JP5251435B2 - Clean robot - Google Patents

Description

  The present invention relates to a clean robot in which dust is not released to the outside by sucking outside air into a bellows-like cover covering a linear motion shaft.

For example, vertical articulated robots and Cartesian coordinate robots employ linear motion axes that move linearly up and down as tool axes to which a hand or the like is attached. When configuring a robot equipped with this linear motion shaft as a clean robot installed in an assembly plant for semiconductors, electronic devices, etc., the linear motion shaft is covered with a bellows-shaped cover, and the inside of the robot is made into a bellows shape by applying negative pressure. Outside air is sucked into the cover so that dust is not released from the linear motion shaft to the outside (for example, Patent Document 1).
JP-A-11-138488

  The bellows-shaped cover expands and contracts as the linear motion shaft moves up and down, and the pressure in the bellows-shaped cover changes depending on the expansion and contraction. In order to prevent the dust from being released from the bellows-like cover, it is necessary to keep the internal pressure of the bellows-like cover at a pressure (negative pressure) lower than the atmospheric pressure at all times. For this purpose, it is necessary to increase the amount of air sucked from the bellows-like cover so that the negative pressure is maintained even when the internal pressure is increased when the bellows-like cover is contracted. However, if the amount of air sucked from the bellows-shaped cover is increased, conversely, when the bellows-shaped cover is extended, the internal pressure thereof is too low, and the bellows-shaped cover may be abnormally deformed.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a clean robot capable of preventing abnormal deformation of a bellows-like cover covering a linear motion shaft.

According to the first aspect of the present invention , at least a part of the intake passage can be configured by using a ball bearing necessary for connecting the non-rotating bellows-like cover to the rotating linear motion shaft, thereby reducing cost.
In the first aspect , since the flange covers the ball bearing, dust generated in the bellows-like cover is less likely to enter the ball bearing.
According to claim 2 , since the passage area of the inner communication passage of the intake passage is narrower than the passage area of the chamber, a pressure loss occurs between the chamber and the bellows-like cover. The change in quantity can be reduced.

  Hereinafter, an embodiment in which the present invention is applied to a clean robot including a horizontal articulated (four-axis) type robot will be described with reference to the drawings. FIG. 3 shows an external configuration of the main body 1 of the clean robot. The main body 1 includes a base 2 fixed to an installation surface, a first arm 3 connected to the base 2 so as to be pivotable about a vertical axis J1, and a vertical axis J2 at the tip of the first arm 3. The second arm 4 is connected to be pivotable about the first arm 4 and the linear motion shaft 5 is provided at the tip of the second arm 4 so as to be movable up and down and rotatable. A tool such as a hand (not shown) is detachably attached to the lower end portion of the linear motion shaft 5.

  FIG. 2 shows the internal configuration of the second arm 4. As shown in FIG. 2, the second arm 4 is mainly composed of a frame 6, on which a second arm 4 for turning the second arm 4 with respect to the first arm 3 is placed. A biaxial motor 7, a third axial motor 8 for rotating the linear motion shaft 5, and a fourth axial motor (not shown) for vertically moving the linear motion shaft 5 are fixed. Each of the second shaft motor 7, the third shaft motor 8, and the fourth shaft motor is provided with an electromagnetic brake 9 (only the third shaft motor 8 is shown).

  Further, a nut 10 of a ball screw mechanism and a sleeve 11 of a ball spline mechanism are rotatably disposed at the front end portion of the frame 6 so as to be positioned vertically on the same axis. Pulleys 12 and 13 are attached to the nut 10 and the sleeve 11, respectively, and these pulleys 12 and 13 are connected to a third shaft motor 8 and a fourth shaft motor (not shown) by belt transmission mechanisms 14 and 15, respectively. Has been.

  On the other hand, the linear motion shaft 5 is composed of a ball screw spline shaft, and a screw groove 5a and a spline groove 5b are formed on the outer periphery thereof. The linear motion shaft 5 is fitted to a nut 10 and a sleeve 11, and a thread groove 5 a is engaged with the nut 10 and a spline groove 5 b is engaged with the sleeve 11. When the third shaft motor 8 is started, the sleeve 11 is rotated via the belt transmission mechanism 14, and the rotation of the sleeve 11 causes the linear motion shaft 5 to rotate as indicated by an arrow A in FIG. 3. When a fourth shaft motor (not shown) is started, the nut 10 is rotated via the belt transmission mechanism 15 so that the linear motion shaft 5 moves up and down as indicated by the arrow B in FIG. It has become.

  The upper side of the frame 6 is covered with a detachable hood 16 attached to the frame 6. Accordingly, the second shaft motor 7, the third shaft motor 8, and the fourth shaft disposed on the frame 6. The shaft motor (not shown), the nut 10, the sleeve 11, the belt transmission mechanisms 14 and 15, etc. are all housed in the second arm 4 including the frame 6 and the hood 16. However, the upper and lower sides of the linear movement shaft 5 protrude outward from the circular openings 17 and 18 formed in the hood 16 and the frame 6, respectively, and the protruding portions on the upper and lower sides of the linear movement shaft 5 are bellows. Covers 19 and 20 are covered.

  In the present embodiment, when the inside of the main body 1 is set to a negative pressure, and there is a gap in each part, dust or the like generated in the main body 1 comes out to the outside by sucking outside air into the main body 1 from the gap. So that there is no. For this purpose, the air in the base 2 is sucked by an intake device (intake means) 21 such as a blower shown in FIG. Since the inside of the first arm 3 communicates with the base 2 and the inside of the second arm 4 communicates with the first arm 3, the inside of the base 2 is set to a negative pressure, so The inside of the arm 4 is also made negative pressure. The bellows-shaped covers 19 and 20 are connected at one end to the openings 17 and 18 as described later, so that when the second arm 4 has a negative pressure, the bellows-shaped covers 19 and 20 also have a negative pressure. Thus, the air in the bellows-shaped covers 19 and 20 is prevented from leaking outside.

  Here, the mounting configuration of the two bellows-shaped covers 19 and 20 will be described with reference to FIGS. Since the upper and lower relations are the same in both the bellows-like covers 19 and 20, the upper and lower bellows-like covers 19 will be described here. The description of 20 is omitted.

  That is, as shown in FIG. 1, the upper end portion of the linear motion shaft 5 has a slightly smaller diameter, and the ball bearing 22 is fitted to the lower end portion of the small diameter portion 5c. The small diameter portion 5c at the upper end of the linear motion shaft 5 is formed with a male screw, and the nut 24 is screwed into the male screw after the ring 23 is fitted to the small diameter portion 5c. By tightening the nut 24, the inner race 22a of the ball bearing 22 is fastened and fixed between the lower end step portion of the small diameter portion 5c and the nut 24.

  Moreover, as shown in FIG. 2, the peripheral part of the opening part 17 of the food | hood 16 is formed in the cylinder shape. And the attachment cylinder part 19a of the lower end of the bellows-like cover 19 and the attachment cylinder part 19b of the upper end are fitted to the outer periphery of the cylindrical part 17a of the opening part 17 and the outer periphery of the outer race 22b of the ball bearing 22, respectively. (Tightening members) 25 and 26 are tightened. Accordingly, the inside of the bellows-shaped cover 19 is communicated with the second arm 4 through the opening 17. The lower bellows-shaped cover 20 communicates with the second arm 4 through the opening 18 and a passage 6a formed in the wall portion of the frame 6, as shown in FIG.

  A flange 27 is formed integrally with the upper portion of the linear motion shaft 5 in the vicinity of the lower side of the ball bearing 22. A narrow gap is formed between the flange 27 and the outer race 22 b of the ball bearing 22, and this gap is continuous in the bellows-shaped cover 19. The ball bearing 22 has a gap between a plurality of balls 22c existing between the outer race 22b and the inner race 22a. The gap between the balls 22c is connected to the outside atmosphere, and is also connected to the bellows-shaped cover 19 through a gap between the flange 27 and the outer race 22b.

  Therefore, when negative pressure is applied to the bellows-shaped cover 19 side of the ball bearing 22, the outside air is sucked to the bellows-shaped cover 19 side through the gap between the balls 22c and the gap between the flange 27 and the outer race 22b. As described above, the gap between the balls 22 c and the gap between the flange 27 and the outer race 22 b existing at the projecting end portion of the linear motion shaft 5 from the second arm 4 function as an intake path 28 for the outside air. A gap between the balls 22c (a gap between the outer race 22b and the inner race 22a) constitutes a part of the intake passage 28, and constitutes an outer communication passage 29 communicating with the outside of the intake passage 28. To do.

  An annular recess that opens into the gap between the flange 27 and the ball bearing 22 is formed on the upper surface portion (end surface portion) of the flange 27. The recess functions as a chamber 30 that is located in the middle of the intake passage 28 and into which the outside air sucked through the outer communication passage 29 temporarily flows. The outside air that has flowed into the chamber 30 flows into the bellows-shaped cover 19 through a narrow gap between the flange 27, the outer race 22 b, and the bellows-shaped cover 19 when the inside of the bellows-shaped cover 19 is at a lower pressure than within the chamber 30. . Conversely, when the inside of the bellows-shaped cover 19 has a higher pressure than the inside of the chamber 30, the air in the bellows-shaped cover 19 flows into the chamber 30 through a narrow gap between the flange 27, the outer race 22 b and the bellows-shaped cover 19. .

  The narrow gap between the flange 27 and the outer race 22b and the bellows-like cover 19 functions as an inner communication passage 31 communicating with the inside of the bellows-like cover 19 in the intake passage 28. The passage area of the inner communication path 31 is smaller than the passage area of the chamber 30, and when air flows through the inner communication path 31, a pressure loss corresponding to the flow rate occurs. The passage area of the outer communication passage 29 described above is also smaller than the passage area of the chamber 30.

The linear motion shaft 5 is formed with a suction path 32 penetrating the linear motion shaft 5 vertically at the center thereof. The upper end of the suction path 32 is in communication with a rotary pipe joint 33 attached to the upper end portion of the linear motion shaft 5. A hose 34 connected to the intake device 21 is connected to the rotary pipe joint 33 so that air in the suction path 32 can be sucked by the intake device 21. In addition, the lower end opening of the suction path 32 at the lower end of the linear motion shaft 5 is closed by a plug (not shown).
The flange 27 of the linear motion shaft 5 is formed with a plurality of connection paths 35 for communicating the chamber 30 with the suction path 32. Therefore, when the suction path 32 is set to a negative pressure, the air in the chamber 30 is sucked into the suction path 32 through the connection path 35.

Next, the operation of the above configuration will be described. This description of the operation is centered on the upper and lower accordion-shaped covers 19, 20; The description of the lower bellows-shaped cover 20 is omitted.
When the intake device 21 is driven, the intake device 21 sucks air in the main body 1 and the suction path 32 of the linear motion shaft 5 to make negative pressure. For this reason, the air in the bellows-shaped cover 19 is also sucked into the second arm 4 through the opening 17, and as a result, the bellows-shaped cover 19 also has a negative pressure. Accordingly, not only the main body 1 but also the bellows-shaped cover 19 does not leak air to the outside.

  On the other hand, when the suction path 32 becomes negative pressure, the air in the chamber 30 is sucked into the suction path 32 through the connection path 35. The air in the chamber 30 is sucked into the suction path 32, and the inside of the bellows-shaped cover 19 becomes negative pressure, whereby the inside of the chamber 30 is made negative pressure. Then, due to the negative pressure in the chamber 30, outside air is sucked into the intake passage 28 from the outer communication passage 29. The outside air sucked into the chamber 30 is sucked into the suction path 32 from the connection path 35. At this time, when the internal pressure of the bellows-shaped cover 19 is lower than the internal pressure of the chamber 30, a part of the outside air sucked into the chamber 30 flows into the bellows-shaped cover 19 through the inner communication path 31.

When the linear motion shaft 5 is raised in this state, the bellows-like cover 19 is extended and its internal volume is increased, so that the air in the second arm 4 is sucked into the bellows-like cover 19 through the opening 17. Since the passage area of the opening 17 is relatively narrow, the amount of intake air through the opening 17 is insufficient, and as a result, the pressure in the bellows-shaped cover 19 decreases. On the contrary, when the linear motion shaft 5 is lowered, the bellows-like cover 19 contracts and its internal volume decreases, so that the air in the bellows-like cover 19 is discharged into the second arm 4 through the opening 17. For the same reason, the amount of air exhausted through the opening 17 is insufficient, so that the pressure in the bellows-shaped cover 19 increases.
If the pressure in the chamber 30 (intake passage 28) is maintained in a negative pressure state when the pressure in the bellows-like cover 19 rises during the rise and fall of the linear motion shaft 5, the bellows-like cover 19 It can be ensured that the air on the side does not leak outside through the outer communication passage 29.

  Now, when the pressure in the bellows-shaped cover 19 rises when the linear motion shaft 5 is lowered and becomes higher than the pressure in the chamber 30, the air in the bellows-shaped cover 19 passes through the inner communication path 31 into the chamber 30. Flowing. At this time, since the inner communication path 31 is narrow, a considerable pressure loss occurs. Therefore, in order to prevent the air in the bellows-like cover 19 from leaking outside through the outer communication passage 29, the inside of the bellows-like cover 19 when the linear motion shaft 5 is lowered while the intake device 21 is stopped. The pressure obtained by subtracting the negative pressure in the second arm 4 due to air suction of the intake device 21 and the pressure loss when the air in the bellows-shaped cover 19 flows through the inner communication path 31 from the maximum pressure of It may be less than atmospheric pressure. In this case, the pressure in the chamber 30 is reduced to the same level as the pressure in the second arm 4 because the pressure is reduced to the negative pressure by the same intake device 21 that makes the second arm 4 negative.

  From the above, the negative pressure in the second arm 4 is greater than that in the case where the flange 27, the chamber 30, the inner communication path 31, the suction path 32, and the connection path 35 are not provided (conventional). The total pressure may be increased by the pressure loss when circulating. This is shown in FIG. In FIG. 4A, a line C represents a change in pressure in the bellows-shaped cover 19 due to the vertical movement of the linear motion shaft 5 in a state where the intake device 21 has stopped the intake function, and a line D is due to air suction of the intake device 21. The negative pressure in the second arm 4 (the bellows-shaped cover 19), the line E is the negative pressure in the chamber 30 due to the suction of the suction passage 32, and the line F is the inner communication path along with the expansion and contraction of the bellows-shaped cover 19. This is the pressure loss when circulating 31. The line F changes in conjunction with the pressure change in the bellows-shaped cover 19 because the speed of the air flow through the inner communication path 31 changes due to the pressure change in the bellows-shaped cover 19. The line F defines the negative direction when the pressure in the chamber 30 is lower than the pressure in the bellows-shaped cover 19.

In FIG. 4B, the line G represents the line C in FIG. 4A (pressure in the bellows-shaped cover 19 accompanying expansion and contraction) and the line D (inside the bellows-shaped cover 19 due to negative pressure in the second arm 4). 4) and the actual pressure change in the bellows-shaped cover 19 due to expansion and contraction, and line H represents line G and line F (pressure loss in the inner communication path 31) in FIG. And the pressure in the chamber 30 is shown.
4B, even if the pressure in the bellows-shaped cover 19 is higher than the atmospheric pressure (indicated by 0 in FIG. 4), the pressure in the chamber 30 is lower than the atmospheric pressure. Can be maintained, the air on the bellows-shaped cover 19 side does not leak to the outside (in the atmosphere) through the outer communication passage 29.

  As described above, according to the present embodiment, the negative pressure in the second arm 4 can be made higher than the conventional pressure by the pressure loss when air flows through the inner communication path 31. For this reason, even if the bellows-like cover 19 extends and the internal pressure decreases when the linear motion shaft 5 is raised, the pressure inside the bellows-like cover 19 is not so low as compared with the conventional case. As a result, it is possible to effectively prevent the bellows-shaped cover 19 from being deformed abnormally when the internal pressure of the bellows-shaped cover 19 is reduced.

  Of course, at the time of contraction in which the internal pressure of the bellows-shaped cover 19 increases, the pressure in the bellows-shaped cover 19 may become higher than the atmospheric pressure (positive pressure), but this pressure is also higher than the atmospheric pressure. However, the pressure difference from the atmospheric pressure is smaller than the pressure difference when the bellows-shaped cover 19 is extended, so that the bellows-shaped cover 19 is not abnormally deformed. Even if the pressure in the bellows-shaped cover 19 becomes positive, the positive pressure time is short, and if there is a gap between the bellows-shaped cover 19, the mounting cylinder portions 19 a and 19 b are ignored. However, it is considered that there is no air leakage from the bellows-shaped cover 19 to the outside because it is fine enough.

Further, in this embodiment, since the gap between the balls 22c existing between the outer race 22b and the inner race 22a of the ball bearing 22 is used as the outer communication path 29 of the intake path 28, the intake path 28 is formed. In addition, it is not necessary to form a passage in the linear motion shaft 5 separately, and cost increase can be suppressed.
Further, since the gap between the flange 27 of the linear motion shaft 5 and the ball bearing 22 is the inner communication passage 31, similarly, it is not necessary to separately form a passage in the linear motion shaft 5.
Further, since the ball bearing 22 is covered with the flange 27, dust can be prevented from entering the ball bearing 22, particularly on the lower bellows-shaped cover 20 side.

The present invention is not limited to the embodiment described above and shown in the drawings, and can be expanded or changed as follows.
The reciprocating direction of the linear motion shaft 5 is not limited to the vertical direction.
The narrow inner communication path 31 may not be provided. In this case, the air in the vicinity of the outer communication passage 29 is sucked by the suction passage 32. However, since the pressure in the vicinity of the outer communication passage 29 is reduced by the air suction, the second arm is reduced by that amount. The negative pressure within 4 can be set high.
The chamber 30 may not be provided.
The linear movement shaft 5 is not limited to the configuration in which both sides in the axial direction are covered with the bellows-like covers 19 and 20, and one end side is accommodated in a long cylinder attached to the second arm 4 and moved up and down in the cylinder. In this way, only the remaining one end side (mostly the attachment side of the tool) covered with the bellows-like cover may be covered with the bellows-like cover.

The expanded longitudinal cross-sectional view of the principal part which shows one Embodiment of this invention Vertical side view of the second arm Side view of a clean robot consisting of a horizontal articulated robot Graph showing pressure change in each part

Explanation of symbols

  In the drawing, 4 is a second arm, 5 is a linear motion shaft, 17 and 18 are openings, 19 and 20 are bellows-like covers, 21 is an intake device, 22 is a ball bearing, 27 is a flange, 28 is an intake passage, 29 Is an outer communication path, 30 is a chamber, 31 is an inner communication path, 32 is a suction path, and 35 is a connection path.

Claims (2)

A linear motion shaft that is provided on the arm so as to be linearly reciprocable and has at least one end projecting outwardly from an opening provided in the arm, and the opening of the arm and the arm of the linear motion shaft. And a bellows-like cover that covers the protruding portion of the linear motion shaft from the arm and expands and contracts as the linear motion shaft reciprocates, and creates a negative pressure inside the arm. Thus, a clean robot that sucks outside air into the bellows-like cover through an air intake passage provided on the projecting end portion side of the linear motion shaft to prevent dust from being released into the atmosphere. In
The linear motion shaft is rotatable, one end side of the bellows-shaped cover is connected to the linear motion shaft via a ball bearing, and a gap between the inner race and the outer race of the ball bearing is at least in the intake passage. Part of
The linear motion shaft is provided with a flange that is located inside the bellows-like cover and faces the ball bearing, and a gap between the inner race and the outer race of the ball bearing is provided outside the intake passage. An outer communication path that communicates with the flange, and a gap between the ball bearing and the flange constitutes an inner communication path that communicates with the inside of the bellows-shaped cover in the intake path. robot. The flange is formed with a chamber positioned between the outer communication path and the inner communication path of the intake path, and the suction path of the linear movement shaft is configured to suck air in the chamber,
The clean robot according to claim 1, wherein a passage area of the inner communication passage of the intake passage is set to be smaller than a passage area of the chamber so that the inside of the chamber is always kept at a negative pressure.

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