JP4676384B2 - Linear drive unit with dustproof structure - Google Patents

Description

  The present invention relates to a linear drive device used in a machine tool, a robot, various industrial machines, and the like, and more particularly to a linear drive device that includes at least two linear drive units and that is configured so that the drive directions of the linear drive units intersect.

  In machine tools, robots, and various industrial machines, a linear drive device including a linear drive unit including a guide and a slide that can move in one direction along the guide is known as a movable member. Since this linear drive means the slide moves along the guide, as a method for preventing dust from adhering to the guide which is the sliding surface of this slide and increasing the sliding resistance of the slide, It is known to provide a dustproof cover on the exposed part of the guide for the purpose of dustproofing.

  In particular, in machine tools, the workpiece to be machined is linearly moved in two orthogonal axes, and the workpiece is machined by moving the tool in the direction perpendicular to the workpiece movement direction. In many cases, the moving directions of the linear driving means are orthogonal. Also known is a machine tool provided with an inclined axis in which the moving axis direction intersects at an angle other than 90 degrees instead of the orthogonal linear moving axis. In such a machine tool, when chips generated during processing adhere to a member such as a guide of the linear drive means, the movement of the slide moved along the guide is hindered, and the processing accuracy is deteriorated. There's a problem.

  Similarly, in the work environment in which the robot is installed, the operation accuracy of the robot is lowered due to dust adhering to members such as guides of the linear drive means of the robot. For this reason, it is also known that the guide portion is covered with a bellows structure cover to prevent intrusion of dust (see Patent Document 1).

  In addition to machine tools and robots, in industrial machines that include linear drive means and linearly move movable parts such as slides, guide the slide to prevent dust from entering the linear drive means. A linear drive device having a dustproof cover made of bellows or the like covering an exposed surface of a guide is known.

  This dustproof cover with bellows structure has one end attached to the slide and the other end attached to a fixed part such as a guide end, and is configured to expand and contract as the slide moves to cover the exposed part of the guide Yes.

JP-A-6-39776

  FIG. 4 is a perspective view of a conventional linear drive device including two linear drive means arranged so that the linear drive direction is perpendicular to the horizontal direction and the linear drive direction is orthogonal. The horizontal linear driving means 1 has a guide 11 for guiding the horizontal slide 10 in the horizontal direction. The horizontal slide 10 is guided in the horizontal direction by the guide 11 and linearly moves. Similarly, the vertical linear driving means 2 includes a vertical slide 20 and a guide 21 extending in the vertical direction. The vertical slide 20 is guided by the vertical guide 21 and moves in the vertical direction. Bellows-structured dustproof covers 12 and 22 are attached to one ends of the slides 10 and 20 of the linear drive means 1 and 2, respectively, and the other ends of the dustproof covers 12 and 22 are the other end of the guide 11 or the guide 21 It is attached to a fixing member at the end.

  As the horizontal slide 10 and the vertical slide 20 are linearly moved by being guided by the guides 11 and 21, the bellows structure of the dustproof covers 12 and 22 is expanded and contracted, and the cover of the exposed surfaces of the guides 11 and 21 is held. Intrusion to the surface of 21 and the inside of the linear drive means is prevented.

FIG. 5 is a front view for explaining the expansion / contraction state of the bellows structure of the dust-proof cover 12 in the horizontal linear driving means by the movement of the horizontal slide 10. From the state of FIG. FIG. 5B shows a state in which is driven. In the state of FIG. 5B, the horizontal slide 10 receives a force in the direction opposite to the moving direction from the contracted bellows structure of the dust cover 12.
Similarly, also in the vertical drive means 2, when the vertical slide 20 moves downward and contracts the bellows structure of the dust cover 22, the vertical slide 20 receives an upward force in the direction opposite to the moving direction.

Thus, when the bellows structure of the dust covers 12 and 22 is contracted, the slides 10 and 20 receive a force due to the contraction of the bellows structure, and the drive current of the motor of the driving means for driving the slides 10 and 20 increases. Will do.
FIG. 6 is a graph obtained by experimenting the relationship between the position of the slide 10 (or 20) and the drive current of the motor that drives the slide 10 (or 20).

The linear movement stroke of the slide 10 (or 20) is 150 mm, and in FIG. 6, the right direction is the direction in which the bellows structure of the dustproof cover 12 (or 22) is contracted, and the left direction is the direction in which it is extended.
When the bellows structure is contracted by moving the slide 10 (or 20) (the position of the slide on the horizontal axis is 150 mm), a motor that drives the slide 10 (or 20) by a repulsive force generated along with the contraction of the bellows structure The drive current of is increasing. On the other hand, even when the bellows structure is extended (the slide position on the horizontal axis is 0 mm), the drive current of the motor increases. This is because a force for pulling the slide 10 (or 20) is generated in the bellows structure when the bellows structure is extended.

As described above, the current for driving the slide 10 (or 20) varies depending on the position of the slide 10 (or 20). This means that the optimum gain for controlling the movement of the slide 10 (or 20) is the slide 10 (or 20). Or 20), which is a disadvantageous factor for accurately positioning the slide.
Furthermore, when the bellows structure is fully contracted or fully extended, the slide cannot move any further.

  Further, the relationship between the force acting on the slide 10 (or 20) when the bellows structure is contracted and the force acting on the slide 10 (or 20) when the bellows structure is extended depends on the length of the bellows structure.

  In order to reduce the pulling force acting on the slides 10 and 20 when the bellows structure of the dustproof covers 12 and 22 is extended, the bellows structure of the dustproof covers 12 and 22 may be lengthened. When the bellows structure is contracted, there is a problem that the repulsive force applied to the slides 10 and 20 increases and the drive current of the motor increases.

  This problem is due to the provision of two linear drive means whose driving directions cross each other. If the bellows structure of the dust-proof cover can be made longer than the moving stroke of the slide, and no special force is applied to the slide by the expansion and contraction and extension of the bellows structure, this problem does not occur. For example, in FIG. 5, no dust cover is shown on the left side of the horizontal slide 10 and on the upper end side of the vertical slide 20. However, this part is usually provided with a dust cover. There is no particular obstacle on the driving direction extension line on the left side of the horizontal slide 10 and on the driving direction extension line on the upper end side of the vertical slide 20. A dustproof cover is attached to the slides 10, 20 and the slides 10, 20 move. The dust cover can also be moved to cover the surfaces of the guides 11 and 21 so that the guides 11 and 21 are not exposed to the outside. Further, when the dustproof cover is configured with the bellows structure, the slide can be configured not to receive a particularly large force due to contraction and extension of the bellows structure by lengthening the bellows structure portion.

  However, at the intersection side where the driving directions of the two linear driving means intersect, the end position of the dustproof cover on the side opposite to the side attached to the slide is limited. For example, in FIG. 5, the position of the horizontal linear drive means 1 attached to the guide end of the bellows structure dust cover 12 of the bellows structure is attached to the right side beyond the bellows structure dust cover 22 of the vertical linear drive means 2. It is not possible. Naturally, when a plate-like dustproof cover other than the bellows structure is attached to the horizontal slide 10, the dustproof cover and the dustproof cover 22 of the linear drive means 2 in the vertical direction interfere with each other. It cannot be installed.

  Similarly, in the dustproof cover 22 with the bellows structure of the linear drive means 2 in the vertical direction, it is difficult to attach the dustproof cover 22 with the bellows structure at a lower part farther from the end of the guide 21. Usually, the base or the like for attaching the horizontal linear drive means 1 is disposed below the drive direction of the vertical linear drive means 2, so that the position where the end of the bellows structure is attached is limited and dustproof. The length of the bellows structure of the cover is limited, and it is difficult to reduce the force generated as the bellows structure contracts and expands.

  Accordingly, an object of the present invention is to reduce the force caused by the contraction and extension of the dustproof cover of the bellows structure received by the slide of the linear drive means in a linear drive apparatus that includes at least two linear drive means and whose driving directions intersect. It is to provide a linear drive device.

  The present invention relates to a linear drive device having a structure in which two linear drive means constituted by a guide and a slide that can move in one direction along the guide intersect each other. A bellows-type dustproof cover that covers the guide portion is folded and attached between the slides. This reduces the force that the slide receives due to the expansion and contraction of the bellows structure.

  In addition, the bellows structure dustproof cover has a U-shape, and a stationary member is attached so as to cover the end of the U-shape, so that the labyrinth structure is formed by the dustproof cover and the stationary member. Further, the slide is supported by a hydrostatic air bearing with respect to the guide of the linear drive means. Further, the linear drive is used for the slide drive of the linear drive means.

  On the side where the two linear drive means intersect, a dustproof cover with a common bellows structure is used as a dustproof cover to cover the guide, so that the bellows structure can be lengthened, and the slide of one linear drive means contracts the bellows structure. Even if it moves, the bellows structure is contracted to the portion covering the guide of the other linear drive means, the repulsive force generated by the contraction of the bellows structure is small, and the force received by the slide is small. Similarly, the same applies when the bellows structure is extended. Therefore, position control of the motor that drives the slide becomes easy.

  FIG. 1 is an explanatory diagram of a main part of a linear drive device according to a first embodiment of the present invention. FIG. 1A is a perspective view of the embodiment, and FIG. 1B is a front view thereof. Corresponding members in the conventional linear drive device shown in FIGS. 4 and 5 are given the same reference numerals. And the difference from the conventional linear drive device is that the dustproof cover of the bellows structure on the side where the drive direction line of the horizontal linear drive means and the vertical linear drive means intersect is common. .

  The linear drive device includes a horizontal linear drive unit 1 and a vertical drive unit 2, and the horizontal linear drive unit 1 includes a guide 11 provided on a fixing member (not shown) such as a base, It has a horizontal slide 10 that is disposed above and is moved in the horizontal direction along the guide 11 by a motor (not shown). The vertical linear drive means 2 also includes a guide 21 attached to a fixing member such as a column, and a vertical slide 20 guided on the guide 21 by the guide 21 and driven by a motor (not shown).

  The moving direction center line of the guide 11 to which the horizontal slide 10 of the horizontal linear driving means 1 moves and the moving direction center line of the guide 21 to which the slide 20 of the vertical linear driving means 2 move are orthogonal to each other. The surfaces of the guides 11 and 21 for guiding the slides 10 and 20 of the linear driving means 1 and 2 in the horizontal direction and the vertical direction are orthogonal to the moving direction center line of the other linear driving means.

  And, on the side where the movement direction center line of the guides 11 and 21 guided by the slides 10 and 20 intersects, a common bellows structure for covering the guides 11 and 21 of the two linear driving means 1 and 2 is formed. A dustproof cover 3 is provided. That is, one end of the bellows structure dustproof cover 3 is attached to the horizontal slide 10 of the horizontal linear drive means 1, the bellows structure dustproof cover 3 is bent, and the other end is the vertical slide of the vertical linear drive means 2. 20 is attached. The dust-proof cover 3 having the bellows structure covers the guides 11 and 21, and prevents dust from entering the linear driving means 1 and 2 such as the guides 11 and 21. Note that a dustproof cover is also provided on the other end of the slides 10 and 20, that is, on the left side of the horizontal slide 10 and the upper side of the vertical slide 20 in FIG. 1B. Since the mounting method is not subject to special restrictions, the force received from the dust cover by the movement of the slides 10 and 20 can be small.

  As shown in the direction of arrow A in FIG. 1B, when the horizontal slide 10 is moved in a direction approaching the vertical slide 20, the bellows structure on the vertical slide 20 side is also moved through the bent portion of the bellows structure of the dustproof cover 3. Since it shrinks, the horizontal slide 10 can move in a direction closer to the vertical slide 20, and the reaction force from the dustproof cover 3 having the bellows structure to the slide 10 is also reduced. In addition, when the horizontal slide 10 or the vertical slide 20 is moved in the direction in which the bellows structure of the dust cover 3 is extended, the force applied to the slides 10 and 20 is reduced by the length of the bellows structure compared to the conventional structure. Further, since the bellows structure of the dustproof cover 3 is a lengthened conventional structure, the number of parts is reduced and the cost is more advantageous than the conventional system using two dustproof covers having the bellows structure.

  Further, in FIG. 1, when the horizontal slide 10 moves to the right and the vertical slide 20 moves downward, the bellows structure of the dust cover 3 is contracted from both sides, and each slide 10, 20 is protected from dust. Although the force received from the cover 3 increases, the force received at this time is about the same as that of the conventional example shown in FIGS. The case receiving such a force is a special state in which the horizontal slide 10 moves to the right and the vertical slide 20 moves downward, and such a state is rare. Compared with the conventional example shown in FIGS. 4 and 5, there are very few cases where the force received by the slides 10 and 20 increases.

  FIG. 2 is an explanatory view of the main part of the second embodiment of the present invention. The second embodiment covers the end portion of the bellows structure of the dustproof cover 3, and dust enters the inside from the end portion. A stationary member 31 having a labyrinth structure is provided. The same members as those in the first embodiment are denoted by the same reference numerals.

  FIG. 2A is a perspective view of the main part of the second embodiment, and FIG. 2B shows the bellows structure portion of the dust cover 3 with respect to the moving direction of the horizontal slide 10 (or vertical slide 20). It is sectional drawing when cut | disconnecting to a perpendicular direction.

  The bellows structure of the dust-proof cover 3 has a U-shape. The U-shaped dust-proof cover 3 and the mounting surfaces of the guides 11 and 21 cover the guides 11 and 21 so that dust can enter inside. Is to prevent. Therefore, there is a possibility that dust may enter the inside from the end of the U-shaped dust-proof cover 3 that moves. In order to prevent dust from entering from this part, the end of the bellows structure of the dust-proof cover 3 The stationary member 31 is provided so as to cover the surface. The stationary member 31 has a labyrinth structure in which a gap 32 is formed between the dustproof cover 3 and the rising portion from the end of the bellows structure, and the dust 32 prevents the dust from entering the inside. In the example shown in FIG. 2, in the cross-sectional view of FIG. 2 (b), the gap 32 is formed in a U-shape to form a labyrinth structure that prevents dust from entering the inside. The stationary member 31 has a shape that conforms to the shape of the bellows structure of the dust-proof cover 3 bent 90 degrees.

  FIG. 3 is an explanatory diagram of the third embodiment of the present invention. This third embodiment includes an air bearing structure between the guides 11 and 21 and the slides 10 and 20, and the slides 10 and 20. 1 and FIG. 2 in that the drive source to be driven is a linear motor. The air bearing structure in the first and second embodiments shown in FIG. 1 and FIG. A linear motor is applied.

FIG. 3 is a cross-sectional view of the slide 10 (20) and the guide 11 (21) cut in a direction perpendicular to the slide movement direction.
A minute gap is formed on the surface where the guide 11 (21) and the slide 10 (20) are opposed to each other, and compressed air is supplied from the slide 10 (20) side or the guide 11 (21) side, so that the air bearing surface 4 And the slide 10 (20) is configured to float with respect to the guide 11 (21). Since the slide 10 (20) does not contact the guide 11 (21) and can move, the friction due to the individual contact does not occur, and the friction force when the slide 10 (20) moves disappears, and the slide 10 (20). The positioning accuracy is improved.

  Further, as shown in FIG. 3, the magnet 5 is disposed on one of the opposed surfaces of the slide 10 (20) and the guide 11 (21), and the coil 6 is disposed on the other surface (the guide 11 in FIG. 3). (21 shows an example in which the magnet is arranged on the slide 10 (20) and the coil 6 is arranged), and a linear motor is formed. By this linear motor, the slide 10 (20) is moved along the guide 11 (21).

  The above-described air bearing structure is also provided when the slide 10 (20) is driven by a drive source having a normal rotary motor other than the linear motor and a conversion mechanism that changes the rotary motion to a linear motion such as a ball screw / nut mechanism. It may be.

  In each of the above-described embodiments, an example is shown in the case where the moving directions of the slides of the two linear driving units are orthogonal to each other. However, the linear driving device used for a machine tool or the like having an inclined shaft has two linear driving units. In some cases, the slide movement direction intersects at an angle other than 90 degrees instead of 90 degrees. Even in such a case, a dustproof cover having a bellows structure on the intersection side may be provided in common for the two linear drive means.

  Two linear driving means, that is, two linear driving means in which the center lines in the moving direction of the guides that drive the slides of the two linear driving means intersect and the guide surfaces on which the slides are guided intersect with each other without being twisted. The dust-proof cover on the intersection side of two linear drive means intersecting the center line in the moving direction of the guide that drives the slide of the means and the axes perpendicular to the moving direction center line and parallel to the guide surface of the slide are parallel to each other As described above, the dustproof cover having the common bellows structure as described above may be applied.

  The linear drive device of the present invention includes two or more linear drive means for linearly moving a movable part, etc. in machine tools, robots, and industrial machines, and the linear drive directions of the two linear drive means intersect. It can be applied to the linear drive device.

It is principal part explanatory drawing of the 1st Embodiment of this invention. It is principal part explanatory drawing of the 2nd Embodiment of this invention. It is principal part explanatory drawing of the 3rd Embodiment of this invention. It is a principal part perspective view of the conventional linear drive device provided with two linear drive means. It is operation | movement explanatory drawing of the conventional linear drive device. In the conventional linear drive apparatus, it is a figure showing the electric current change of the motor which drives this slide by the movement of a slide.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Horizontal linear drive means 2 Vertical linear drive means 3 Bellows structure dust-proof cover 4 Air bearing surface 5 Magnet 6 Coil 10 Horizontal slide 11 Horizontal guide 20 Vertical slide 21 Vertical guide 31 Stationary member 32 Gap

Claims (3)

In a linear drive device having a structure in which a guide and two linear drive means composed of a slide that can move in one direction along the guide intersect, the slide between the two linear drive means, A dustproof cover having a bellows structure that covers the guide portion is bent and attached, and a slide is supported by a hydrostatic air bearing with respect to the guide of the linear drive means, so that solid friction does not occur. Straight drive.   The bellows structure dust-proof cover has a U-shape, and a stationary member is attached so as to cover an end of the U-shape, thereby forming a labyrinth structure by the dust-proof cover and the stationary member. A linear drive device comprising the dustproof structure according to claim 1.   The linear drive device provided with the dustproof structure according to any one of claims 1 and 2, wherein a mechanism for driving the slide of the linear drive means is a linear motor.

Images