JP2017181180A - Method and device for managing life of feed shaft of machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately and easily manage the life of a power conveying mechanism forming the feed shaft of a machine according to the actual situation in which the mechanism is used.SOLUTION: The present invention relates to a method for managing the life of a power conveying mechanism 10 forming the feed shaft of a machine, the method including the steps of: dividing the stroke S of the feed shaft into plural regions Sto S; integrating the moving times of the feed shaft or the moving amounts of the feed shaft on a region-by-region basis; and determining whether the integrated moving time or moving amount obtained in the integration step has reached the predetermined region life of the power conveying mechanism.SELECTED DRAWING: Figure 1

Description

  The present invention relates to life management of a machine feed shaft, and more particularly to life management of a power transmission mechanism constituting a machine feed shaft and the like.

  Conventionally, a ball screw is used, for example, in a linear feed shaft of a machine tool. The ball screw includes a rotating screw shaft and a nut that engages with the screw shaft and performs linear motion. A plurality of balls are incorporated inside the nut in order to reduce friction with the screw shaft. Moreover, the slider which attaches a workpiece | work is being fixed to the nut.

The life of the ball screw can be calculated based on data provided by the ball screw manufacturer, and is expressed as the total number of revolutions shown below or as a life time or a life travel distance converted from the total number of revolutions.
Total number of revolutions (rated life) L = (Ca / Fa · fw) ³ × 10 ⁶ (rev)
Life time Lh = L / 60 ・ N = L ・ Ph / 2 ・ 60 ・ n ・ S (H)
Life moving distance Ls = L · Ph / 10 ⁶ (km)
here,
Ca: Basic dynamic load rating (N)
Fa: Axial load (N)
fw: load coefficient n: number of reciprocations per minute (min ⁻¹ )
Ph: Ball screw lead (mm)
S: Stroke (mm)
It is.
Therefore, the user of the machine tool can manage the life of the ball screw by storing, for example, the rotation time of the screw shaft of the ball screw of the machine tool as data and comparing it with the life time.

  Patent Document 1 describes a method for determining a period until an essential maintenance of a machine element is reached. In this method, the force (load) acting at each position of the stroke generated by the feed shaft is measured and integrated. Then, the remaining life is obtained by comparing the integrated force with a preset limit amount.

Special table 2009-518705 gazette

  An actual ball screw often reaches the end of its life before reaching its calculated total speed, life time, or life travel distance. This is a value assuming that the total number of rotations of the ball screw is used evenly, whereas the total number of rotations is frequently used for machining on the screw shaft of an actual machine tool. This is because an area and a low area are generated, and wear of the screw shaft in the high-frequency area precedes. If the backlash increases at a portion where the wear of the screw shaft has progressed and a predetermined processing accuracy cannot be obtained, the ball screw reaches the end of its life. Conventionally, such unexpected arrival of the life of the ball screw may have a great influence on the production plan or the equipment plan.

  In Patent Document 1, the integrated value of the force acting on the ball screw is compared with a predetermined limit amount, and the life is determined. However, the limit value of such integrated value of force is highly reliable in relation to the life. Predetermining as data is not easy. Such data is not generally known.

  The present invention has been made in view of the above circumstances, and it is an object of the present invention to accurately and easily manage the life of a power transmission mechanism constituting a feed shaft of a machine in accordance with the actual usage.

  In order to achieve the above object, according to the present invention, there is provided a life management method for a feed shaft of a machine constituted by a power transmission mechanism, the step of dividing the stroke of the feed shaft into a plurality of regions, Step of integrating the movement time or the amount of movement of the feed shaft for each area, and determining whether the accumulated movement time or accumulated movement amount accumulated in the step of accumulating has reached the predetermined area life of the power transmission mechanism There is provided a method for managing the life of a feed axis of a machine including the steps of:

  In order to achieve the above-described object, according to the present invention, there is provided a life management device for managing the life of a feed shaft of a machine constituted by a power transmission mechanism, which divides the stroke of the feed shaft into a plurality of regions, A counter unit that accumulates the movement time of the feed axis or the movement amount of the feed axis for each area, and determines whether the accumulated movement time or the accumulated movement amount has reached a predetermined area life of the power transmission mechanism There is provided a life management device for a feed axis of a machine, comprising: a wear determination unit that performs the operation and a notification unit that displays an accumulated movement time or an accumulated movement amount for each area together with the area life.

  According to the present invention, the stroke of the feed axis is divided, and the movement amount and the movement time of the feed axis are integrated and monitored for each divided area, so that the life can be managed accurately. In addition, if the consumption level is notified for each area, it is possible to level the consumption level by actively using areas where consumption has not progressed.

It is a figure which shows typically an example of the power transmission mechanism with which the lifetime management method by embodiment of this invention is applied. It is a figure which shows typically another example of the power transmission mechanism with which the lifetime management method by embodiment of this invention is applied. It is a block diagram of the lifetime management apparatus by embodiment of this invention.

Hereinafter, a life management method for a power transmission mechanism according to an embodiment of the present invention will be described with reference to the drawings.
A power transmission mechanism 10 to which the life management method according to the present embodiment is applied is shown in FIG. The power transmission mechanism 10 of FIG. 1 is used for a linear feed shaft of a machine tool such as a machining center, in this example, a Y-axis feed shaft in which a slider 13 as a table on which a workpiece W is placed moves reciprocally linearly. This is a ball screw 10. The ball screw 10 includes a screw shaft 11 as a first machine element and a nut 12 as a second machine element screwed to the screw shaft 11. A plurality of balls (not shown) are incorporated in the nut 12 in order to reduce the friction of the screwing portion. The nut 12 is coupled to the slider 13, and the screw shaft 11 is coupled to an electric motor (not shown) that rotationally drives the nut. The screw shaft 11 is rotatably supported by two bearing portions 14 of the machine tool. The slider 13 is slidably supported by a guide rail 15 of the machine tool.

  Since the power transmission mechanism 10 is configured as described above, when the screw shaft 11 rotates forward and backward by the electric motor, the nut 12 and thus the slider 13 reciprocate linearly. The stroke S of the linear movement of the nut 12 is set to be shorter than the length between the two bearing portions 14 by at least the thickness of the nut 12. In this specification, the stroke S of the nut 12 is also referred to as the stroke S of the feed shaft or simply the stroke S.

In the life management method of the present embodiment, the stroke S is equally divided into a plurality of areas, for example, four areas S _{1 to} S ₄ as shown in FIG. 1, and the degree of wear for each of the divided areas S _{1 to} S _4. Is monitored. In that case, the life time or the life travel distance of the ball screw is also divided into ¼. In this specification, the life time and the life movement distance divided according to the division of the stroke S are referred to as the area life time and the area life movement distance, respectively, and are collectively referred to as the area life. In the example of FIG. 1, for example, if the life time is 20000 hours, the area life time is 5000 hours, and if the life movement distance is 20000 km, the area life movement distance is 5000 km.

Here, first, a case where the area lifetime is monitored will be described as an example. The method of the present embodiment, when the machining program is a command to move the Y-axis, integrated for each region S ₁ to S ₄ to calculate the travel time for each of the regions S ₁ to S _4, 4 one region S ₁ to S cumulative travel time is accumulated for each of ₄ determines whether or not reached in a predetermined area lifetime of the power transmission mechanism 10.

More specifically, in this method, the travel time is calculated from the machining program, so when the machining program is executed, the machine control device sets the program start time and calls the travel time data input program. In the travel time data input program, the travel time is calculated for each block of the machining program. The movement time is calculated if the machining program commands the Y-axis movement. Then, it is checked whether or not each of the areas S _{1 to} S ₄ is included in the movement range. For the areas S _{1 to} S ₄ included in the movement range, the movement time is calculated, and the calculated value is calculated. but cumulative travel time is updated is added to a separate machining program including by integrating moving time accumulated in each region S ₁ to S ₄ that time. Therefore, according to this method, with respect to a certain machine tool, the movement time is calculated for each of the regions S _{1 to} S ₄ in all the machining programs that command it, and the calculated movement time is calculated for each of the regions S _{1 to} S _4. Is accumulated. Similarly, the accumulated movement time may be calculated and accumulated for the X-axis and Z-axis feed axes of the machine tool.

Immediately after the end of one block of the machining program, the machine control device calls the consumable product operating time count monitoring processing program. In the consumables operating time count monitoring processing program, the accumulated movement time of each of the areas S _{1 to} S ₄ is sent to the display device and displayed together with the area life time, while reaching the area life time (threshold value). It is checked whether or not it exists. If there is even one region where the accumulated movement time has reached the region lifetime, a message notifying that the lifetime has been exceeded is displayed on the display device, and the cycle is stopped.

Next, a case where the area life movement distance is monitored will be described. This method, when the machining program is a command to move the Y-axis, integrated for each region _S 1 to S ₄ to calculate the moving distance for each region _S 1 to S _4, 4 one region _S 1 to S ₄ is determined whether or not the accumulated movement distance accumulated for each of the _four reaches the predetermined area life movement distance of the power transmission mechanism 10.

More specifically, in this method, since the movement distance of the Y axis is calculated from the machining program, when the machining program is executed, the machine control device calls the movement distance data input program. In the movement distance data input program, the movement distance is calculated for each block of the machining program. The calculation of the movement distance is calculated for the regions S _{1 to} S ₄ included in the movement range based on the movement start coordinates and movement end coordinates of the Y axis of the machining program if the Y axis movement is commanded. The calculated value is added to the accumulated moving distance accumulated for each of the regions S _{1 to} S ₄ including other machining programs, and the accumulated moving distance is updated. Therefore, according to this method, with respect to a certain machine tool, the movement distance is calculated for each of the regions S _{1 to} S ₄ by all the machining programs that command it, and the calculated movement distance is calculated for each of the regions S _{1 to} S _4. Is accumulated. Similarly, the accumulated movement distance may be calculated and stored for the X-axis and Z-axis feed axes of the machine tool.

Immediately after the end of one block of the machining program, the machine control device calls a consumable working distance count monitoring processing program. In the consumables working distance count monitoring processing program, the accumulated movement distance of each of the areas S _{1 to} S ₄ is sent to the display device and displayed together with the area life movement distance, while the area life movement distance (threshold) is set. It is checked whether it has been reached. If there is at least one area where the accumulated movement distance has reached the area life movement distance, a message notifying that the life has been exceeded is displayed on the display device and the cycle is stopped.

In the above-described embodiment, the area life time and the area life moving distance are monitored, but the method according to this embodiment can also monitor the total area rotation speed based on the total rotation speed. In this case, when the machining program commands the Y-axis movement, the movement distance is calculated for each of the areas S _{1 to} S ₄ and then converted into the rotation speed, and the rotation speed is converted into the areas S ₁ to S. It accumulates every ₄ and determines whether or not the accumulated rotational speed accumulated for each of the _four areas S _{1 to} S ₄ has reached a predetermined total rotational speed (threshold value) of the power transmission mechanism 10. .

  The life management method of the above-described embodiment is applied to a linear feed shaft of a machine tool. However, the life management method according to the present invention is a rotary feed shaft such as an A axis, a B axis, or a C axis of a machine tool. It is also possible to apply to. The power transmission mechanism 20 constituting the rotary feed shaft is composed of, for example, a worm 21 and a worm wheel 22 as shown in FIG. In this case, the first mechanical element of the power transmission mechanism 20 is the worm 21, and the second mechanical element is the worm wheel 22. Since the worm 21 is connected to an electric motor (not shown) for driving the worm 21, the worm wheel 22 performs reciprocating rotational motion in accordance with forward and reverse rotation of the electric motor. The worm wheel 22 is mounted coaxially with a rotary table (not shown).

The stroke S of the rotary feed shaft is expressed in units of angles as the rotational stroke S of the worm wheel 22. In the present embodiment, the rotation stroke S is set to exactly 360 degrees, which are equally divided into _six areas S _{1 to} S ₆ . The area life time and the area life movement distance of the worm wheel 22 are determined in advance.

When the area life time is monitored, the rotational movement time of the worm wheel 22 is calculated for each of the areas S _{1 to} S ₆ from the machining program, as can be inferred from the embodiment applied to the linear feed shaft described above. S ₁ to S accumulates every ₆ determines whether it has reached into six regions S ₁ to S ₆ each accumulated the cumulative revolution movement time predefined regions lifetime with respect of (threshold).

When monitoring the area life movement distance, the rotation angle of the worm wheel 22 is calculated for each of the areas S _{1 to} S ₆ from the machining program, as can be inferred from the embodiment applied to the linear feed shaft. it was integrated for each region S ₁ to S _6, whether or not integrated has been accumulated rotation angle for each of the six areas S ₁ to S ₆ reaches a predetermined area rotational life angle (threshold) judge.

  The “movement distance” when the method according to the present embodiment is applied to the linear feed shaft and the “rotation angle” when the method is applied to the rotary feed shaft are both the movement amounts produced by the linear feed shaft or the rotary feed shaft. Therefore, in the present specification, they are collectively referred to as “movement amount of the feed shaft” or simply “movement amount”.

  According to the life management method of the present embodiment, the stroke S of the feed shaft is divided, and the movement amount and the movement time of the feed shaft are integrated and monitored for each divided area, so that the life is accurately managed. It becomes possible. Further, in order to level the level of wear, for example, a measure that shifts to a region where wear has not progressed can be applied to a workpiece with little axial movement. Furthermore, when an area that has reached the end of its life has occurred, if it is possible to perform machining while avoiding that area, it is possible to avoid immediately stopping the operation of the machine tool.

Next, a life management apparatus according to an embodiment of the present invention capable of implementing the above-mentioned life management method will be described with reference to FIG. 3 which is a block diagram thereof.
The life management apparatus of this embodiment is formed as one component of the machine control apparatus of a machine tool. FIG. 3 also shows a reading interpretation unit 42, an interpolation calculation unit 43, a servo control unit 44, each feed shaft motor 45 and each input shaft motor 45 related to the life management device, and an input unit 41 which is a component of the machine control device. Has been.

  The life management apparatus 30 according to the present embodiment includes an axis movement monitoring unit 31, a counter unit 32, a wear determination unit 34, a life database 35, an area life block 36, and a display device 37. The following describes how these components work.

  The number of divided areas of the stroke S and the rotation stroke S of each axis of the machine tool is input to the axis movement monitoring unit 31 via the input unit 41. Further, the machining program is transferred to the axis movement monitoring unit 31 via the reading / interpreting unit 42 of the NC device. Then, the axis movement monitoring unit 31 calculates the movement time, the movement amount, and the rotation amount of the first machine element for each area for each block of the machining program, and sends it to the counter unit 32. The counter unit 32 accumulates the three types of data of each axis sent from the axis movement monitoring unit 31 for each axis region, and sends the accumulated data to the wear determination unit 34.

  On the other hand, the life database 35 stores the total rotation speed, life time, and life movement distance (rotation amount, time, distance), which are the rated life of each feed shaft, input via the input unit 41. These life data in the life database 35 are sent to the area life block 36, where the area life of each feed axis is calculated based on the number of areas sent from the axis movement monitoring unit 31. The wear determination unit 34 sends the integrated data sent from the counter unit 32 and the region life for each region of each axis to the display device 37, compares them, and the integrated data becomes the region life (threshold). If there is a region that has reached, a message to that effect can be sent to the display device 37 and a cycle stop signal can be sent to the reading and interpreting unit 42.

  The power transmission mechanism life management method and life management device according to the present invention includes, for example, a feed screw composed of a nut and a screw shaft that does not have a ball if it is a linear feed shaft, and a Ouchi within a rack and pinion and a rotary feed shaft. Power transmission mechanisms such as gears and pinions, large external gears and pinions, and planetary gears can be used for life management.

10 Power transmission mechanism (ball screw)
DESCRIPTION OF SYMBOLS 11 Screw shaft 12 Nut 13 Slider 14 Bearing part 20 Power transmission mechanism 21 Worm 22 Worm wheel S Stroke S1-S4 area | region

Claims (5)

A life management method for a feed shaft of a machine constituted by a power transmission mechanism,
Dividing the stroke of the feed shaft into a plurality of regions;
The step of integrating the movement time of the feed shaft or the amount of movement of the feed shaft for each region, and the accumulated movement time or the accumulated movement amount accumulated in the step of accumulating the predetermined region lifetime of the power transmission mechanism A method for managing the life of a feed axis of a machine, comprising the step of determining whether or not it has been reached.   The life management method for a machine feed shaft according to claim 1, wherein the machine feed shaft is a linear feed shaft or a rotary feed shaft. The power transmission mechanism that constitutes the linear feed shaft includes a first machine element that performs a rotational motion, and a second machine element that engages with the first machine element. A second mechanical element that performs reciprocating linear motion based on rotational motion;
The life management method of the feed axis of the machine according to claim 2, wherein the movement amount of the feed axis is expressed by a movement distance of the second machine element. The power transmission mechanism that constitutes the rotary feed shaft includes a first machine element that performs a rotational motion, and a second machine element that engages with the first machine element, the rotation of the first machine element A second mechanical element that performs a reciprocating rotational motion based on the motion,
The life management method of the feed axis of the machine according to claim 2, wherein the movement amount of the feed axis is expressed by a rotation angle of the second machine element. A life management device for managing the life of a feed shaft of a machine constituted by a power transmission mechanism,
A counter unit that divides the stroke of the feed shaft into a plurality of regions and integrates the travel time of the feed shaft or the travel amount of the feed shaft for each region;
An attrition determination unit for determining whether an accumulated movement time or an accumulated movement amount has reached a predetermined area life of the power transmission mechanism;
Informing means for displaying the accumulated accumulated movement time or accumulated movement amount for each area together with the area life;
A service life management device for a feed axis of a machine.

Images