JP2009092183A - Linearly moving device and its abnormality determining device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means for early determining a circulation abnormality of a rolling element circulating in a circulating passage. <P>SOLUTION: A metal detecting sensor 16 detecting the approach of a ball 9 circulating in the circulating passage 14 is arranged in a part for forming a direction changing passage 12 of a resin end cap 11 constituting a part of the circulating passage 14 of a linear guide device 1. A passing time interval of the ball 9 is detected by the metal detecting sensor 16. When the passing time interval is an abnormality determining passing period or longer, the occurrence of the circulation abnormality is determined. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a linear motion device used in a machine tool such as a linear guide device and a ball screw device, a precision machine, a semiconductor manufacturing device, a feed mechanism of a mechanical device such as an injection molding machine, and the like and an abnormality determination device thereof.

  A linear guide device as a linear motion device is configured by supporting a slider on a rail so that it can move linearly via rolling elements such as balls circulating in a circulation path. If an abnormal circulation such as a clogging phenomenon occurs, the sliding resistance of the rolling element increases and excessive force acts on the end cap where the direction change path is formed, causing the end cap to break. Therefore, there is a possibility of fatal damage that the function as a linear motion device cannot be performed, and means for detecting an abnormality before the fatal damage is required.

As a conventional linear guide device abnormality determination device, a return path provided with a linear guide device on a slider, a direction change path provided on an end cap, a rail track groove provided on a rail, and a slider track groove provided on a slider, A plurality of balls are loaded in each of four circulation paths communicating with a load path formed opposite to each other, and a slider that linearly moves the rail is supported by a ball that rolls along the load path of the circulation path. In order to detect abnormalities in the linear guide device, strain gauges are attached to the end faces of a total of eight locations on the outer walls of the direction change paths constituting the respective circulation paths of the end caps attached to the front and rear ends of the slider moving direction. The bridge circuit formed by the above is pasted, the deformation amount of the end face of the end cap is detected by each bridge circuit, and the voltage signal from either bridge circuit is detected. When There has changed, by detecting that would end cap is damaged, it has stopped the operation of the linear guide device (e.g., see Patent Document 1.).
Japanese Patent Laying-Open No. 2005-42785 (6th page, paragraphs 0032-0036, 8th page, paragraphs 0051-0058, FIGS. 1 and 6)

  However, in the above-described conventional technology, since the abnormality in the circulation path is detected by detecting the deformation of the outer wall of the direction change path formed in the end cap, the sliding resistance increased due to the circulation abnormality. When the abnormality can be detected, the circulation abnormality has progressed considerably and is insufficient to prevent fatal damage to the linear guide device. There is a problem that.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide means for early determination of abnormal circulation of rolling elements circulating in a circulation path.

  In order to solve the above problems, the present invention provides a fixed body, a movable body supported by the fixed body through a plurality of metal rolling elements so as to be movable, and a circulation path through which the rolling elements circulate. In the linear motion device provided, a metal detection sensor that detects an approach of the rolling element circulating in the circulation path is provided in a resin member that constitutes a part of the circulation path, and the metal detection sensor is used to detect the rolling element. It is characterized by detecting a passage time interval.

  Thus, the present invention uses the fact that the passage time interval shifts to the long time side when a circulation abnormality occurs in the circulation path, and directly detects the circulation abnormality before the sliding resistance increases by the metal detection sensor. It is possible to obtain an effect that it can be detected early and surely that a circulation abnormality has occurred in the circulation path.

  Embodiments of a linear motion device and its abnormality determination device according to the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view illustrating a linear guide device according to an embodiment, and FIG. 2 is a block diagram illustrating an abnormality determination device according to the embodiment.
In FIG. 1, 1 is a linear guide device as a linear motion device.
Reference numeral 2 denotes a rail as a fixed body of the linear motion device, which is a long columnar member made of a steel material such as alloy steel, and has an upper surface for fixing the rail 2 to a base of a mechanical device or the like. A plurality of rail mounting holes 3 which are stepped bolt holes are provided at a predetermined pitch.

Reference numeral 5 denotes a rail track groove as a rolling element guide surface of the fixed body, which is a groove having an arcuate cross section formed along the longitudinal direction of both side surfaces of the rail 2.
Reference numeral 6 denotes a slider as a moving body of the linear motion device, which is a bowl-shaped member having a substantially U-shaped cross-section made of a steel material such as alloy steel, and has an attachment screw hole 7 provided on the upper surface thereof. The moving table or the like of the mechanical device is fastened with a bolt or the like using the mounting screw hole 7.

Reference numeral 8 denotes a slider raceway groove as a rolling element guide surface of the moving body, which is a groove having an arcuate cross section provided inside the sleeve walls 6 a of the slider 6 so as to face the rail raceway groove 5.
Reference numeral 9 denotes a ball as a rolling element of the linear motion device, which is a sphere made of a steel material such as alloy steel.
A return path 10 has a diameter larger than the diameter of the ball 9 for circulating the ball 9 formed on the sleeve wall 6 a of the slider 6, and the slider 6 moves in the moving direction of the slider 6 (referred to as the slider moving direction). Is provided corresponding to each slider raceway groove 8.

Reference numeral 11 denotes an end cap, which is made of a resin material or the like, and is disposed at the front and rear ends of the slider 6 in the slider moving direction.
Reference numeral 12 denotes a direction change path provided on the slider 6 side of the sleeve portion 11a of the end cap 11, and a load path formed by the slider raceway groove 8 and the rail raceway groove 5 arranged opposite to each other and a return path 10 of the slider 6. Are respectively provided in correspondence with the respective load paths, and have a function of guiding the balls 9 and turning their circulation directions.

Both ends of the load path are connected to each other by a communication path formed by the direction change path 12 of the end cap 11 and the return path 10 of the slider 6 to form a circulation path 14 of the linear guide device 1. A plurality of balls 9 are loaded on the path 14.
Further, as the slider 6 moves, the ball 9 circulates in the circulation path 14, and the ball 9 rolling on the load path supports the load applied to the slider 6 in a reciprocating manner. It is supported so that it can reciprocate linearly along the direction. Thereby, the linear guide apparatus 1 functions as a linear motion apparatus.

In the linear guide device 1 of the present embodiment, two circulation paths 14 are formed on one side, and four circulation paths 14 are formed on both sides, and end caps 11 are provided as resin members constituting a part of each circulation path 14. Yes.
Reference numeral 16 denotes a metal detection sensor, which is an inductive or magnetic gap sensor that detects the presence of metal, and the sensor output varies depending on the distance from the metal to be detected (in this embodiment, the ball 9). It changes and the approach of the ball 9 can be detected.

Further, the metal detection sensor 16 is formed on the end surface of the portion serving as the wall surface of the direction change path 12 of the sleeve portions 11a on both sides of the resin end cap 11 arranged at the front end portion of the slider 6 in the slider moving direction. Each is attached to a bottomed hole or the like, and detects the passage of the ball 9 moving along the direction change path 12 of each of the four circulation paths 14.
In FIG. 1, the metal detection sensor 16 of the present embodiment is arranged in a rear part, one at a site to be the direction change path 12 of the circulation path 14 on the lower side of each sleeve 11 a of the end cap 11 on the front side. A total of four are attached to the end cap 11 on the side, one at each of the portions that become the direction change paths 12 of the circulation path 14 on the upper side of each sleeve portion 11a.

Reference numeral 18 denotes a lead wire, which has a function of guiding the sensor output signal of each metal detection sensor 16 to an abnormality determination device 20 such as a personal computer shown in FIG.
In FIG. 2, reference numeral 21 denotes a control unit of the abnormality determination device 20, which controls each unit in the abnormality determination device 20 to execute abnormality determination processing and the like and also controls data communication and the like.
A storage unit 22 stores a program executed by the control unit 21, various data used for the program, a processing result by the control unit 21, and the like.

A clock unit 23 includes a frequency generator having a crystal oscillator and the like, a memory storing a calendar, etc., and counts elapsed time based on the generated frequency and outputs the current date and time to the control unit 21. It has a function to do.
A display unit 24 includes a display screen such as an LCD, and has a function of displaying a warning screen or the like at the time of determining a circulation abnormality.

An input unit 25 includes a keyboard, a mouse, and the like, and is used to calculate various set values and normal passage periods from an operator in charge of the mechanical device in which the linear guide device 1 is incorporated. It has a function of accepting input of specification values, parameters for threshold setting, and the like.
An alarm unit 26 includes a buzzer, a speaker, and the like, and has a function of issuing an alarm by a buzzer sound or an electronic sound when an abnormality occurs.

Reference numeral 30 denotes a driving device, which includes a motor for driving a ball screw device (not shown) and the like, and has a function of transmitting the moving speed of the slider 6 of the linear guide device 1 to the control unit 21 of the abnormality determination device 20 in real time. is doing.
In the storage unit 22 of the abnormality determination device 20, the revolution speed during normal operation of the ball 9 is obtained based on the geometric relationship of the linear guide device 1 and the moving speed of the slider 6 acquired from the driving device 30. Based on the sensor output signal from the metal detection sensor 16, the passage time interval between the adjacent balls 9 passing through the direction change path 12 of the circulation path 14 is detected, and this passage time interval becomes equal to or greater than the abnormality determination passage period. Sometimes, an abnormality determination processing program having a function of determining a circulation abnormality in the circulation path 14 and notifying a warning to a person in charge of operation by the display unit 24 or the alarm unit 26 is stored in advance. Each function means as hardware of the abnormality determination device 20 of the present embodiment is formed by the steps of the abnormality determination processing program executed by.

The storage unit 22 is preset with a passage detection threshold (see a solid line indicated by a symbol K in FIG. 4) for detecting the passage of one ball 9 based on a sensor output signal from the metal detection sensor 16. Stored.
As the passage detection threshold of this embodiment, a voltage in the range of 30% to 50% of the peak voltage of the sensor output signal from the metal detection sensor 16 (40% in this embodiment) is set. .

Further, the storage unit 22 stores an abnormal ball interval as an abnormal rolling element interval for calculating an abnormality determination passage period when determining an abnormal circulation of the ball 9 circulating in the circulation path 14 during operation of the linear guide device 1. Are preset and stored.
The abnormal ball interval of the present embodiment is a length obtained by adding the diameter of the ball 9 to the maximum value of the allowable dimension range of the sum of the gaps (referred to as the total gap) set between the balls 9 loaded in each circulation path 14. The length obtained by multiplying the length by a certain magnification is stored.

When a spacer made of resin or the like is inserted between the balls 9 to prevent the balls 9 from coming into direct contact with each other, the maximum value of the total gap is spaced by the diameter of the balls 9 and the spacers. A length obtained by multiplying the length of the ball 9 by a certain magnification is stored as the abnormal ball interval.
The constant magnification is set to a value in the range of 1.0 or more and 1.2 or less (1.1 in this embodiment).

In the following, the abnormality determination process of the present embodiment will be described according to the steps indicated by S using the flowchart shown in FIG.
When a person in charge of operating the mechanical device turns on the power to the mechanical device and the abnormality determination device 20 at the start of work or the like, the abnormality determination processing program stored in the storage unit 22 of the abnormality determination device 20 is automatically started.

S1, when the abnormality determination processing program is activated, the control unit 21 waits for the arrival of the moving speed exceeding “0” of the slider 6 from the driving device 30, and when the moving speed is received from the driving device 30, The process proceeds to step S2.
If the moving speed is not received, the standby is continued.
S <b> 2, the control unit 21 that has received the moving speed from the driving device 30 reads out the abnormal ball interval stored in the storage unit 22, and relates to the moving speed Vs of the slider 6 and the rolling shown in the equation (1). The revolution speed Vb of the ball 9 is calculated based on the geometric relation, that is, the geometric relation that the revolution speed Vb is half of the movement speed Vs.

Vb = Vs / 2 (1)
Then, the control unit 21 calculates the abnormality determination passing period by dividing the read abnormal ball interval by the calculated revolution speed.
In S3, the control unit 21 that has calculated the abnormality determination passage period reads the passage detection threshold value stored in the storage unit 22, and the clock unit 23 causes the sensor output signal of the metal detection sensor 16 to exceed the passage detection threshold value when it rises. From this time, the time until the value of the next sensor output signal rises to the passage detection threshold or more is measured to detect the passage time interval (see FIG. 4).

When the detected passage time interval is equal to or greater than the abnormality determination passage period, the control unit 21 that has detected the passage time interval determines that a circulation abnormality has occurred in the circulation path 14 and proceeds to step S5.
If the passage time interval is less than the abnormality determination passage period, it is determined that the operation is normal, the process returns to step S1, and the above abnormality determination is continued.

  S5, the control unit 21 that has determined that a circulation abnormality has occurred in the circulation path 14, displays a message that a circulation abnormality has occurred in the circulation path 14, a position of the circulation path 14 that has been determined to be a circulation abnormality, and the like. A screen is displayed on the display unit 24, a buzzer sound or a beep sound is generated from the alarm unit 26, a warning is given to an operator or the like, and a stop command is transmitted to the drive device 30 to operate the linear guide device 1. Stop.

  As described above, in the abnormality determination process of the present embodiment, the metal detection sensor 16 directly detects the passage time interval of the ball 9 moving on the direction change path 12, so that a circulation abnormality such as a clogging phenomenon occurs in the circulation path 14. By using the fact that the passage time interval shifts to the long time side, the circulation abnormality before the sliding resistance increases is directly detected, and the circulation abnormality has occurred at an early stage, and It can be determined reliably, and fatal damage such as breakage of the end cap 11 accompanying increase in sliding resistance can be prevented in advance.

  In addition, the time interval of the ball 9 detected by the metal detection sensor 16 is monitored while calculating the abnormality determination passage period using the geometric relationship regarding the rolling and the moving speed of the slider 6. Thus, it is possible to detect an abnormality in the passage time interval in the entire stroke range during operation including acceleration / deceleration, and to quickly and reliably determine that a circulation abnormality has occurred in the circulation path 14.

Furthermore, since the metal detection sensor 16 of the present embodiment is an inductive or magnetic sensor, it is possible to detect metal via resin, and an opening is provided in the direction change path 12 of the end cap 11. In addition, the passage time interval of the ball 9 can be detected.
As described above, in this embodiment, a metal detection sensor for detecting the approach of a ball circulating in the circulation path is provided on the resin end cap that constitutes a part of the circulation path of the linear guide device. By detecting the passage time interval of the ball by the sensor, when the circulation abnormality such as clogging occurs in the circulation path, the sliding resistance is utilized by shifting the passage time interval to the long time side. It is possible to detect the circulatory abnormality before the increase in the metal directly with the metal detection sensor, and to quickly and surely determine that the circulatory abnormality has occurred in the end cap. Can be prevented.

  In addition, when determining abnormal circulation of the ball circulating in the circulation path, the abnormal ball interval for calculating the abnormality determination passage period is stored, and the abnormal ball interval is expressed as a geometric relationship with rolling, Divide by the revolution speed of the ball calculated based on the moving speed of the slider to calculate the abnormality determination passage period, and the ball passage time interval detected by the sensor output signal of the metal detection sensor is calculated as the calculated abnormality determination passage period. Comparing and determining that a circulation abnormality has occurred in the circulation path when the detected passage time interval is equal to or greater than the abnormality determination passage period, the entire stroke range during operation including acceleration / deceleration in the movement of the slider It is possible to detect an abnormality in the passage time interval at, and to quickly and reliably determine that a circulation abnormality has occurred in the circulation path.

In the above embodiment, the linear guide device using a ball as a rolling element has been described as an example. However, the same effect can be obtained in a linear guide device using a roller as a rolling element.
In this case, the rolling element guide surface of the rail that forms the load path and the rolling element guide surface of the slider are composed of the rail raceway surface on which the roller rolls and the slider raceway surface, and the direction change path intersects three-dimensionally at the end cap. The end caps arranged at the front and rear end portions in the slider moving direction may be provided with a metal detection sensor for detecting the passage time interval of the rollers passing through the direction change paths on the side close to each end face.

Although the linear motion device has been described as being a linear guide device, the same effect can be obtained even if the present invention is applied to a ball screw device as the linear motion device.
In this case, a ball screw shaft as a fixed body of the linear motion device is supported by a ball nut as a moving body through a plurality of metal balls so as to be movable, and an axial track as a rolling element guide surface of the fixed body Circulating both ends of the load path formed by placing the groove and the nut raceway groove as the rolling element guide surface of the moving body in opposition with a resin return tube, end cap, and top as a resin member A metal detection sensor is provided on a resin member that forms a path and a part of the circulation path, and a ball passing time interval is detected by the metal detection sensor, and the revolution speed Vb is calculated before step S1. The step of inputting the specification value of the shape of the ball screw device for the operation is provided, and the operator is informed of the lead L of the shaft raceway groove, the ball pitch circle diameter Dm, the ball diameter Dw, By inputting the specification value of the shape composed of the contact angle α with the nut raceway groove and the shaft raceway groove, in step S2, the moving speed Vs of the slider 6 and the geometrical relationship regarding the rolling shown in the equation (2). Based on the above, the revolution speed Vb of the ball may be calculated.

In this case, the revolution speed Vb is
Vb = πDm (1− (Dw / Dm) cos α) Vs / 2L (2)
It calculates using the geometrical relationship which becomes.
Furthermore, even if the present invention is applied to a roller screw device as a linear motion device in which the rolling element of the ball screw device is a cylindrical roller, the same effect can be obtained.

The perspective view which shows the linear guide apparatus of an Example. The block diagram which shows the abnormality determination apparatus of an Example The flowchart which shows the abnormality determination process of an Example Explanatory drawing which shows the waveform of the sensor output signal of the metal detection sensor of an Example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Linear guide apparatus 2 Rail 3 Rail mounting hole 5 Rail track groove 6 Slider 6a Sleeve wall 7 Mounting screw hole 8 Slider track groove 9 Ball 10 Return path 11 End cap 11a Sleeve part 12 Direction change path 14 Circulation path 16 Metal detection sensor 18 Lead wire 20 Abnormality determination device 21 Control unit 22 Storage unit 23 Clock unit 24 Display unit 25 Input unit 26 Alarm unit 30 Drive device

Claims (2)

In a linear motion device comprising: a stationary body; a movable body supported by the stationary body through a plurality of metal rolling elements; and a circulation path through which the rolling elements circulate.
The resin member constituting a part of the circulation path is provided with a metal detection sensor that detects the approach of the rolling elements circulating in the circulation path,
A linear motion device characterized in that the metal detection sensor detects a passing time interval of the rolling elements. A fixed body, a movable body supported by the fixed body through a plurality of metal rolling elements, a circulation path through which the rolling elements circulate, and a resin member constituting a part of the circulation path An abnormality determination device for a linear motion device, comprising: a metal detection sensor provided to detect the approach of the rolling elements that circulate in the circulation path;
Means for storing an abnormal rolling element interval for calculating an abnormality determination passage period when determining a circulation abnormality of the rolling element circulating in the circulation path;
Means for detecting a passage time interval of the rolling elements from a sensor output signal of the metal detection sensor;
Means for calculating a revolution speed of the rolling element based on a geometric relationship relating to rolling of the rolling element and a moving speed of the moving object;
Means for dividing the abnormal rolling element interval by the calculated revolution speed to calculate the abnormality determination passage period;
An abnormality determination device for a linear motion device, comprising: means for determining that a circulation abnormality has occurred in the circulation path when the detected passage time interval is equal to or greater than the abnormality determination passage period.

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