expansion, and an amount of rotation of the ball screw is adjusted from an amount of rotation of the ball screw at the reference temperature, to an amount of rotation of the ball screw, which corresponds to the amount of linear expansion of the lead at a predetermined temperature.

A positioning device, comprising:

a base;
a movable body that is supported so as to be allowed to reciprocate in a predetermined axial direction with respect to the base;
a ball screw that is engaged with the movable body, and that reciprocates the movable body;
a drive motor that is engaged with a first end of the ball screw, and that transmits rotative power to rotate the ball screw;
first support means that is fixed to a first fixed position of the base, and that supports a portion of the ball screw, the portion being near the first end of the ball screw, at a first reference position that is located at a predetermined distance from the first fixed position in the axial direction such that the portion of the ball screw is rotatable and immovable in the axial direction;
second support means that is fixed to a second fixed position of the base, and that supports a second end of the ball screw such that the second end is rotatable and movable in the axial direction;
distance detection means that is located at a given distance from an end face of the second end in an axial direction of the ball screw, that is fixed to the second support means at a second reference position that is located at a predetermined distance from the second fixed position in the axial direction, and that is able to detect a distance to the end face;
temperature detection means for detecting a temperature of the base, a temperature of the first support means, and a temperature of the second support means;
and
control means for controlling the drive motor, wherein
the control means stores
a base reference length that is a length of a portion of the base from the first fixed position to the second fixed position at a reference temperature,
a first support means reference length that is a length of a portion of the first support means from the first fixed position to the first reference position at the reference temperature,
a second support means reference length that is a length of a portion of the second support means from the second fixed position to the second reference position at the reference temperature, and
a ball screw reference length that is a length of a portion of the ball screw from the first reference position to the end face of the ball screw at the reference temperature, and
the control means obtains a ball screw actual length that is an actual length of the portion of the ball screw from the first reference position to the end face of the ball screw on the basis of
an amount of linear expansion of the base reference length, which is obtained through computation based on the base reference length and the detected temperature of the base that is detected by the temperature detection means,
an amount of linear expansion of the first support means reference length, which is obtained through computation based on the first support means reference length and the detected temperature of the first support means that is detected by the temperature detection means,
an amount of linear expansion of the second support means reference length, which is obtained through computation based on the second support means reference length and the detected temperature of the second support means that is detected by the temperature detection means, and
the detected distance that is detected by the distance detection means, and
the control means compensates a control amount of the drive motor based on the ball screw actual length and the ball screw reference length.

18 more elements

Description3,192 words

Summary1,019 words

#This application claims priority to Japanese Patent Application No. 2012-129638 filed on Jun. 7, 2012 the disclosure of which, including the specification, drawings and abstract, is incorporated herein by reference in its entirety.

#1. Field of the Invention

#The invention relates to a positioning device that is designed for, for example, a machine tool in which a ball screw is used, and that is able to more accurately compensate an error due to a temperature change.

Brief description of the drawings3 figures

#The foregoing and further objects, features and advantages of the invention will become apparent from the following description of an example embodiment thereof with reference to the accompanying drawings, wherein like numerals are used to represent like elements and wherein:

#FIG. 1 is a schematic view showing the overall configuration of a positioning device according to an embodiment of the invention;

#FIG. 2 is a sectional view of a screw portion of the positioning device at a reference temperature; and

Detailed description2,071 words

#Hereinafter, an embodiment of the invention will be described with reference to the accompanying drawings.

#As shown in FIG. 1, a positioning device 1 includes a base 2, a pair of guides 3 fixed to an upper portion of the base 2, and a movable body 4 that is supported by the guides 3 so as to be allowed to reciprocate in an X-axis direction. A ball screw 7 that is rotatably supported at respective ends thereof by a support member 5 and a support member 6 is engaged with the movable body 4, and a motor 8 fixed to the support member 5 is coupled to the ball screw 7. Thus, the positioning device 1 reciprocates the movable body 4 through the rotation of the motor 8.

#The positioning device 1 further includes a control device 30. The control device 30 includes a storage unit 301 that stores various data, a computation unit 302 that performs computation, a motor control unit 303 that controls the rotation of the motor 8, and the like. With the above-described configuration, the positioning device 1 controls the position of the movable body 4 in the X-axis direction by controlling the rotation of the motor 8.

Facts

Application

13/911,166Filed 6 Jun 2013

Priority

JP 2012-1296387 Jun 2012

Published

US 2013/0327167 A112 Dec 2013

Granted

12 Aug 2014

Term ends

6 Jun 2033

Estimated · how

20 years from earliest known nonprovisional domestic filing plus recorded patent term adjustment. Maintenance-fee lapses, terminal disclaimers and statutory extensions have not been checked. The continuity chain may be incomplete; this is not an enforceability determination.

Classification11 codes

B23Q 3/18
Devices holding, supporting, or positioning work or tools, of a kind normally removable from the machine: for positioning only
G05B 19/404
Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to…
G05B 2219/49206
Nc machine tool, till multiple: compensation temperature, thermal displacement, use measured temperature
G05B 2219/49207
Nc machine tool, till multiple: compensate thermal displacement using measured distance

Timeline

7 Jun 2012Priority claimedJP 2012-129638
6 Jun 2013Application filedUS 13/911,166
6 Jun 2013Assigned to Jtekt Corporationassignment of assignor's interest
12 Dec 2013PublishedUS 2013/0327167 A1
12 Aug 2014GrantedUS 8,800,397 B2
12 Oct 2026TodayWithin its term
6 Jun 2033Term endsEstimated

Positioning device

Life of this patent

Positioning device

Life of this patent

Life of this patent

Abstract

Drawings

Drawings

Claims1

Description3,192 words

Drawings

Classification11 codes

Life of this patent

Description3,192 words