Transportation apparatus and tension adjustment method of belt in the same

The present invention relates to a transportation apparatus in which first and second linkages are coupled to each other to linearly transport an object such as a wafer, and a tension adjustment method of a belt in the transportation apparatus.

For example, there is a known transportation apparatus in Patent Document 1. The transportation apparatus for linearly transporting the object includes a first linkage in which base ends of a pair of first links which have the same length with each other are pivotably coupled to a fixed table through a pair of first coupling shafts, and tip ends of the pair of first links are pivotably coupled to a pair of intermediate shafts which are fixed to a pair of intermediate tables; a second linkage in which base ends of a pair of second links which have the same length with the first links are pivotably coupled to the pair of intermediate shafts, and tip ends of the pair of first links are pivotably coupled to an object installation table through a pair of second coupling shafts; a transmission unit provided in the intermediate table and operable to transmit torque between the first and second links constituting the first and second linkages in both forward and backward directions; and a driving unit provided in the fixed table and operable to drive one of the pair of first links constituting the first linkage to rotate. In the transmission unit, one pulley of a pair of pulleys rotatably supported at the outside of the pair of intermediate shafts is integrally coupled to one of the pair of first links constituting the first linkage, and the other pulley is integrally coupled to one of the pair of second links constituting the second linkage. At this time, the upper and lower belts are partially wound around the pulleys in opposite directions with each other and both ends of the belts are fixed to the pulleys so as to transmit the torque between the pair of pulleys in both forward and backward directions. When the driving unit drives one of the first links of the first linkage to rotate in the forward and backward directions, a driving force is transmitted between a predetermined first and second links constituting the first and second linkages in the transmission unit part. Accordingly, the object installation table disposed at one end of the bottom side of an isosceles triangle formed by the first and second linkages is moved in a straight line shape in the forward and backward directions. In this way, the transportation apparatus linearly transports an object such as a wafer.

At this time, since the transmission unit has a configuration in which the upper and lower belts are partially wound around the pulleys in opposite directions with each other and both ends of the belts are fixed to the pulleys so as to transmit the torque between the pair of pulleys in both forward and backward directions, when the pulleys are allowed to rotate in a predetermined direction to apply tension to one belt in the state where the belts are partially suspended and attached to the pulleys by applying tension thereto, the other belt is loosened so that tension thereof becomes small. As a result, a problem arises in that the tension adjustment of the pair of belts is difficult. Additionally, when tensions of the pair of belts are not appropriate, acceleration abruptly acts on the transported object supported on the object installation table and the transported object deviates from a predetermined position. As a result, a problem arises in that a movement placement of the object is difficult in the subsequent process.

Patent Document 1: Japanese Patent Publication No. 4-331090A

An object of the invention is to facilitate tension adjustment of the pair of belts constituting the transmission unit provided in a coupling portion of the first and second linkages in the transportation apparatus with the above-described configuration for linearly transporting the object.

In order to achieve the above described object, according to an aspect of the present invention, there is provided a transportation apparatus operable to linearly transport an object, comprising: a first linkage, in which base ends of a pair of first links which have the same length with each other are pivotably coupled to a fixed table through a pair of first coupling shafts, and tip ends of the first links are pivotably coupled to a pair of first intermediate shafts which are fixed to a first intermediate table; a second linkage, in which base ends of a pair of second links which have the same length with the first links are pivotably coupled to the first intermediate shafts, and tip ends of the second links are pivotably coupled to a first installation table of the object through a pair of second coupling shafts; a first driving unit operable to apply torque to one of the first coupling shafts to rotate one of the first links; and a first transmission unit provided in the first intermediate table and operable to transmit the torque from the one of the first links to one of the second links, wherein the transmission unit includes: a pair of pulleys pivotably supported by the first intermediate shafts and fixed to the one of the first links and the one of the second links; and an upper belt and lower belt are partially wound around the pulleys in opposite directions with each other and fixed to the pulleys so as to transmit the torque; wherein one of the pulleys is divided into an upper part fixed with the upper belt and a lower part fixed with the lower belt in an axial direction of the first intermediate shafts.

According to the above-described configuration, one of the pair of pulleys is divided into two parts in the axial direction, and one ends of the pair of belts can be fixed to the divided pulleys, respectively. Accordingly, when the divided pulleys rotate in an opposite direction with each other in the state where the other ends of the pair of belts which are wound in an opposite direction with each other are fixed to deviated positions of a fixed rotation member in the axial direction, respectively, and one ends of the pair of belts are fixed to the divided pulleys, respectively, predetermined tensions are applied to the belts. In this state, one ends of the pair of links are fixed to the divided pulleys. Likewise, since the pulley to which one ends of the pair of belts are fixed is divided into two parts in the axial direction, the tension adjustment of the pair of belts can be individually carried out, thereby facilitating the tension adjustment.

The transportation apparatus may further comprise: a third linkage, in which base ends of a pair of third links which have the same length with each other are pivotably coupled to the fixed table through a pair of third coupling shafts, and tip ends of the third links are pivotably coupled to a pair of second intermediate shafts which are fixed to a second intermediate table;

a fourth linkage, in which base ends of a pair of fourth links which have the same length with the third links are pivotably coupled to the second intermediate shafts, and tip ends of the fourth links are pivotably coupled to a second installation table of the object through a pair of second coupling shafts; a second driving unit operable to apply torque to one of the third coupling shafts to rotate one of the third links; and a second transmission unit provided in the second intermediate table and operable to transmit the torque from the one of the third links to one of the fourth links, wherein the first installation table may be formed so as not to have a conflict with the second installation table while transporting the object.

According to the above-described configuration, since two linear transportation units are simultaneously operated in different operation spaces without conflicting with each other, thereby realizing a severalfold increase in the transportation capability of the object.

A first attachment portion for attaching a tension applying member may be formed on the upper part of the divided pulley and a second attachment portion for attaching a tension applying member may be formed on the lower part of the divided pulley.

According to the above-described configuration, when the tension applying bar is inserted into the insertion holes of the divided pulleys, torque is easily applied to the divided pulleys, thereby facilitating the tension adjustment of the belts.

According to another aspect of the present invention, there is provided a method for adjusting tensions of the upper and lower belts of the transmission unit, comprising: attaching a tension applying member to the first attachment portion; attaching another tension applying member to the second attachment portion; and connecting the tension applying members by a spring, thereby adjusting the tensions of the upper and lower belts.

According to the above-described configuration, since the tensions of the belts become large in proportion to the strength of the spring connecting the tension applying members to each other, the tensions of the belts can be adjusted and the tensions of the belts can be set to be identical with each other by selecting a spring having a different spring constant. Additionally, since the rotation motions acting on the other pulleys are offset by the tensions of the pair of belts, it is not necessary to retard the rotation motions of the other pulleys. Likewise, since the divided pulleys are stopped in the state where the tensions of the pair of belts are adjusted, it is possible to easily fix one ends of the pair of links to the divided pulleys in the state where the tension applying members are connected to each other by the spring.

According to the invention, since one of the pair of pulleys is divided into two parts in the axial direction, the tension adjustment of the pair of belts, that is, the belts which are partially wound around the pair of pulleys in an opposite direction with each other and of which both ends are fixed to the pulleys can be individually carried out, thereby facilitating the tension adjustment.

FIG. 1 is an overall perspective view illustrating a transportation apparatus according to an embodiment in the state where a first linkage LD 1 overlaps with a second linkage LD 2 when viewed from the top.

FIG. 2 is a side view illustrating the transportation apparatus in the state where the first linkage LD 1 overlaps with the second linkage LD 2 when viewed from the top.

FIG. 3 is a schematic top view illustrating a linear transportation unit U 1 according to the embodiment of the invention.

FIG. 4 is a sectional view taken along the line X 1 -X 1 shown in FIG. 3 .

FIG. 5 is a sectional view taken along the line X 2 -X 2 shown in FIG. 3 .

FIG. 6 is a sectional view taken along the line X 3 -X 3 shown in FIG. 3 .

FIG. 7 is a sectional view taken along the line Y 1 -Y 1 shown in FIG. 6 .

FIG. 8 is a sectional view taken along the line Y 2 -Y 2 shown in FIG. 6 .

FIG. 9 is an exploded perspective view illustrating an intermediate table E according to the embodiment of the invention.

FIG. 10 is a schematic view illustrating a method for adjusting tensions of a first belt V 1 and a second belt V 2 by use of a tension spring 17 .

FIG. 11 is a perspective view illustrating a state where the linear transportation unit U 1 is being operated.

FIG. 12 is a top view illustrating a state where the linear transportation unit U 1 is operated.

FIG. 13 is a schematic view illustrating a state where an object is transported by the linear transportation unit U 1 .

Hereinafter, an exemplary embodiment of the invention will be described in detail. First, an overall configuration of a transportation apparatus for linearly transporting an object will be simply described with reference to FIGS. 1 to 9 . Then, parts related to the invention will be described in detail. As shown in FIGS. 1 and 2 , the transportation apparatus according to the embodiment includes two linear transportation units U 1 and U 2 having the same basic configuration with each other. Each of the linear transportation units U 1 and U 2 is configured to linearly transport a wafer (object) W in an arrow direction Q by a link motion. At this time, in each of link operation spaces J 1 and J 2 at both sides of a fixed table A, first links L 1 a and L 1 b do not interfere with second links L 2 a and L 2 b . Also, the transported wafers (object) W do not interfere with each other. Accordingly, in the description hereinafter, only one linear transportation unit U 1 will be described, while only different points of the other linear transportation unit U 2 which are different from the one linear transportation unit U 1 will be described.

The linear transportation unit U 1 is configured such that a first linkage LD 1 and a second linkage LD 2 are coupled to each other through a transmission unit D. The first linkage LD 1 is configured such that base ends of a pair of first links L 1 a and L 1 b having the same length with each other are pivotably coupled to the fixed table A through a pair of first coupling shafts S 1 a and S 1 b , respectively, and the tip ends of the pair of first links L 1 a and L 1 b are pivotably coupled to a pair of intermediate shafts S 3 a and S 3 b of an intermediate table E, respectively. The first coupling shaft S 1 a also serves as a drive shaft S 0 , and the drive shaft S 0 (first coupling shaft S 1 a ) is rotatably supported by the fixed table A through a bearing B 1 . At this time, the drive shaft S 0 (first coupling shaft S 1 a ) and the first link L 1 a are integrally coupled to each other by a chock 1 , a chock receiving portion 2 , and bolts T 1 (see FIG. 4 ). The first coupling shaft S 1 b is fixed to the fixed table A through bolts T 2 , and the base end of the first link L 1 b is pivotably coupled to the first coupling shaft S 1 b through a pair of bearings B 2 (see FIG. 5 ). Additionally, the second linkage LD 2 is configured such that base ends of a pair of second links L 2 a and L 2 b having the same length with each other are pivotably coupled to the pair of intermediate shafts S 3 a and S 3 b , respectively, and the tip ends of the pair of the second links L 2 a and L 2 b are pivotably coupled to a pair of second coupling shafts S 2 a and S 2 b fixed to the bottom surface of a tip-end link plate 3 through a pair of upper and lower bearings B 3 and B 4 , respectively (see FIGS. 4 and 5 ). A wafer installation table M 1 is provided on the top surface of the tip-end link plate 3 . Additionally, each length of the first links L 1 a and L 1 b and the second links L 2 a and L 2 b is denoted by K 1 .

When the first linkage LD 1 performs a parallel link motion in the link operation space J 1 by the torque of the first coupling shaft S 1 a serving as the drive shaft S 0 , the pair of first links L 1 a and L 1 b pivot about the intermediate shafts S 3 a and S 3 b with respect to the intermediate table E. The transmission unit D attached to the intermediate table E operates the second linkage LD 2 by using a rotation of the pair of first links L 1 a and L 1 b . As shown in FIGS. 6 and 9 , the transmission unit D is attached to the intermediate table E in the manner that the pair of upper and lower intermediate link plates 5 are coupled to each other through the pair of left and right intermediate shafts S 3 a and S 3 b and bolts T 3 . Gaps K 2 of the pair of left and right intermediate shafts S 3 a and S 3 b , the pair of first coupling shafts S 1 a and S 1 b , and the pair of second coupling shafts S 2 a and S 2 b are the same as one another. The pair of first links L 1 a and L 1 b constituting the first linkage LD 1 are pivotably supported by the bottom portions of the intermediate shafts S 3 a and S 3 b of the intermediate table E, respectively.

That is, the first link L 1 b of the first linkage LD 1 is directly and pivotably coupled to the bottom portion of the intermediate shaft S 3 b through a pair of upper and lower bearings B 5 . The first link L 1 a is disposed below a first pulley P 1 which is rotatably supported by the intermediate shaft S 3 a through a pair of upper and lower bearings B 6 , and is integrally coupled to the first pulley P 1 through a plurality of bolts T 4 so as to be pivotably supported by the intermediate shaft S 3 a . In the same manner, the second link L 2 a of the second linkage LD 2 is directly and pivotably coupled to the top portion of the intermediate shaft S 3 a through a pair of upper and lower bearings B 7 . The second link L 2 b is disposed above a second pulley P 2 which is rotatably supported by the intermediate shaft S 3 b through a pair of upper and lower bearings B 8 , and is integrally coupled to the second pulley P 2 through a plurality of bolts T 5 so as to be pivotably supported by the intermediate shaft S 3 b.

The first and second pulleys P 1 and P 2 are of a cylindrical shape, but it is different in that the second pulley P 2 is formed in a single body and the first pulley P 1 is divided into two parts in an axial direction. The second pulley P 2 is integrally coupled to the base end of the second link L 2 b of the second linkage LD 2 through a plurality of bolts T 5 , but the first pulley P 1 having two parts is configured such that the long bolts T 4 , which are rotated by a bolt rotating tool 7 inserted through a tool insertion through-hole 6 formed in the lower intermediate link plate 5 of the intermediate table E, integrally connects the pulleys P 1 a and P 1 b to the tip end of the first link L 1 a of the first linkage LD 1 .

Additionally, as shown in FIGS. 6 to 8 , first and second belts V 1 and V 2 are partially wound around the pulleys P 1 a and P 1 b constituting the first pulley P 1 and the second pulley P 2 so that the winding angles are substantially at 180° and the winding directions are opposite to each other. Both ends of the belts V 1 and V 2 are fixed to flat portions 8 of the divided pulleys P 1 a and P 1 b of the first pulley P 1 and the second pulley P 2 through a plurality of bolts T 6 .

Accordingly, when the first coupling shaft S 1 a serving as the drive shaft S 0 is driven to rotate so that an intersection angle between the first links L 1 a and L 1 b of the first linkage LD 1 and the second links L 2 a and L 2 b of the second linkage LD 2 becomes small, as shown in FIG. 7 , a torque of the first links L 1 a and L 1 b is transmitted to the second links L 2 a and L 2 b by the upper second belt V 2 . At this time, since the first links L 1 a and L 1 b rotate in the counterclockwise direction with respect to the intermediate table E when viewed from the top, the second links L 2 a and L 2 b rotate in the clockwise direction with respect to the intermediate table E when viewed from the top. Conversely, when the intersection angle between the first links L 1 a and L 1 b of the first linkage LD 1 and the second links L 2 a and L 2 b of the second linkage LD 2 becomes large, as shown in FIG. 8 , the torque of the first links L 1 a and L 1 b is transmitted to the second links L 2 a and L 2 b by the lower first belt V 1 .

Additionally, since the length of the pair of first links L 1 a and L 1 b is the same as that of the pair of second link L 2 a and L 2 b , as shown in FIGS. 11 to 13 , the pair of first links L 1 a and L 1 b are disposed on the right side of the pair of second links L 2 a and L 2 b . Further, when the first coupling shaft S 1 a serving as the drive shaft S 0 rotates in the clockwise direction when viewed from the top in the state where the intersection angle between the pair of first links L 1 a and L 1 b and the pair of second links L 2 a and L 2 b is maximum, a wafer installation table M 1 that is normally positioned at one end of the bottom side of an isosceles triangle linearly moves from the left side to the right side so as to linearly transport the wafer W. Additionally, after the movement placement of the wafer W ends, it is possible to return the wafer installation table M 1 to a wafer extracting position by rotating the first coupling shaft S 1 a serving as the drive shaft S 0 in the counterclockwise direction when viewed from the top so that the pair of first links L 1 a and L 1 b and the pair of second links L 2 a and L 2 b move in a manner opposite to that upon transporting the wafer.

In this way, the driving force of the second linkage LD 2 is dependent on the driving force that is transmitted from the first linkage LD 1 through the transmission unit D attached to the intermediate table E when the link motion of the first and second linkages LD 1 and LD 2 constituting the linear transportation unit U 1 is carried out. For this reason, when the tensions of the first and second belts V 1 and V 2 constituting the transmission unit D are too large, it is difficult to smoothly perform the power transmission. In the worst case, malfunctions of the first and second linkages LD 1 and LD 2 occur. Conversely, when the tensions thereof are too small, “large slacks” of the first and second belts V 1 and V 2 occur. For this reason, the belts start to abruptly operate after a short-time non-operation state at the time of operating the belts which are in the stop state. At this time, a large force acts on the wafer W which is a transported object, and thus the wafer W moves slightly with respect to the wafer installation table M 1 . As a result, a problem arises in that the movement placement of the wafer W cannot be smoothly carried out or the movement placement thereof is not possible. Accordingly, it is necessary to appropriately set the tensions of the first and second belts V 1 and V 2 .

As shown in FIGS. 6 and 9 , the first pulley P 1 includes the pair of upper and lower divided pulleys P 1 a and P 1 b which are divided into two parts in the axial direction. One (upper) divided pulley P 1 b is provided with a plurality of female screws 11 which are arranged in the circumferential direction with a predetermined gap interposed therebetween. The other (lower) divided pulley P 1 a is provided with a plurality of insertion through-holes 12 with a long hole shape which are formed in each corresponding position of the female screws 11 of the divided pulley P 1 a . Additionally, as shown in FIGS. 7 and 8 , since the first and second belts V 1 and V 2 are not wound based on the flat portions 8 of the divided pulleys P 1 a and P 1 b , insertion through-holes 14 a and 14 b for a tension applying bar, through which the tip ends of the tension applying bars 13 are inserted, are formed at opposite positions in the radius direction.

The first and second upper and lower pulleys P 1 a and P 1 b are temporarily coupled to the first link L 1 a by the bolts T 4 which are inserted through a plurality of bolt insertion through-holes 15 (see FIG. 9 ) with a long hole shape formed in the tip end of the first link L 1 a in the circumferential direction so that the divided pulleys P 1 a and P 1 b are rotatable with the first link L 1 a . In this state, as depicted by the chain double-dashed line shown in FIG. 7 , the tension of the second belt V 2 is set in the manner that the tension applying bar 13 is inserted through the insertion through-hole 14 b for the tension applying bar of the upper divided pulley P 1 b to apply torque so that the divided pulley P 1 b rotates in the counterclockwise direction when viewed from the top. Also, as depicted by the chain double-dashed line shown in FIG. 8 , the tension of the first belt V 1 is set in the manner that the tension applying bar 13 is inserted through the insertion through-hole 14 a for the tension applying bar of the lower divided pulley P 1 a to apply torque so that the divided pulley P 1 a rotates in the clockwise direction when viewed from the top. Subsequently, when the bolts T 4 are fastened by the bolt rotating tool 7 which is inserted through the tool insertion through-hole 6 formed in the intermediate link plate 5 of the intermediate table E, the divided pulleys P 1 a and P 1 b are integrally coupled to the first link L 1 a , thereby setting the tensions of the first and second belts V 1 and V 2 .

As described above, the reason why the tensions of the belts V 1 and V 2 can be adjusted in the aforementioned manner is because the insertion through-holes 15 which are formed in the tip end of the first link L 1 a and the insertion through-holes 12 which are formed in the divided pulley P 1 a in the axial direction are formed in a long hole shape in the circumferential direction so that the fixed positions of the divided pulleys P 1 a and P 1 b with respect to the first link L 1 a can be finely adjusted in the circumferential direction. Additionally, it is necessary to fix the second pulley P 2 so as not to be pivotable upon adjusting the tensions of the belts V 1 and V 2 . Accordingly, the second links L 2 a and L 2 b may be fixed so as not to be pivotable, or a bar member (not shown) may be inserted into one of a pair of fixed holes 16 a and 16 b which are formed in deviated positions in the radius direction along the circumferential direction of the second pulley P 2 so as to fix the bar member thereto.

Additionally, as shown in FIG. 10 , it is possible to adjust the tensions of the first and second belts V 1 and V 2 in the manner that a tension spring 17 is wound around the pulley P 2 of the other second pulley P 2 and then both ends of the tension spring 17 are suspended on the tip ends of the tension applying bar 13 in the state where the tension applying bars 13 are inserted through the insertion through-holes 14 a and 14 b for the tension applying bar of the divided pulleys P 1 a and P 1 b . In this manner, when the tensions of the belts V 1 and V 2 are adjusted by the tension spring 17 , the tensions of the belts V 1 and V 2 are precisely set by a strength (spring constant) of the tension spring 17 , and the tensions of the belts V 1 and V 2 are identical with each other. Also, the torque acting on the second pulley P 2 is offset. Accordingly, it is advantageous in that the second pulley P 2 does not rotate without retarding the rotation thereof. Additionally, it is desirable to configure the tension spring 17 such that a spring portion 17 a constitutes a linear arrangement part and a non-spring portion 17 b constitutes a part partially winding around the second pulley P 2 .

The transportation apparatus according to the embodiment includes two linear transportation units U 1 and U 2 having the wafer installation tables M 1 and M 2 which are different from each other. That is, as shown in FIGS. 1 and 2 , the wafer installation table M 2 of the linear transportation unit U 2 is formed in a long U shape when viewed from the side. In the state where the linear transportation units U 1 and U 2 are positioned in a straight line shape, a part of the wafer installation table M 1 of the other linear transportation unit U 1 and the wafer W placed on the wafer installation table M 1 can be received inside the wafer installation table M 2 . With such a configuration, the linear transportation units U 1 and U 2 operate in different link operation spaces J 1 and J 2 , respectively, and thus even in the center of the transportation course of the wafer W, the wafer installation tables M 1 and M 2 and the wafers W placed on the wafer installation tables M 1 and M 2 do not conflict with each other, respectively. Accordingly, two linear transportation units U 1 and U 2 can be simultaneously operated in the different link operation spaces J 1 and J 2 , thereby realizing a severalfold increase in the transportation capability of the wafer W.

Further, one of the pair of pulleys P 1 and P 2 may be configured to be divided into two parts in the axial direction, and thus it is possible to configure the second pulley P 2 to be divided into two parts.