Linear guide mechanism and linear actuator

Abstract

To provide a linear guide mechanism in which the straightness of a guide member lowered by heat-treating the guide member, on which a rolling surface for balls is formed, can be improved without cutting work so that there is no play when a moving block slides and slide resistance is suppressed as much as possible, and to provide a linear actuator mounted with the linear guide mechanism.SOLUTION: A linear guide mechanism includes an actuator side guide member 30, moving block side guide members 24 disposed on both sides of the actuator side guide member, and a plurality of balls 36 disposed in two rows between the actuator side guide member and each of the moving block side guide members, respectively. A moving block is provided with set screws 26 that can adjust a pre-load on the balls and can improve the straightness of the moving block side guide members.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a linear guide mechanism that slidably supports a moving block, such as a slide table having a workpiece mounting surface, on an actuator, and a linear actuator equipped with the same. [Background technology]

[0002] Conventionally, there has been known a linear guide mechanism in which a slide table driven by an actuator is slidably supported on the actuator. In such a linear guide mechanism, it is important to eliminate backlash of the slide table and further reduce the sliding resistance, and it is also known to support the slide table on the actuator using a plurality of rolling elements such as balls.

[0003] For example, Patent Document 1 describes a linear guide device in which a moving block is attached to a track rail via a number of rolling elements. This track rail is composed of a pair of rail members on which the rolling elements are formed, and a rail housing provided with a pair of rail mounting grooves into which the rail members fit, and one of the rail mounting grooves is formed with a reference protrusion that contacts the rail members. The rail member that fits into the other rail mounting groove is fixed using this reference protrusion as a reference, thereby ensuring the parallelism of the pair of rail members. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4531053 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, guide members (rail members) on which the rolling surfaces of the rolling elements are formed often require high hardness, particularly on the rolling surfaces, and the molded products may be subjected to heat treatment (quenching / tempering). In this case, distortion occurs due to the heat treatment, and straightness decreases, so in order to improve this, grinding must be performed after the heat treatment.

[0006] The present invention has been made in consideration of the above circumstances, and has an object to provide a linear guide mechanism and a linear actuator equipped with the same, which can improve the straightness reduced by heat treatment of the guide member on which the rolling surface of the balls is formed, without using grinding, and which eliminates rattling when the moving block slides and minimizes sliding resistance. [Means for solving the problem]

[0007] The linear guide mechanism according to the present invention is for supporting a moving block on an actuator so that the moving block can slide freely, and includes an actuator-side guide member attached to the actuator, a pair of moving block-side guide members attached to the moving block and disposed on both sides of the actuator-side guide member, and a plurality of balls provided in two rows between the actuator-side guide member and each of the moving block-side guide members. The actuator-side guide member includes a circulation member through which the balls circulate. hole The guide member on the moving block side is made of heat-treated steel, and the moving block is provided with a pressing mechanism that can adjust the preload of the balls and improve the straightness of the guide member on the moving block side. The pressing mechanism uses a set screw.

[0008] According to the linear guide mechanism, the straightness of the moving block guide member made of heat-treated steel can be improved by the set screw, so there is no need to perform cutting on the moving block guide member. Also, since the moving block is supported by the actuator by a support structure called a circular arc, in which a plurality of balls are arranged in two rows between the actuator guide member and each moving block guide member, the increase in the sliding resistance of the moving block can be suppressed as much as possible even if the preload of the balls increases when improving the straightness. Effect of the Invention

[0009] The linear guide mechanism of the present invention has a plurality of balls arranged in two rows between the actuator side guide member and the moving block side guide members arranged on both sides of the actuator side guide member, and the moving block is provided with a set screw that can adjust the preload of the balls and improve the straightness of the moving block side guide member.Therefore, the straightness of the moving block side guide member that is reduced by heat treatment can be improved by the set screw, and even if the ball preload increases when improving the straightness, an increase in the sliding resistance of the moving block can be suppressed as much as possible. [Brief description of the drawings]

[0010] [Figure 1] 1 is an external view of a linear actuator according to an embodiment of the present invention; [Diagram 2] FIG. 2 is an external view of a linear guide mechanism mounted on the linear actuator of FIG. 1. [Diagram 3] 3 is a cross-sectional view of the linear actuator of FIG. 1 taken along line III-III. [Figure 4] 2 is a diagram showing the linear actuator of FIG. 1 exploded into parts or parts group viewed from a predetermined direction. [Diagram 5] 1. FIG. 5 is a diagram showing the linear actuator of FIG. 1 exploded into parts or parts groups, as viewed from a different direction than FIG. 4. [Figure 6]2 is a diagram showing a state in which a table-side guide member of the linear actuator in FIG. 1 is curved in the left-right direction. [Figure 7] 2 is a diagram showing a state in which a table-side guide member of the linear actuator in FIG. 1 is curved in the up-down direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] A linear guide mechanism and a linear actuator equipped with the same according to the present invention will be described with reference to preferred embodiments with reference to the accompanying drawings. In the following description, when words related to the directions of up, down, left, and right are used, they refer to the directions in FIG.

[0012] 1 and 2, the linear actuator 10 of this embodiment includes an air cylinder 38 as an actuator, and is equipped with a linear guide mechanism that slidably supports a slide table 12 as a moving block on the air cylinder 38. The linear guide mechanism is made up of the slide table 12, a table side guide member 24 (moving block side guide member), an air cylinder side guide member 30 (actuator side guide member), and a plurality of balls 36 provided between the table side guide member 24 and the air cylinder side guide member 30.

[0013] The slide table 12 is a member made of an aluminum alloy and has a U-shaped cross section, and has a flat plate portion 14 that is rectangular in plan view, and a pair of side walls (a first side wall portion 16 and a second side wall portion 18) that protrude downward from a pair of opposing sides of the flat plate portion 14. As will be described later, inner surfaces 16a, 18a of these side walls 16, 18 are reference surfaces for improving the straightness of a table side guide member 24, and are finished to a highly accurate flat surface (see FIG. 5). The upper surface of the slide table 12 is a flat surface on which a workpiece can be mounted.

[0014] 5, the lower surface of the flat plate portion 14 has a pair of first bottom surfaces 14a adjacent to the side wall portions 16, 18, and a second bottom surface 14c continuing from the first bottom surface 14a via a step surface 14b. The distance from the upper surface of the flat plate portion 14 to the first bottom surface 14a is greater than the distance from the upper surface of the flat plate portion 14 to the second bottom surface 14c, and the second bottom surface 14c forms a gap into which the upper portion of the air cylinder side guide member 30 fits. As will be described later, the first bottom surface 14a is a reference surface for improving the straightness of the table side guide member 24, and is finished to a highly accurate flat surface.

[0015] A first mounting groove 20 and a second mounting groove 22 for mounting a table side guide member 24 are provided on the inside of the first side wall portion 16 and the second side wall portion 18. These mounting grooves 20, 22 are defined by the first bottom surface 14a of the flat plate portion 14 and the inner surfaces 16a, 18a of the side walls 16, 18 that are perpendicular to the first bottom surface 14a.

[0016] The first side wall 16 is provided with a plurality of screw holes 16c penetrating in the left-right direction, lined up in the longitudinal direction of the first side wall 16. Set screws 26 are inserted and screwed into the screw holes 16c from the outer surface 16b of the first side wall 16, and their tips abut against the outer surface 24a of the table side guide member 24. In this embodiment, a total of six set screws 26 are used. The second side wall 18 is not provided with a screw hole.

[0017] The slide table 12 is provided with a plurality of fastening bolt insertion holes 14d that penetrate the flat plate portion 14 in the vertical direction and whose lower ends open to the first bottom surface 14a (see FIG. 4). The plurality of fastening bolt insertion holes 14d are arranged side by side in the longitudinal direction of the first bottom surface 14a. A step is formed in the middle of each fastening bolt insertion hole 14d against which the head of a fastening bolt 28 abuts (see FIG. 3).

[0018] As shown in Figures 4 and 5, the table side guide member 24 is a long member with a rectangular cross section, and is attached to the first mounting groove 20 and the second mounting groove 22 so that its outer surface 24a matches the inner surfaces 16a, 18a of each side wall portion 16, 18 of the slide table 12, and its top surface 24b matches the first bottom surface 14a of the slide table 12.

[0019] A convex portion 24c extending over the entire longitudinal length of the table side guide member 24 is provided on the inner surface of the table side guide member 24, and a first rolling surface 24d and a second rolling surface 24e along which the balls 36 can roll are formed on the upper and lower sides of the convex portion 24c, respectively.

[0020] The table side guide member 24 is provided with a plurality of fastening bolt mounting holes 24f penetrating in the vertical direction at positions aligned with the fastening bolt insertion holes 14d of the slide table 12. The fastening bolts 28 are inserted into the fastening bolt insertion holes 14d from the upper surface of the slide table 12 and screwed into the fastening bolt mounting holes 24f of the table side guide member 24. The fastening bolts 28 serve to fix the table side guide member 24 to the slide table 12. In this embodiment, each table side guide member 24 is fixed to the slide table 12 by three fastening bolts 28 aligned in the longitudinal direction of the table side guide member 24.

[0021] The axis of the fastening bolt 28 screwed into the fastening bolt mounting hole 24f and the axis of the set screw 26 screwed into the screw hole 16c are perpendicular to each other when viewed from the direction along the sliding direction of the slide table 12 (see Figure 3).

[0022] The table side guide member 24 is made of heat-treated steel. The manufacturing process of the table side guide member 24 includes a process of forming a bar-shaped or plate-shaped material into a predetermined cross-sectional shape by rolling, and a process of subjecting the formed product to heat treatment by quenching and tempering. Among the rolling processes, cross rolling is suitable for manufacturing the table side guide member 24.

[0023] Cross rolling is a rolling process in which compressive forces are applied in two mutually perpendicular directions by two pairs of work rolls, and is useful for obtaining a formed product with a smooth surface. On the other hand, cross rolling is not suitable for obtaining a formed product with a large cross-sectional area, but since the table side guide member 24 is a member with a small cross-sectional area, it can be easily formed by cross rolling.

[0024] The heat treatment by quenching / tempering of the molded product of the table side guide member 24 is performed in order to impart the necessary hardness to the first rolling surface 24d and the second rolling surface 24e of the table side guide member 24. This heat treatment makes the table side guide member 24 into a martensitic structure. The table side guide member 24, which is long and has a small cross-sectional area, will warp due to this heat treatment and lose straightness, but a method for improving this will be described later. Note that tempering after quenching is not necessarily performed, but it is preferable to perform tempering in order to restore toughness.

[0025] The air cylinder side guide member 30 is a member having a rectangular cross section, and its length along the sliding direction of the slide table 12 is shorter than that of the table side guide member 24. On one side surface 30a of the air cylinder side guide member 30, a first rolling surface 32a and a second rolling surface 32b on which the balls 36 can roll are formed side by side vertically. On the other side surface 30b of the air cylinder side guide member 30, a third rolling surface 32c and a fourth rolling surface 32d on which the balls 36 can roll are formed side by side vertically (see FIG. 3). The air cylinder side guide member 30 is provided with a pair of fixing bolt attachment holes 30c penetrating in the vertical direction.

[0026] As shown in FIG. 3, the air cylinder side guide member 30 includes a first circulation passage through which the balls 36 can circulate. hole 34a or 4th Circulation hole The first rolling contact surface 32a to the fourth rolling contact surface 32d of the air cylinder side guide member 30 are provided at both ends with first circulation grooves 34a, 34b, 34c, 34d, respectively. hole 34a or 4th Circulation hole Connected to 34d.

[0027] A plurality of balls 36 provided between the first rolling surface 24d of one of the table side guide members 24 and the first rolling surface 32a of the air cylinder side guide member 30 facing thereto roll on these rolling surfaces and form a first circulation hole A plurality of balls 36 provided between the second rolling surface 24e of one of the table side guide members 24 and the second rolling surface 32b of the air cylinder side guide member 30 facing the second rolling surface 24e roll on these rolling surfaces and circulate in the second circulation path 34a as the slide table 12 slides. hole Cycle through 34b.

[0028] Similarly, a plurality of balls 36 provided between the first rolling surface 24d of the other table side guide member 24 and the third rolling surface 32c of the air cylinder side guide member 30 facing thereto roll on these rolling surfaces and form a third circulation hole 34c, and a plurality of balls 36 provided between the second rolling surface 24e of the other table side guide member 24 and the fourth rolling surface 32d of the air cylinder side guide member 30 facing thereto roll on these rolling surfaces and form a fourth circulation hole Circulates 34d.

[0029] As described above, the slide table 12 is supported by the air cylinder 38 by a structure in which a plurality of balls 36 are arranged in two rows between the air cylinder side guide member 30 and each table side guide member 24, i.e., a support structure called a circular arc.

[0030] The air cylinder side guide member 30 is made of heat-treated steel, similar to the table side guide member 24. hole 34a or 4th Circulation hole The air cylinder side guide member 30 on which 34d is provided has a large cross-sectional area, so that warping is small even when the molded product is subjected to heat treatment.

[0031] The air cylinder 38 includes a cylinder tube 40 having a pair of cylinder chambers and pistons (neither shown) arranged in parallel inside. The ends of piston rods 42 connected to the pistons extend outward from the cylinder tube 40 and are connected to an end plate 44. The slide table 12 is also connected to the end plate 44 (see FIG. 4).

[0032] 4, a recess 40a is provided on the top surface of the cylinder tube 40 into which the lower part of the air cylinder side guide member 30 fits. The cylinder tube 40 also has a pair of fixing bolt insertion holes 40b that penetrate in the vertical direction and open into the recess 40a. A fixing bolt 46 is inserted into the fixing bolt insertion hole 40b from below the cylinder tube 40, and its tip is screwed into the fixing bolt attachment hole 30c of the air cylinder side guide member 30 that fits into the recess 40a of the cylinder tube 40. As a result, the air cylinder side guide member 30 is positioned and fixed to the cylinder tube 40.

[0033] When air is supplied to and exhausted from the cylinder chamber to drive the piston, the slide table 12 slides in the same direction as the piston. In this embodiment, the air cylinder 38 is used as an actuator for driving the slide table 12, but an electric motor may also be used.

[0034] Next, a method for improving the straightness of the table side guide member 24 will be described. As described above, the long table side guide member 24 with a small cross-sectional area warps when heat treated, reducing the straightness. This warp can be divided into a warp that curves in the left-right direction when the table side guide member 24 is attached to the slide table 12 and a warp that curves in the up-down direction. Below, we will explain the cases of correcting the warp in the left-right direction and the warp in the up-down direction.

[0035] (When correcting warpage in the left-right direction) 6 shows how the table side guide member 24 is curved so as to be convex inward within the first mounting groove 20 of the slide table 12, that is, how the table side guide member 24 is curved so that the longitudinal center portion is farther away from the inner surface 16a of the first side wall portion 16 than both longitudinal ends. Note that, for convenience, the warping of the table side guide member 24 is exaggerated in FIG. 6. To correct this warping, the amount by which the tips of the set screws 26 attached to the screw holes 16c of the first side wall portion 16 of the slide table 12 protrude toward the table side guide member 24 may be adjusted.

[0036] Specifically, with the cylinder tube 40 of the air cylinder 38 fixed to the floor surface or the like, the tip of a tool is inserted into the threaded holes 16c of the first side wall 16 from outside the first side wall 16 of the slide table 12 to rotate each set screw 26, thereby increasing the protruding amount of the set screws 26 located near both longitudinal ends of the table side guide member 24. At this time, the protruding amount of the set screws 26 located near the longitudinal center of the table side guide member 24 may also be adjusted to match the above protruding amount.

[0037] When the outer surface 24a of the table side guide member 24 is pressed by the multiple set screws 26, the inner surface receives a reaction force from the multiple balls 36 at the contact points with the balls 36. Therefore, by adjusting the protruding amount of the set screws 26 as described above, the straightness of the table side guide member 24 can be improved. In other words, the straightness of the table side guide member 24 in the first mounting groove 20 can be improved with reference to the inner surface 16a of the first side wall portion 16 of the slide table 12.

[0038] When the table side guide member 24 is curved so as to be convex outward within the first mounting groove 20 of the slide table 12, that is, when the table side guide member 24 is curved so that both longitudinal ends are farther away from the inner surface 16a of the first side wall portion 16 than the longitudinal center portion, the protruding amount of the set screw 26 located near the longitudinal center portion of the table side guide member 24 is increased. At this time, the protruding amount of the set screw 26 located near both longitudinal ends of the table side guide member 24 may also be adjusted to match the above protruding amount.

[0039] Furthermore, if the table side guide member 24 is curved so as to be convex inward or outward within the second mounting groove 22 of the slide table 12, the protruding amount of each set screw 26 can be increased. If the protruding amount of the set screws 26 is increased overall, the force with which the second side wall portion 18, which attempts to maintain the distance from the first side wall portion 16 due to the rigidity of the slide table 12, presses the table side guide member 24 within the second mounting groove 22 increases. Therefore, the straightness of the table side guide member 24 within the second mounting groove 22 is improved with respect to the inner surface 18a of the second side wall portion 18.

[0040] (When correcting vertical warpage) 7 shows how the table side guide member 24 is curved so as to be convex downward within the first mounting groove 20 or the second mounting groove 22 of the slide table 12, that is, how the table side guide member 24 is curved so that the longitudinal center portion is farther away from the first bottom surface 14a of the slide table 12 than the longitudinal ends. Note that, for convenience, the warping of the table side guide member 24 is exaggerated in FIG. 7. To correct this warping, the tightening amount of the fastening bolts 28 that fix the table side guide member 24 to the slide table 12 may be increased.

[0041] Specifically, when a tool is engaged with the head of each fastening bolt 28 facing the upper surface of the slide table 12 and the fastening bolt 28 is rotated in a predetermined direction, the distance between the back surface of the head of the fastening bolt 28 abutting against the step of the fastening bolt insertion hole 14d of the flat plate portion 14 and the upper surface 24b of the table side guide member 24 is narrowed. As a result, the upper surface 24b of the table side guide member 24 is pressed against the first bottom surface 14a of the slide table 12, improving the straightness of the table side guide member 24. In other words, the straightness of the table side guide member 24 is improved with respect to the first bottom surface 14a of the slide table 12.

[0042] Similarly, when the table side guide member 24 is curved so as to be convex upward within the first mounting groove 20 or the second mounting groove 22 of the slide table 12, that is, when the table side guide member 24 is curved so that both longitudinal ends are farther away from the first bottom surface 14a of the slide table 12 than the longitudinal center, the amount of tightening by each fastening bolt 28 can be increased.

[0043] The method for correcting the left-right and up-down warping of the table side guide member 24 has been described above. In the case of warping that has both left-right and up-down components, it can be corrected by combining adjustment with the set screws 26 and tightening with the fastening bolts 28. The fact that the table side guide member 24 is long and has a small cross-sectional area makes it easy to correct the warping. When correcting the warping when fitting the table side guide member 24 into the first mounting groove 20 or the second mounting groove 22 of the slide table 12, it is advisable to measure in advance the state of the warping of the table side guide member 24 after heat treatment (such as the direction of the warping).

[0044] Incidentally, the setscrews 26 also play a role in adjusting the preload on the balls 36. By increasing the protrusion amount of each setscrew 26, the preload on the balls 36 can be increased, and by decreasing the protrusion amount of each setscrew 26, the preload on the balls 36 can be decreased. There is an appropriate range for the magnitude of the preload on the balls 36, and if the preload falls below the appropriate range, rattle occurs, and if the preload exceeds the appropriate range, the sliding resistance of the slide table 12 becomes excessive.

[0045] The support structure called circular arc, which uses two rows of balls on each side, has a much better ball rolling resistance characteristic with respect to the ball preload than the support structure called gothic arch, which uses one row of balls on each side. That is, with the circular arc, the rolling resistance does not increase so much even if the ball preload increases.

[0046] As the set screw 26 corrects the left-right warping of the table side guide member 24, the preload on the balls 36 increases. However, since the slide table 12 is supported by the air cylinder 38 through a circular arc, even if the preload on the balls 36 increases, the increase in the sliding resistance of the slide table 12 can be suppressed as much as possible.

[0047] According to the linear guide mechanism of this embodiment, the straightness of the table side guide member 24 can be improved by the set screws 26 and the fastening bolts 28, so there is no need to perform grinding on the table side guide member 24 after heat treatment, and it is possible to eliminate any play when the slide table 12 slides.

[0048] In addition, since the table side guide member 24 does not have a circulation groove for the balls 36 and is a long member with a small cross-sectional area, the straightness of the table side guide member 24 can be easily improved by the set screws 26 and the fastening bolts 28.

[0049] The linear guide mechanism and linear actuator according to the present invention are not limited to the above-described embodiments, and it goes without saying that various configurations can be adopted without departing from the gist of the present invention. [Explanation of symbols]

[0050] 10...Linear actuator 12...Slide table (moving block) 16...First side wall part (side wall part) 16c...Screw hole 24...Table side guide member (moving block side guide member) 24a...Outer surface 26...Set screw 28…Fastening bolt 30...Air cylinder side guide member (actuator side guide member) 34a~34d...1st~4th cycle hole (circulation hole ) 36...Ball 38...Air cylinder (actuator)

Claims

1. A linear guide mechanism for slidably supporting a moving block on an actuator, the linear guide mechanism comprising: an actuator side guide member attached to the actuator; a pair of moving block side guide members attached to the moving block and arranged on either side of the actuator side guide member; and a plurality of balls arranged in two rows between the actuator side guide member and each of the moving block side guide members, the actuator side guide member being provided with a circulation hole through which the balls circulate, the moving block side guide member being made of heat-treated steel, and the moving block being provided with a pressing mechanism capable of adjusting the preload of the balls and improving the straightness of the moving block side guide member.

2. 2. The linear guide mechanism according to claim 1, The pressing mechanism is a set screw that is screwed into a threaded hole that penetrates a side wall portion of the moving block and has a tip that abuts against the outer surface of the moving block side guide member in a linear guide mechanism.

3. 3. The linear guide mechanism according to claim 2, The set screws are a linear guide mechanism arranged in a line in the longitudinal direction of the side wall portion of the moving block.

4. 3. The linear guide mechanism according to claim 2, A linear guide mechanism in which a fastening bolt is provided to fix the moving block side guide member to the moving block and improve the straightness of the moving block side guide member, and the axis of the fastening bolt and the axis of the set screw are in a perpendicular positional relationship to each other when viewed from a direction along the sliding direction of the moving block.

5. 5. The linear guide mechanism according to claim 4, The fastening bolts are arranged in a linear guide mechanism in a line in the longitudinal direction of the moving block side guide member.

6. 2. The linear guide mechanism according to claim 1, The linear guide mechanism includes a moving block side guide member which is a forged product produced by rolling.

7. 2. The linear guide mechanism according to claim 1, A linear guide mechanism in which the moving block side guide member is longer in a sliding direction of the moving block than the actuator side guide member.

8. 2. A linear actuator equipped with the linear guide mechanism according to claim 1, wherein an air cylinder is used as the actuator.

9. 2. A linear actuator equipped with the linear guide mechanism according to claim 1, wherein an electric motor is used as the actuator.

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