electric actuator

Abstract

An electric actuator (10) has an end plate (32) covering an end portion of a ball screw (14), a housing (34) through which the ball screw (14) penetrates, and a top cover (18) mounted to a first upper end surface (38) of the end plate (32) and a second upper end surface (40) of the housing (34) and covering an upper portion of the ball screw (14), a full length (L) of the top cover (18) in a longitudinal direction is longer than a gap (G) in the longitudinal direction of the end plate (32) and the housing (34), and the full length is shorter than a dimension (A) obtained by adding a length (S2) in the longitudinal direction of the second upper end surface (40) to the gap (G).

Description

Technical Field

[0001] This invention relates to an electric actuator. Background Technology

[0002] In automated production lines in factories, electric actuators are widely used for conveying workpieces. For example, Japanese Patent Application Publication No. 8-33264 discloses an electric actuator that drives a worktable via a ball screw. This electric actuator has a workpiece mounted on the worktable. Furthermore, to prevent foreign objects from getting caught in the ball screw, the ball screw is covered by a top cover.

[0003] In electric actuators, the top cover is sometimes removed from the housing for inspection during maintenance or troubleshooting. However, in conventional electric actuators, the top cover is covered by the workpiece. Therefore, removing the top cover requires taking the workpiece off the worktable, which presents a cumbersome operation. Summary of the Invention

[0004] The purpose of this invention is to solve the above-mentioned technical problems.

[0005] One aspect of the invention is an electric actuator comprising a ball screw extending along its long side; a drive unit that rotates the ball screw; a worktable driven by the ball screw; an end plate covering the end of the ball screw; a housing adjacent to the drive unit and through which the ball screw passes; and a top cover mounted on a first upper surface of the end plate and a second upper surface of the housing and covering the ball screw, wherein the total length L of the top cover in the long side direction is longer than the gap G between the end plate and the housing in the long side direction, and the total length is shorter than the dimension A obtained by adding the length S2 of the second upper surface in the long side direction to the gap G.

[0006] The electric actuator described above can remove the top cover without removing the workpiece from the worktable.

[0007] The above-mentioned objects, features, and advantages will be readily understood through the following description of embodiments with reference to the accompanying drawings. Attached Figure Description

[0008] Figure 1 This is a perspective view showing the electric actuator involved in the implementation method.

[0009] Figure 2 It means Figure 1 A side view of an electric actuator.

[0010] Figure 3 It means Figure 1 A side view of a modified example of the shell.

[0011] Figure 4 This is to explain Figure 1 The diagram shows the method of removing the top cover by sliding it in the first direction.

[0012] Figure 5 This means that in Figure 1 The diagram shows the removal direction of the electric actuator when there is an obstacle in the first direction.

[0013] Figure 6 This is to explain Figure 5 A diagram illustrating the process of detaching the top cover from the end plate.

[0014] Figure 7 This means to explain Figure 6 A diagram illustrating the operation of tilting and pulling out the top cover.

[0015] Figure 8 This is a perspective view of an electric actuator involved in a variation of the implementation method. Detailed Implementation

[0016] like Figure 1 and Figure 2 As shown, since the electric actuator 10 involved in the embodiment can perform high-speed and accurate operations, it is preferably used for wafer transport, for example, in a semiconductor manufacturing plant. The electric actuator 10 mounts a workpiece W (see reference 10) on a worktable 16 having a pair of fixing portions 28. Figure 4 It can be used for this purpose. As an example of workpiece W, a chuck for holding a wafer can be listed.

[0017] The details of the electric actuator 10 will be described below. In the following description, the terms "long side direction," "width direction," and "vertical direction" are used to describe the arrangement of the components of the electric actuator 10. These directions are orthogonal to each other. The long side direction is aligned with the extension direction of the ball screw 14, and the direction away from the drive section 12 is called the first direction (top direction), and its opposite direction is called the second direction (base direction). In the vertical direction, the direction from the linear guide 30 toward the top cover 18 is called the upper side or above, and its opposite direction is called the lower side or below. Furthermore, the terms "upper" and "lower" are used to describe the arrangement of the components of the electric actuator 10 and do not limit the arrangement direction of the electric actuator 10.

[0018] The electric actuator 10, as a main component, includes a drive unit 12, a ball screw 14, a worktable 16, and a top cover 18. The drive unit 12 has a motor 20 and a rotation transmission unit 22. The motor 20 rotates the ball screw 14. The rotation transmission unit 22 connects the rotation shaft of the motor 20 and the ball screw 14, transmitting the rotational motion of the motor 20 to the ball screw 14. The rotation transmission unit 22 has a box-shaped frame 22a. The frame 22a is formed, for example, from a transparent resin component, configured so that its internal state can be visually observed from the outside. If necessary, the rotation transmission unit 22 may also incorporate a reduction gear or the like. The frame 22a may also protrude upwards relative to the top cover 18.

[0019] The ball screw 14 extends along its long side. The end of the ball screw 14 in a second direction is inserted into the rotation transmission section 22 and rotates through the rotation transmission section 22. A threaded groove is formed on the outer peripheral surface of the ball screw 14. The worktable 16 is screwed onto the ball screw 14.

[0020] The worktable 16 engages with a linear guide 30 covering the lower and side portions of the ball screw 14. The linear guide 30 extends along its long side. The worktable 16 is guided by the linear guide 30 and slides along its long side. A pair of fixing portions 28 are provided on both sides in the width direction of the worktable 16. The pair of fixing portions 28 are separated in the width direction. For example, a tool for fixing a workpiece W (see reference) is provided in the fixing portion 28. Figure 4 The workpiece W is fixed by means of a pair of fixing parts 28.

[0021] An end plate 32 is joined to the end of the linear guide 30 in a first direction, and a housing 34 is joined to the end of the linear guide 30 in a second direction. The end plate 32 is a plate-shaped component that covers the end of the ball screw 14 in the first direction (the direction away from the drive unit 12) along a plane orthogonal to the long side. The end plate 32 supports the end of the ball screw 14 so that it can rotate via bearings or the like (not shown).

[0022] The end plate 32 has a first upper end surface 38 at its upper end. The first upper end surface 38 is a smooth surface without any upward protrusions, supporting the top cover 18 so that it can slide along its long side. The first upper end surface 38 is formed over a range from the end of the end plate 32 in a first direction to the end in a second direction.

[0023] The first upper end face 38 has a top surface 38a and a pair of side surfaces 38b. The top surface 38a is formed as a plane parallel to both the longitudinal and width directions. The side surfaces 38b are located on both sides of the top surface 38a and extend obliquely relative to the top surface 38a. The top surface 38a and the side surfaces 38b are respectively opposite to the cover plate portion 46 and the side wall portion 48 of the top cover 18. The end plate 32 has threaded holes at predetermined positions on the top surface 38a for fixing screws or bolts or other fixing components 44. The top cover 18 is fixed to the first upper end face 38 by fixing components 44.

[0024] The housing 34 is located between the linear guide 30 and the drive unit 12, and is adjacent to the drive unit 12. The ball screw 14 extends through the housing 34 and in a second direction. The housing 34 supports the ball screw 14 for rotation via bearing components such as bearings.

[0025] The housing 34 also has a second upper end face 40 and a protrusion 42. The second upper end face 40 is formed at the upper end of the housing 34. The second upper end face 40 has a top surface 40a and a pair of side surfaces 40b. The top surface 40a is formed as a plane parallel to the longitudinal and width directions and is held by the pair of side surfaces 40b. The side surfaces 40b are located on both sides of the top surface 40a and extend obliquely in the vertical direction relative to the top surface 40a. The top surface 40a and the side surfaces 40b are opposite to the inner surface of the top cover 18. The housing 34 has screw holes at a predetermined position on the top surface 40a for fixing screws or bolts or other fixing components 44 for fixing the top cover 18. The second upper end face 40 is formed as a smooth surface without an upwardly protruding protrusion, supporting the top cover 18 so that it can slide along the longitudinal direction. The second upper end face 40 is formed over a range from the end of the housing 34 in a first direction to the protrusion 42. The length S2 of the second upper end face 40 in the long side direction is longer than the length S1 of the first upper end face 38 of the end plate 32 in the long side direction.

[0026] The protrusion 42 is located near the end of the housing 34 in the second direction and protrudes upward relative to the second upper end face 40. The protrusion 42 is adjacent to the drive portion 12 and abuts against the rotation transmission portion 22 of the drive portion 12. The second upper end face 40 extends in the second direction to the portion reaching the protrusion 42. The length S2 of the long side of the second upper end face 40 is the length in the long side direction from the end of the housing 34 in the first direction to the boundary between the second upper end face 40 and the protrusion 42. Furthermore, as... Figure 3 As shown, the housing 34A in another embodiment may also not have the protrusion 42. In this case, in the housing 34A, the second upper end face 40 extends to the end of the housing 34 in a second direction. Figure 3 The length S2 of the second upper end face 40 in the long side direction is the distance in the long side direction from the end of the housing 34 in the first direction to the boundary between the second upper end face 40 and the drive part 12.

[0027] like Figure 1 and Figure 2 As shown, the top cover 18 is a plate-shaped component extending along its long side, covering the top of the ball screw 14. The top cover 18 has a cover plate portion 46 and a pair of side wall portions 48. The cover plate portion 46 is formed as a plane parallel to both the width direction and the long side direction. The side wall portions 48 are respectively provided on both sides of the cover plate portion 46 in the width direction, extending downward from the cover plate portion 46. The lower surface of the cover plate portion 46 faces the top surfaces 38a and 40a, and the inner side of the side wall portions 48 faces the side surfaces 38b and 40b.

[0028] like Figure 2 As shown, the first end of the top cover 18 rests on the first upper end face 38 of the end plate 32 and is fixed to the end plate 32 by a fixing member 44 in a manner that covers the first upper end face 38. The second end of the top cover 18 rests on the second upper end face 40 of the housing 34 and is fixed to the housing 34 by a fixing member 44 in a manner that covers the second upper end face 40. By removing the fixing member 44, the fixation of the top cover 18 relative to the end plate 32 and the housing 34 is released.

[0029] The length of the top cover 18 from its end in the first direction to its end in the second direction is referred to in this specification as the total length L of the long side of the top cover 18. The total length L of the long side of the top cover 18 is longer than the gap G between the end plate 32 and the housing 34 in the long side direction. In addition, the total length L of the long side of the top cover 18 is shorter than the dimension A obtained by adding the length S2 of the second upper end face 40 of the housing 34 in the long side direction to the gap G. With the top cover 18 fixed by the fixing member 44, the end of the top cover 18 in the second direction is separated from the protrusion 42 in the long side direction.

[0030] The electric actuator 10 in this embodiment is configured as described above. The operation of the electric actuator 10 will be explained below.

[0031] like Figure 4 As shown, the electric actuator 10 is used by mounting a workpiece W on the fixing part 28 of the worktable 16. When the top cover 18 is removed, the fixing part 44 is removed to release the fixing state of the top cover 18. Then, as shown, an operation is performed to slide the top cover 18 in a first direction along the long side. As a result, the top cover 18 slides along the long side under the workpiece W and can be removed without removing the workpiece W from the worktable 16.

[0032] like Figure 5 As shown, depending on the configuration position of the electric actuator 10, sometimes an obstacle 50 is adjacent to the electric actuator 10 in the first direction. In such cases, it is impossible to perform... Figure 4Such an operation involves sliding the top cover 18 in the first direction. However, since the top cover 18 interferes with the drive unit 12 located in the second direction, it cannot be pulled out simply by sliding the top cover 18 in the second direction.

[0033] Therefore, in Figure 5 In this case, the top cover 18 is removed by the following operation. First, as shown in the figure, the worktable 16 is moved in the first direction and positioned as close as possible to the end plate 32. Next, all the fixing parts 44 that secure the top cover 18 are removed.

[0034] Next, the top cover 18 is slid in the second direction. The sliding of the top cover 18 in the second direction is limited by the protrusion 42. However, the total length L of the top cover 18 is shorter than the dimension A obtained by adding the length S2 of the second upper end face 40 of the housing 34 in the long side direction to the gap G (see reference). Figure 2 Therefore, as Figure 6 As shown, before the sliding of the top cover 18 in the second direction is restricted by the protrusion 42, the end of the top cover 18 in the first direction disengages from the end plate 32 and falls toward the ball screw 14. As a result, the top cover 18 is tilted with the end in the first direction lower and the end in the second direction higher.

[0035] As a result, the vertical gap between the top cover 18 and the workpiece W widens, and the extension line 52 of the top cover 18 (the extension line of the lower end of the side wall portion 48) extends obliquely upward. By utilizing the gap between the top cover 18 and the workpiece W, the second-direction end of the top cover 18 is further lifted upward, and the extension line 52 of the top cover 18 passes above the drive portion 12 as shown. Subsequently, as Figure 7 As shown, by maintaining Figure 6 While tilting, the top cover 18 is pulled out along the extension line 52, and the top cover 18 can be removed without removing the workpiece W from the worktable 16.

[0036] (Modifications of the implementation method)

[0037] In the above embodiments, in the illustrated example, the drive unit 12 has a motor 20 and a rotation transmission unit 22 arranged side by side in the long side direction, but the drive unit 12 in this embodiment is not limited to this arrangement.

[0038] like Figure 8Like the electric actuator 10A in the modified example, the drive unit 12 may also have a motor 20 arranged adjacent to the side portion of the ball screw 14 in the width direction. In this case, the rotational motion of the motor 20 is transmitted to the ball screw 14 via a rotation transmission unit 22A extending in the width direction. The rotation transmission unit 22A has a frame 22b extending in the width direction, which is configured to cover the end of the motor 20 and the base end of the ball screw 14 from a second direction. The rotation transmission unit 22A transmits the rotational motion of the motor 20 to the ball screw 14 via an internal belt and pulley. The frame 22b is formed of transparent resin, configured so that its interior can be visually observed from the outside. Due to the other structures of the electric actuator 10A and Figure 1 The electric actuator 10 shown is the same, so its detailed description is omitted.

[0039] The following notes are also disclosed regarding the above-described embodiments.

[0040] (Note 1)

[0041] The electric actuator 10 of the present invention includes: a ball screw 14 extending along its long side; a drive unit 12 that rotates the ball screw; a worktable 16 driven by the ball screw; an end plate 32 covering the end of the ball screw; a housing 34 adjacent to the drive unit and through which the ball screw passes; and a top cover 18 mounted on a first upper surface 38 of the end plate and a second upper surface 40 of the housing and covering the ball screw, wherein the total length L of the top cover in the long side direction is longer than the gap G between the end plate and the housing in the long side direction, and the total length is shorter than the dimension A obtained by adding the length S2 of the second upper surface in the long side direction to the gap.

[0042] The aforementioned electric actuator can slide and remove the top cover in either the first or second direction along the long side without removing the workpiece from the worktable.

[0043] (Note 2)

[0044] According to the electric actuator described in Appendix 1, it may also have a fixing member 44 that fixes the top cover to the end plate and the housing, and the top cover fixed by the fixing member is separated from the drive unit in the long side direction. This electric actuator can cause the end of the top cover in a first direction to detach from the end plate and fall down by sliding the top cover toward the drive unit.

[0045] (Note 3)

[0046] According to the electric actuator described in Appendix 2, the first upper end face of the end plate and the second upper end face of the housing may support the top cover so that it can slide along the long side. This electric actuator allows the top cover to be removed smoothly.

[0047] (Note 4)

[0048] According to the electric actuator described in Appendix 3, the length S2 of the long side of the second upper end face may also be longer than the length S1 of the long side of the first upper end face. This electric actuator can increase the range of sliding of the top cover in the second direction, and can further reliably remove the top cover.

[0049] (Note 5)

[0050] According to the electric actuator described in Appendix 3 or 4, when the fixing component is removed and the top cover is slid toward the drive unit, the top cover detaches from the end plate and tilts as it falls toward the ball screw. This electric actuator allows the top cover to be removed even in the presence of surrounding obstacles by tilting and sliding the top cover.

[0051] (Note 6)

[0052] According to the electric actuator described in Appendix 5, the drive unit may also protrude upward relative to the second upper end face of the housing, and the extension line 52 of the inclined top cover passes above the drive unit. This electric actuator allows the top cover to be removed without obstruction from the drive unit by sliding the top cover while it is tilted.

[0053] (Note 7)

[0054] According to the electric actuator described in Appendix 6, the top cover may also have a cover plate portion 46 and a pair of side wall portions 48. The cover plate portion is parallel to the linear guide rail 30, and the pair of side wall portions protrude downwards from both sides of the cover plate portion in the width direction. The first upper end surface of the end plate and the second upper end surface of the housing respectively have top surfaces 38a and 40a and a pair of side surfaces 38b and 40b. The top surface faces the cover plate portion, and the pair of side surfaces face the pair of side wall portions from the inside. This electric actuator can remove the top cover while preventing displacement in the width direction, thus making the loading and unloading of the top cover easier.

[0055] Although the present invention has been described in detail, it is not limited to the individual embodiments described above. Various additions, substitutions, modifications, and partial deletions can be made to these embodiments without departing from the spirit of the invention, or from the spirit of the invention derived from the scope of the patent claims and their equivalents. Furthermore, these embodiments can also be implemented in combination. For example, in the embodiments described above, the order of each action and each process is shown as an example and is not limited to these orders. The same applies to instances where numerical values ​​or formulas are used in the description of the embodiments described above.

Claims

1. An electric actuator (10), characterized in that, have: A ball screw (14) extends along its long side; Drive unit (12) that causes the ball screw to rotate; Worktable (16), which is driven by the ball screw; End plate (32) that covers the end of the ball screw; Housing (34), which is adjacent to the drive unit and through which the ball screw passes; and A top cover (18) is mounted on the first upper end face (38) of the end plate and the second upper end face (40) of the housing and covers the top of the ball screw. The total length (L) of the long side of the top cover is longer than the gap (G) between the end plate and the housing in the long side direction, and the total length is shorter than the dimension (A) obtained by adding the length (S2) of the long side of the second upper end face to the gap.

2. The electric actuator according to claim 1, characterized in that, It has a fixing component (44) that fixes the top cover to the end plate and the housing, and the top cover fixed by the fixing component is separated from the drive unit in the long side direction.

3. The electric actuator according to claim 2, characterized in that, The first upper end face of the end plate and the second upper end face of the housing support the top cover so that it can slide along the long side.

4. The electric actuator according to claim 3, characterized in that, The length (S2) of the long side of the second upper surface is longer than the length (S1) of the long side of the first upper surface.

5. The electric actuator according to claim 3 or 4, characterized in that, When the fixing component is removed and the top cover is slid toward the drive unit, the top cover detaches from the end plate and tilts as it falls toward the ball screw.

6. The electric actuator according to claim 5, characterized in that, The drive unit protrudes upward relative to the second upper end face of the housing, and the extension line (52) of the inclined top cover passes over the drive unit.

7. The electric actuator according to claim 6, characterized in that, The top cover has a cover plate portion (46) and a pair of side wall portions (48). The cover plate portion is parallel to the linear guide rail (30), and the pair of side wall portions protrude downward from both sides of the cover plate portion in the width direction. The first upper end face of the end plate and the second upper end face of the housing respectively have a top surface (38a, 40a) and a pair of side surfaces (38b, 40b), the top surface being opposite to the cover plate portion and the pair of side surfaces being opposite to the pair of side wall portions from the inside.

Images