Movable body drive section protection device of machine tool

Abstract

To provide a movable body drive section protection device of a machine tool that can solve a problem in which a moving cover of a bellows is more likely to be damaged than a telescopic cover by detecting the damage in an initial stage and can make use of a merit that the moving cover is suitable for high speed movement of each shaft.SOLUTION: A movable body drive section protection device includes: a cutting liquid recovery passage 21 and a cutting liquid recovery tank 22 that recover cutting liquid entering the outside of a bellows 15; and a liquid level detection sensor 23 that detects a liquid level of the cutting liquid recovery tank 22. The presence or absence of damage of the bellows 15 is determined on the basis of an indicated value of the liquid level detection sensor 23.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a protective device for a moving body drive unit of a machine tool, which protects the drive unit of a moving body in a machine tool from cutting water and chips. [Background technology]

[0002] In protective devices for the movable body drive parts of machine tools, movable covers are used to protect the movable body drive parts of each axis from cutting water and chips. Known movable covers include those made of covers with a strong structure such as a telescopic cover (a telescopic cover body in which multiple large and small protective covers, each with a top plate and a side plate, are nested and the protective covers can be slid to make the whole extendable and retractable), and those made of a bellows product that is lighter than a telescopic cover (a bellows body in which peaks and valleys are formed alternately) (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-68183 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0004] In machine tools, the recent demand for shorter machining times has led to a demand for faster movement of each axis. Moving covers, which protect the moving body drive units of each axis from cutting fluid and chips, are preferred for low-speed movement due to their high reliability, while bellows-type moving covers are more commonly used these days due to their high reliability. However, bellows-type moving covers can be damaged by repeated movement of the material, as well as by the effects of cutting fluid and chips. Operating a machine with a damaged cover can allow cutting fluid and chips to penetrate critical parts such as the drive units, resulting in malfunctions.

[0005] In machine tools, with an emphasis on cost reduction and machine efficiency, automation and labor-saving operation of machines are on the rise, and in machines that use moving bellows covers, damage to the bellows can go unnoticed and continue to be operated, which can cause serious damage to the machine. For example, with products called armored bellows covers, which have a thin metal cover added to the front side of the bellows, damage to the bellows is difficult to see, so damage can be noticed late.

[0006] Compared to bellows movable covers, highly rigid movable covers such as telescopic covers are less likely to be damaged and are highly reliable, but when damage does occur, the high rigidity of the telescopic cover itself can lead to damage to the surrounding areas, or the telescopic cover itself can be severely damaged, making it time-consuming to restore the machine.

[0007] Damage to a bellows moving cover often begins on a smaller scale than that to a telescopic cover. That is, it starts with a small hole that expands over time and eventually causes the bellows to break apart. Because the bellows have a small mass, damage rarely progresses rapidly, and if damage can be detected in the early stages, it is possible to replace or repair the bellows with minimal damage to the machine itself.

[0008] The object of the present invention is to provide a protection device for a moving body drive unit of a machine tool that solves the problem that a moving bellows cover is more likely to be damaged than a telescopic cover by detecting damage at an early stage, and that takes advantage of the advantage of being suitable for high-speed movement of each axis. [Means for solving the problem]

[0009] In order to achieve the above object, the present invention comprises the following aspects.

[0010] 1) A protective device for a moving body drive unit of a machine tool in which a bellows is used as a moving body cover, the protective device for a moving body drive unit of a machine tool being characterized in that it is equipped with a cutting fluid recovery passage and a cutting fluid recovery tank for recovering cutting fluid that has entered the outside of the bellows, and a liquid level detection sensor for detecting the liquid level in the cutting fluid recovery tank, and the presence or absence of damage to the bellows is determined based on the indication value of the liquid level detection sensor.

[0011] 2) A protective device for a moving body drive unit of a machine tool according to 1) above, further comprising a timer for measuring the time required for the indicated value of the liquid level detection sensor to reach a set value.

[0012] 3) A protective device for a moving body drive unit of a machine tool as described in 2) above, characterized in that a timer measures the time required for the liquid level detection sensor to indicate a set value from a state in which there is no cutting fluid in the cutting fluid recovery tank, and if the required time is shorter than a preset reference time, it is determined that there is damage to the bellows, and if the required time is longer than a preset reference time, it is determined that there is no damage to the bellows.

[0013] 4) A protective device for a moving body drive unit of a machine tool according to 1) above, characterized in that the liquid level detection sensors include a first liquid level detection sensor that detects when an indication value reaches a first set value, and a second liquid level detection sensor that detects when the indication value reaches a second set value that is higher than the first set value, and further includes a timer that measures the time required from when the indication value of the first liquid level detection sensor reaches the first set value to when the indication value of the second liquid level detection sensor reaches the second set value, and that if the required time is shorter than a preset reference time, it is determined that there is damage to the bellows, and if the required time is longer, it is determined that there is no damage to the bellows. [Effects of the Invention]

[0014] According to the above-mentioned 1) moving body drive unit protection device for machine tools, when the indication value of the liquid level detection sensor is relatively large, it is possible to detect initial damage to the bellows by estimating that the bellows have been damaged and cutting fluid has leaked out from the damaged part of the bellows. When the indication value of the liquid level detection sensor is relatively small, it is possible to prevent erroneous detection of initial damage to the bellows by estimating that the indication value of the liquid level detection sensor is increased during normal times.

[0015] According to the above-mentioned 2) moving body drive unit protection device for machine tools, the use of a timer makes it possible to reliably determine whether or not the bellows is damaged, and to reliably prevent erroneous detection of initial damage to the bellows.

[0016] According to the above 3) moving body drive unit protection device for machine tools, it is possible to reliably determine whether or not the bellows is damaged using only one liquid level sensor, and it is possible to reliably prevent erroneous detection of initial damage to the bellows.

[0017] According to the above-mentioned 4) moving body drive unit protection device for machine tools, by using two liquid level sensors, it is possible to reliably determine whether or not the bellows is damaged in a relatively short time, and it is possible to reliably prevent erroneous detection of initial damage to the bellows. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a cross-sectional view showing an embodiment of a machine tool equipped with a movable body drive unit protection device of the present invention. [Figure 2] 2(a) and 2(b) are diagrams illustrating an example of a determination method in the moving body drive unit protection device. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

[0020] FIG. 1 shows an embodiment of a machine tool (1) equipped with a movable body drive unit protection device (7) of the present invention.

[0021] This machine tool (1) is a vertical machining center and includes a bed (2), a table (3) supported on the bed (2) so as to be freely movable back and forth and supporting a workpiece (W), a spindle head (5) mounted via a column (4) erected on the bed (2), a movable body drive unit (6) that moves the table (3), which is a movable body, and a movable body drive unit protection device (7) that protects the movable body drive unit (6).

[0022] The moving body drive unit (6) is provided with left and right linear guides (11) that are provided on the upper surface of the bed (2) and guide the left and right side portions of the table (3), and left and right ball screws (12) that support the left and right side portions of the table (3) and move the table (3) in the forward and backward directions.

[0023] The moving body drive unit protection device (7) includes left and right inclined covers (13) that cover both the left and right sides of the table (3) from above, an internal conveyor (14) provided below the table (3), and a bellows (moving body cover) (15) that covers the internal conveyor (14).

[0024] The cutting fluid and chips inside the machine are guided to the internal conveyor (14) by the left and right inclined covers (13) and bellows (15), and are then discharged outside the machine by the internal conveyor (14). The inclined covers (13) run from one end of the machine tool to the other, preventing the cutting fluid and chips from entering underneath the table (3). One end of the bellows (15) is connected to the table (3), and the other end of the bellows (15) is connected to a fixed part such as the inclined covers (13), so that the cutting fluid and chips do not leak out through the gap between the table (3) and the fixed part.

[0025] Although there is a small gap between the internal conveyor (14) installed under the table (3) and the bellows (15), the labyrinth structure and wipers prevent cutting fluid and chips from leaking outside the bellows (15) and internal conveyor (14).

[0026] When the bellows (15) is undamaged and in a normal state, most of the cutting fluid and chips are guided to the internal conveyor (14). The bellows (15) isolates the linear guide (11), ball screw (12), and other moving body drive parts (6) from the inside of the machine, but if the bellows (15) is damaged, the cutting fluid and chips will penetrate outside the bellows (15) and accumulate on the bed (2) and near the linear guide (11) and ball screw (12).

[0027] The movable body drive unit protection device (7) has a unique configuration: left and right cutting fluid recovery passages (21) provided inside the bed (2) that allow cutting fluid that has entered the outside of the bellows (15) to flow in the direction indicated by the arrows and be discharged outside the bed (2); and left and right cutting fluid recovery tanks (22) provided outside the bed (2) that recover cutting fluid discharged from the left and right cutting fluid recovery passages (21). Each of the left and right cutting fluid recovery tanks (22) is provided with a liquid level detection sensor (23), which can detect when the cutting fluid accumulates in each cutting fluid recovery tank (22) at or above a set level. The time from when the cutting fluid recovery tank (22) is empty until the liquid level detection sensor (23) detects the empty state can be measured by a timer (not shown).

[0028] The linear guide (11), ball screw (12), and other moving body drive parts (6) are located outside the bellows (15), and when the bellows (15) is in a normal state, cutting fluid and chips do not come into contact with these important structures. In this embodiment, the space where the important structures are located outside the bellows (15) is provided with a cutting fluid recovery passage (21) that can recover cutting fluid and a cutting fluid recovery tank (22) dedicated to recovering leaked cutting fluid, and cutting fluid that has seeped outside the bellows (15) can be recovered in the cutting fluid recovery tank (22).

[0029] It is also possible to provide multiple cutting fluid recovery passages (21), which may be connected to multiple individual cutting fluid recovery tanks (22), or the cutting fluid recovery passages (21) may be combined into one and connected to one cutting fluid recovery tank (22).

[0030] The cutting fluid recovery tank (22) is provided with a fluid level detection sensor (23), which transmits a signal to detect that the fluid level in the cutting fluid recovery tank (22) has reached a set value. Since the damage to the bellows (15) often progresses slowly, even when the damage is minor and there is little damage to important structures, cutting fluid accumulates in the cutting fluid recovery tank (22), making it possible to detect that the bellows (15) have been damaged.

[0031] Various types of commercially available liquid level sensors can be used as the liquid level sensor 23, as long as they can detect only when the cutting fluid recovery tank 22 reaches a set value (for example, full). Of course, the liquid level sensor 23 may also be one that outputs the amount of cutting fluid as a continuous value.

[0032] Because there is a gap between the moving part of the bellows (15) and the fixed part of the inclined cover (13) or the like, even when the bellows (15) is in a normal state, a small amount of cutting fluid may seep through the gap to the outside of the bellows (15). Since the cutting fluid that seeps outside the bellows (15) accumulates in the cutting fluid recovery tank (22), even a small amount of intrusion may eventually be detected, resulting in a false detection of damage to the bellows (15).

[0033] As a first method for avoiding this false detection, the time required for the indication value of the fluid level detection sensor (23) (fluid level height in the cutting fluid recovery tank (22)) to reach a set value is measured by a timer, using the time when no cutting fluid is left in the cutting fluid recovery tank (22) as a trigger O. Regarding this required time, for example, the minimum time when there is no damage is set as a reference time.

[0034] When determining whether or not the bellows (15) is damaged, as shown in Figure 2(a), the reference time S indicated by the two-dot chain line is used as the judgment standard, and if the liquid level in the cutting fluid recovery tank (22) reaches the set value of the liquid level detection sensor (23) at time A (indicated by the solid line) shorter than the reference time S, it is determined that there is damage, and if the liquid level in the cutting fluid recovery tank (22) reaches the set value of the liquid level detection sensor (23) at time B (indicated by the dashed line) longer than the reference time S, it is determined that there is no damage.

[0035] In this way, if it takes more than the reference time for the set value of the liquid level detection sensor (23) to be reached, it is determined that the drain recovery time is normal (no damage to the bellows (15)), and if it is detected within the reference time, it is determined that damage has been detected (damage to the bellows (15)), thereby reliably preventing erroneous detection and making it possible to determine whether or not the bellows are damaged.

[0036] As a second method for avoiding false detection, although not shown, a first liquid level detection sensor that detects when the indication value reaches a first set value and a second liquid level detection sensor that detects when the indication value reaches a second set value that is higher than the first set value are used as the liquid level detection sensor (23).

[0037] When determining whether the bellows (15) is damaged or not, as shown in Fig. 2(b), first, it is determined that there is no damage until the set value of the first liquid level detection sensor is reached, and the time when the set value of the first liquid level detection sensor is reached is set as trigger T, and the time required for the indicated value of the second liquid level detection sensor (liquid level height in the cutting fluid recovery tank (22)) to reach the second set value is measured by a timer. Regarding this required time, for example, the minimum time when there is no damage is set as the reference time.

[0038] Then, using the reference time S shown by the dotted line as the judgment standard, if the liquid level in the cutting fluid recovery tank (22) reaches the set value of the second liquid level detection sensor at time A (shown by the solid line) shorter than the reference time S, it is judged that there is damage, and if the liquid level in the cutting fluid recovery tank (22) reaches the set value of the second liquid level detection sensor at time B (shown by the dashed line) longer than the reference time S, it is judged that there is no damage.

[0039] In this way, if the time required from the time when the indication value of the first liquid level detection sensor reaches the first set value to the time when the indication value of the second liquid level detection sensor reaches the second set value is equal to or longer than the reference time, it is determined that this is a normal drain recovery time (no damage to the bellows (15)), and if the detection is made within the reference time, it is determined that damage has been detected (damage to the bellows (15)), thereby reliably preventing false detections and making it possible to determine whether or not the bellows are damaged.

[0040] According to the second method, it can be determined that the bellows (15) is not damaged until the set value of the first liquid level detection sensor is reached. Therefore, it is only necessary to check whether the bellows (15) is damaged thereafter until the set value of the second liquid level detection sensor is reached, thereby reducing the time required for the check. [Explanation of symbols]

[0041] (1):Machine tools (6): Moving body drive unit (7): Protective device for driving the moving body (11): Linear guide (12): Ball screw (13): Sloping cover (14): In-machine conveyor (15): Bellows (mobile body cover) (21): Cutting fluid collection passage (22): Cutting fluid recovery tank (23): Liquid level detection sensor

Claims

1. A protective device for a moving body drive unit of a machine tool in which a bellows is used as a moving body cover, the device comprising: a cutting fluid recovery passage and a cutting fluid recovery tank for recovering cutting fluid that has entered the outside of the bellows; and a liquid level detection sensor for detecting the liquid level in the cutting fluid recovery tank, and the presence or absence of damage to the bellows is determined based on the indication of the liquid level detection sensor.

2. 2. The device for protecting a movable body drive unit of a machine tool according to claim 1, further comprising a timer for measuring the time required for the indicated value of the liquid level detection sensor to reach a set value.

3. A protective device for a moving body drive unit of a machine tool as described in claim 2, characterized in that a timer measures the time required for the liquid level detection sensor to indicate a set value from a state in which there is no cutting fluid in the cutting fluid recovery tank, and if the required time is short compared to a predetermined reference time, it is determined that there is damage to the bellows, and if the required time is long, it is determined that there is no damage to the bellows.

4. 2. A protective device for a movable body drive unit of a machine tool as set forth in claim 1, characterized in that the liquid level detection sensors include a first liquid level detection sensor that detects when an indication value reaches a first set value, and a second liquid level detection sensor that detects when the indication value reaches a second set value higher than the first set value, and further includes a timer that measures the time required from the time when the indication value of the first liquid level detection sensor reaches the first set value to the time when the indication value of the second liquid level detection sensor reaches the second set value, and if the required time is shorter than a predetermined reference time, it is determined that there is damage to the bellows, and if the required time is longer, it is determined that there is no damage to the bellows.

Images