Lubricant detection method for linear motion systems

Abstract

A lubricant detection method used in a linear motion system (10) comprising a linear module (12), a lubricator (14), a sensor (16), and a processor (18), wherein the linear module (12) comprises a first movable element (121) and a second movable element (122), wherein the first movable element (121) is held in contact with the second movable element (122) such that the first movable element (121) and the second movable element (122) are movable relative to each other, wherein the lubricator (14) is adapted to supply lubricating oil into the first movable element (121), wherein the sensor (16) is attached to the first movable element (121) of the linear module (12) and is held in contact with the first movable element (121), wherein the processor (18) is electrically connected to the lubricator (14) and the sensor (16). connected to receive data from,wherein the lubricant detection method comprises the steps of: Step I: supplying lubricant information to the processor (18) when the lubricator (14) starts to lubricate the first movable member (121), and continuously detecting the lubricant information when the processor (18) does not receive lubricant information; Step II: Allowing the processor (18) to periodically acquire the temperature information measured by the sensor (16) within a certain period of time (T) after the processor (18) acquires the lubricant information, and then allowing the processor (18) to record the acquired temperature information and further generate a temperature curve (L) within the certain period of time (T), and then determining whether there is a dent in the temperature curve (L), and then allowing the processor (18) to generate "error" information indicating a lubrication error if there is a negative determination result; and Step III: Detecting a first starting point temperature value at the time of starting lubrication from the temperature information to form a value A when the indentation exists in the temperature curve (L), and then calculating the average value of the temperature values ​​within 1 / 3 of the time period before the lowest point of the temperature curve (L) to form a value B, and then calculating the average value of the temperature values ​​after 2 / 3 of the time period behind the lowest point of the temperature curve (L) to form a value C; Determine whether the value B is smaller than the value C, and then generate the information "Error" if the determination result is negative, or generate information "Normal" indicating normal lubrication if the determination result is positive.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention

[0001] The present invention relates to lubrication technology of linear motion systems and, more particularly, to a lubricant detection method for use in a linear motion system. 2. Description of the state of the art

[0002] The operation of a linear module such as a screw conveyor is achieved by: rotating a screw shaft to alternately rotate the screw grooves forward or backward, or rotating the screw grooves to alternately rotate the screw shaft forward or backward, to further achieve the effect of driving an object. During the operation of the screw shaft, the balls continuously come into friction with the screw shaft or ball nut. The friction between the balls and the screw shaft or ball nut causes the balls, screw shaft, and ball nut to wear and further generate heat, resulting in an increased temperature on the linear module. If lubricating oil is not provided in a timely manner at this time, abrasion will increase. Typically, a lubricator is operated to provide an appropriate amount of lubricant to reduce the above-mentioned friction.Although the lubricator is turned on to start the lubrication operation, a lubrication error may occur due to a lubricator shutdown, a line leak, or other reasons.

[0003] The existing lubricant detection method for determining whether or not lubricating oil enters the linear module is achieved by installing a flow meter at the end of the lubricant line. The flow meter monitors the supply of lubricating oil to the linear module. The supply of lubricating oil via the lubricator, the pressure of the lubricating oil in the lubricant line, and the presence of the connector between the lubricant line and the flow meter greatly increase the risk of lubricant leakage. Furthermore, at a high movement speed of the linear module, it is not practical to install a flow meter in the linear module. DE 10 2014 101 686 B3 discloses a linear actuator lubrication timing evaluation method consisting of a signal detection step, where a sensor detects physical signals from the linear actuator, a signal conversion step,in which each physical signal is converted into a characteristic value using an algorithm; a characteristic value curve recording step in which a characteristic value curve is recorded with the characteristic values ​​relative to the vertical axis and the time points relative to the horizontal axis in a coordinate system, wherein the horizontal axis in the coordinate system is divided into several time periods; a characteristic value calculation step in which a gradient value is calculated based on each characteristic value complementary to the adjacent time points, thus determining a total based on all gradient values ​​in each time period; and a lubrication evaluation step in which the total sum of the gradient values ​​in each time period is queried for falling below the target value, wherein falling below indicates insufficient lubrication. DE 10 2014 110 612 B3 discloses a method for detecting a bias residual rate, comprising the steps of installing a temperature sensor;Moving the two preloaded elements relative to each other and recording a temperature change over time to obtain an initial temperature rise curve; moving the two preloaded elements relative to each other and recording a temperature change over time to obtain a detected temperature rise curve; and comparing the initial and detected temperature rise curves to obtain the preload residual rate. US Pat. No. 8,253,575 B2 discloses a device for detecting the temperature of a rolling bearing or a part of a housing and a spindle, which part is affected by a temperature change of the rolling bearing, and an abnormality detection section for detecting the abnormality of the rolling bearing by a rate of change of the temperature of the rolling bearing. SUMMARY OF THE INVENTION

[0004] The present invention was made under the given conditions. A primary object of the present invention is to provide a lubricant detection method for use in a linear motion system that eliminates the need for a flow meter, reduces the risk of lubricating oil leakage, and effectively detects the lubrication operation when the movement speed of the linear module is increased.

[0005] To achieve these and other objects of the present invention, the lubricant detection method is employed in a linear motion system comprising a linear module, a lubricator, a sensor, and a processor. The linear module comprises a first movable member and a second movable member. The first movable member is held in contact with the second movable member such that the first movable member and the second movable member are movable relative to each other. The lubricator is adapted to supply lubricating oil into the first movable member. The sensor is attached to the first movable member of the linear module and is held in contact with the first movable member.

[0006] The processor is electrically coupled to the lubricator and the sensor to receive data therefrom. The lubricant detection method includes the steps of (1): providing lubricant information to the processor when the lubricator begins to lubricate the first movable member, and continuously detecting the lubricant information when the processor is not receiving lubricant information;(2): Allowing the processor to periodically acquire the temperature information acquired by the sensor within a certain period of time after the processor acquires the lubricant information, and then allowing the processor to record the acquired temperature information and further generate a temperature curve in the certain period of time, and then determining whether or not there is a dip in the temperature curve, and then allowing the processor to output “error” information indicating that there is a lubrication error in the case of a negative determination;and (3): Detecting a starting point for the temperature value to start lubrication from the temperature information to form a value A when the indentation exists in the temperature curve, and then calculating an average value of the temperature values ​​in 1 / 3 of the time period before the lowest point of the temperature curve to form a value B, and then calculating the average value of the temperature values ​​after 2 / 3 of the time period after the lowest point of the temperature curve to form the value C, and then determining whether the value B is smaller than the value C and then generating the information "error" when the determination result is negative, or generating the information "normal" when the determination result is positive, which indicates a normal lubrication state.;

[0007] Therefore, the lubricant detection method of the present invention eliminates the need for a flow meter, and the risk of lubricating oil leakage is reduced. Furthermore, the dimensions of the sensor are smaller than a flow meter, so detection of the lubrication operation can be achieved when the movement speed of the linear module is increased.

[0008] In addition, the lubricant information can be a high voltage signal, a low voltage signal or a pulse signal.

[0009] The specific time period is preferably selected from 3 seconds to 60 seconds.

[0010] The sensor is preferably attached to the movable element of the linear module. Alternatively, the first movable element can be configured to have a fitting for a lubricant or grease nipple. In this case, the sensor is arranged in contact with the lubricant fitting / grease nipple.

[0011] The linear motion system preferably further comprises an indicator device electrically connected to the processor and adapted to receive the "error" information and the "normal" information. The indicator device is driven by the processor after the processor receives the "error" information or the "normal" information. Furthermore, the indicator device can be a display, a lamp, or a buzzer.

[0012] Other advantages and features of the present invention will be fully understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals designate like structural components. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a schematic drawing showing the structure of a conventional linear motion system. Fig. 2 is a flow block diagram of a lubricant detection method according to the present invention. Fig. Figure 3 is a time-temperature curve obtained according to the present invention. Fig. Figure 4 is a schematic drawing showing value A, value B and value C. DETAILED DESCRIPTION OF THE INVENTION

[0013] According to the Fig. 1-3, the invention provides a lubricant detection method for use in a linear motion system 10 comprising a linear module 12, a lubricator 14, a sensor 16, and a processor 18.

[0014] The linear module 12 in this embodiment is a worm screw. However, the worm screw is not a limitation. Alternatively, the linear module 12 may be a linear guide. The linear module 12 includes a first movable member 121, such as a ball nut or a slide block, and a second movable member 122, such as a worm shaft or slide rail. The first movable member 121 is held in contact with the second movable member 122 such that the first movable member 121 and the second movable member 122 are movable relative to each other.

[0015] The lubricator 14 is adapted to supply a lubricating oil into the first movable member 121.

[0016] The sensor 16 is attached to the first movable element 121 of the linear module 12 and is held in contact with the first movable element 121. In the preferred embodiment, the sensor 16 is a temperature sensor, for example, a thermocouple.

[0017] The processor 18 may be a numerical controller or computer that is electrically connected to the lubricator 14 and the sensor 16 to obtain data.

[0018] The lubricant detection method is used in the linear motion system 10, which includes steps I - III.

[0019] Step 1: When the lubricator 14 begins lubricating the first movable member 121, lubricant information is sent to the processor 18. If the processor 18 does not receive lubricant information, it will continue searching for lubricant information. Note that the lubricant information may be a high-voltage signal, a low-voltage signal, or a pulse signal.

[0020] Furthermore, in the present preferred embodiment, the first movable member 121 is equipped with a lubricator fitting / grease nipple 123. The sensor 16 is in contact with the grease nipple 123. It should be noted that the invention uses the technique of determining the temperature of a specific measurement point and determining the normal state of lubrication operation depending on temperature changes. The lubricating oil in the lubricator 14 is at room temperature. When frictional heat is generated between the first movable member 121 and the grease nipple 123, the temperature of the linear module 12 rises and exceeds the temperature of the lubricating oil.If the temperature difference measured between the lubricating oil and the linear module 12 at the time the lubricating oil enters the linear module 12 is greater than the detected temperature difference between the lubricating oil and the linear module 12 after the lubricating oil enters the linear module 12, the temperature measurement point is preferably at the point where contact between the lubricating oil and the linear module 12 begins. In the currently preferred embodiment, the sensor 16 is held in contact with the grease nipple 123. Alternatively, the sensor 16 may be arranged on the first movable member 121 adjacent to the grease nipple 123.

[0021] Step II: referring again to Fig.3, after the processor 18 acquires the lubricant information, the processor 18 periodically acquires the temperature information acquired by the sensor 16 within a predetermined time period T. In the present preferred embodiment, the processor 18 acquires the temperature information once every second. The predetermined time period T is 50 seconds. Within this predetermined time period T (50 seconds), the processor 18 records the acquired temperature information to generate a temperature curve L, and then determines whether a dip exists in the temperature curve L. If the determination is negative (the dip or slope of the temperature curve L is absent), the processor 18 generates "error" information indicating a lubrication error.It should be noted that in practical application, the specified time period T corresponds to the line length of the lubricator 14, so the specified time period T is selected from the range of 3 seconds to 60 seconds. In practical application, the effect based on a specified time period T shorter than 3 seconds or longer than 60 seconds will be worse than that selected from the range of 3 seconds to 60 seconds.

[0022] Step III: In case of a positive result (the indentation in the temperature curve L exists), a starting point temperature value is acquired from the temperature information to form a value A, then the average values ​​of the temperature values ​​within 1 / 3 of the time period before the lowest point of the temperature curve L are calculated to form a value B, and then the average values ​​of the temperature values ​​after 2 / 3 of the time period behind the lowest point of the temperature curve are calculated to form the value C.

[0023] It is determined whether the value B is smaller than the value C, whereupon the information "Error" is generated if the determination result is negative, and information "Normal" is generated if the determination result is positive, which indicates a normal lubrication condition.

[0024] It should be noted that the linear motion system 10 further includes an indicator 20 electrically connected to the processor 18 and adapted to receive the "error" information and the "normal" information. Upon receipt of the "error" information or the "normal" information, the indicator 20 continues to operate. Furthermore, the indicator 20 may be a display, a lamp, or a buzzer.

[0025] In summary, the invention provides a lubricant detection method for use in a linear motion system that eliminates the need for a flow meter and reduces the risk of lubricating oil leakage. Furthermore, since the sensor's dimensions are smaller than those of a flow meter, detection of lubrication operation can be achieved when the movement speed of the linear module is increased.

Claims

[1] A lubricant detection method used in a linear motion system (10) comprising a linear module (12), a lubricator (14), a sensor (16), and a processor (18), wherein the linear module (12) comprises a first movable element (121) and a second movable element (122), wherein the first movable element (121) is held in contact with the second movable element (122) such that the first movable element (121) and the second movable element (122) are movable relative to each other, wherein the lubricator (14) is adapted to supply a lubricating oil into the first movable element (121), wherein the sensor (16) is attached to the first movable element (121) of the linear module (12) and is held in contact with the first movable element (121), wherein the processor (18) is connected to the lubricator (14) and the sensor (16) is electrically connected to receive data from,wherein the lubricant detection method comprises the steps of: Step I: supplying lubricant information to the processor (18) when the lubricator (14) starts to lubricate the first movable member (121), and continuously detecting the lubricant information when the processor (18) does not receive lubricant information; Step II: Allowing the processor (18) to periodically acquire the temperature information measured by the sensor (16) within a certain period of time (T) after the processor (18) acquires the lubricant information, and then allowing the processor (18) to record the acquired temperature information and further generate a temperature curve (L) within the certain period of time (T), and then determining whether there is a dent in the temperature curve (L), and then allowing the processor (18) to generate "error" information indicating a lubrication error if there is a negative determination result; and Step III: Detecting a first starting point temperature value at the time of starting lubrication from the temperature information to form a value A when the indentation exists in the temperature curve (L), and then calculating the average value of the temperature values ​​within 1 / 3 of the time period before the lowest point of the temperature curve (L) to form a value B, and then calculating the average value of the temperature values ​​after 2 / 3 of the time period behind the lowest point of the temperature curve (L) to form a value C; Determine whether the value B is smaller than the value C, and then generate the information "Error" if the determination result is negative, or generate information "Normal" indicating normal lubrication if the determination result is positive. [2] The lubricant detecting method according to claim 1, wherein the lubricant information is a high voltage signal, a low voltage signal or a pulse signal. [3] The lubricant detection method according to claim 1, wherein the sensor (16) is attached to the first movable member (121) of the linear module (12). [4] The lubricant detection method according to claim 1, wherein the first movable member (121) comprises a grease nipple (123); wherein the sensor (16) is arranged in contact with the grease nipple (123). [5] The lubricant detecting method according to claim 1, wherein the certain time period (T) is selected from the range of 3 seconds to 60 seconds. [6] The lubricant detection method according to claim 1, wherein the linear motion system (10) further comprises a display device (20) electrically connected to the processor (18) and adapted to receive the "error" information and the "normal" information, wherein the display device (20) is driven by the processor (18) after the processor (18) has received the "error" information or the "normal" information. [7] A lubricant detecting method according to claim 6, wherein the indicating means (20) is independently a display, a lamp or a buzzer.

Images