WORK CARRIER

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a work carrier that carries a plate-shaped work, for example in a vacuum space.

2. Description of the Related Art

An example of carrying apparatuses that carry a plate-shaped work in a vacuum space so far developed is disclosed in JP-A-No. 2007-118171. The work carrier according to this document includes a fixed base, a pivotal base retained by the fixed base pivotally with respect thereto, a lift base to which the pivotal base is mounted, a ball screw slide mechanism that vertically moves the lifting base, a link arm mechanism supported by the pivotal base to be swingable with respect thereto, and a hand supported by the link arm mechanism.

The hand and the link arm mechanism are located in the vacuum space, while the fixed base is located in the atmospheric space. The upper wall of a casing of the fixed base separates the upper vacuum space from the lower atmospheric space. The fixed base contains therein motors for rotating the pivotal base and for driving the link arm mechanism, the ball screw slide mechanism, and a motor for driving the ball screw slide mechanism.

In the work carrier thus constructed, a work, which is heated to a high-temperature, may affect the peripheral components by radiant heat. In light of this, the link arm mechanism, which is most likely to be exposed to the radiant heat, is provided with a coolant circuit for cooling the peripheral components, that is arranged to extend from inside the fixed base and through the pivotal base. In the vicinity of a guide rail of the link arm mechanism, an annular pipe is provided in communication with the coolant circuit.

In the foregoing conventional work carrier, however, the coolant circulating pipe has a circular cross section, and hence the contact area of the pipe with respect to the frame member of the link arm mechanism tends to be unduly small. Unfavorably, such a structure may impede efficient heat dissipation from the frame member exposed to the radiant heat.

SUMMARY OF THE INVENTION

The present invention has been proposed under the foregoing situation. It is therefore an object of the present invention to provide a work carrier configured to efficiently dissipate heat from a member liable to be exposed to radiant heat.

To attain the foregoing object, the present invention adopts the following technical measures.

According to an embodiment of the present invention, there is provided a work carrier comprising: a work carrying mechanism; a cooling pipe for cooling the work carrying mechanism by circulation of a coolant; a thermally-conductive elastic member held in contact with the work carrying mechanism and the cooling pipe; and a fixing element for fixing the cooling pipe to the work carrying mechanism.

Preferably, the elastic member extends in a longitudinal direction of the cooling pipe.

Preferably, the elastic member is bent in a cross section perpendicular to a longitudinal direction of the cooling pipe prior to fixation.

Preferably, the elastic member is made of a deformable metal.

Preferably, the elastic member is made of aluminum.

Preferably, the cooling pipe includes a flat surface held in contact with the elastic member.

Preferably, the work carrier of the present invention further comprises: a scissors lift mechanism for vertically lifting and lowering the work carrying mechanism; a base seat on which the scissors lift mechanism is mounted; and a rotation mechanism for rotating the base seat about a vertical axis.

Preferably, the scissors lift mechanism comprises: a stage on which the work carrying mechanism is mounted; a first scissors link including a first arm and a second arm; a second scissors link arranged parallel to the first scissors link and including a third arm and a fourth arm; and a lifting driver mounted on the base seat. The first arm and the second arm are connected to each other at central portions of the respective arms so as to be rotatable to each other. The first arm includes an upper end portion rotatably connected to the stage, and a lower end portion horizontally movable near the base seat. The second arm includes a lower end portion rotatably connected to the base seat, and an upper end portion horizontally movable near the stage. The third arm and the fourth arm are connected to each other at central portions of the respective arms so as to be rotatable to each other. The third arm includes an upper end portion rotatably connected to the stage, and a lower end portion horizontally movable near the base seat. The fourth arm includes a lower end portion rotatably connected to the stage, and an upper end portion horizontally movable near the stage. The lifting driver is configured to move the lower end portions of the first arm and the third arm near the base seat.

Preferably, the work carrier of the present invention further comprises: a lower pipe extending from the lower end portion of the second arm to the central portion of the second arm; an upper pipe extending from the upper end portion of the third arm to the central portion of the third arm; and an intermediate pipe extending between the central portion of the second arm and the central portion of the third arm and connected to the lower pipe and the upper pipe.

Preferably, the work carrier of the present invention further comprises: a through pipe extending from the base seat, via the lower end portion of the second arm and connected to the lower pipe; and a connection pipe connecting between the upper pipe and the work carrying mechanism.

Preferably, the through pipe, the lower pipe, the intermediate pipe, the upper pipe and the connection pipe are configured to provide a pipeline in which a coolant supply pipe and a coolant discharge pipe, both connected to the cooling pipe, are accommodated.

In accordance with the above arrangement, the work carrying mechanism, liable to be exposed to radiant heat, is provided with a cooling pipe which is pressure fixed to the work carrying mechanism, with an elastic member disposed between the pipe and the work carrying mechanism. In this manner, the cooling pipe is held in contact with the work carrying mechanism via the elastic member. Thus, the cooling pipe is to have an advantageously large contact area and therefore capable of effectively drawing heat from the elements of the work carrying mechanism exposed to radiant heat.

Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view showing a work carrier according to an embodiment of the present invention;

FIG. 2 is a side view showing main portions of the work carrier shown in FIG. 1;

FIG. 3 is a front view showing main portions of the work carrier shown in FIG. 1;

FIG. 4 is a perspective view showing a work carrying mechanism provided in the work carrier shown in FIG. 1;

FIG. 5 is a partially cut away plan view of the work carrying mechanism shown in FIG. 4; and

FIGS. 6A and 6B are cross-sectional views showing the fixing structure of a cooling pipe provided in the work carrying mechanism shown in FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

FIGS. 1 to 6B depict a work carrier according to an embodiment of the present invention. The work carrier A is intended for carrying a thin plate-shaped work such as an LCD panel. The work carrier A includes a base unit 1 that accommodates a rotation mechanism (not shown), a base seat 2, a scissors lift mechanism 4, an upper pipe 5, an intermediate pipe 6, a lower pipe 7, and a work carrying mechanism 8. The base unit 1 is located in the atmospheric space below the floor level, while the base seat 2, the scissors lift mechanism 4, the upper pipe 5, the intermediate pipe 6, the lower pipe 7, and the work carrying mechanism 8 are located, for example, in a vacuum space inside a non-illustrated chamber. By the work carrier A, a work heated for example up to approximately 200° C. is carried in the vacuum space. For better understanding, FIG. 1 illustrates the scissors lift mechanism 4 and the work carrying mechanism 8 in a separated state. The inside of the chamber does not have to be a completely vacuum space, but may be a space depressurized to a certain extent, or pressurized to a certain extent. The inside of the chamber may be loaded with a substance other than air (for instance, nitrogen).

The base unit 1 accommodates therein a rotation mechanism that rotates the base seat 2 about a vertical axis. The rotation mechanism is constituted of a planet gear mechanism, including e.g. a driving motor for attaining required rotational movement. The rotation mechanism includes a rotating shaft 10 of a hollow structure, connected to a lower face of the base seat 2 via a sealed bearing 11 (See FIG. 1). The rotation of the rotating shaft 10 causes the base seat 2 to rotate about the vertical axis. The inside of the base unit 1 is maintained at the atmospheric pressure. The base unit 1 accommodates only the rotation mechanism for rotating the base seat 2 about the vertical axis, but not the motors for rotating a pivotal base or for driving a link arm mechanism, a ball screw slide mechanism, and a motor for driving the ball screw slide mechanism. Accordingly, the overall structure, in particular the height, can be more compact than is conventionally possible. Since the base unit 1 can be significantly smaller in height than a conventional one, the base unit 1 can be accommodated in an advantageously shallow underfloor space.

The base seat 2 serves to sustain the scissors lift mechanism 4. On the upper face of the base seat 2, a through pipe 3 is provided. An end portion of the through pipe 3 is led into the base unit 1 through the hollow portion of the rotating shaft 10. The other end portion of the through pipe 3 is connected to the lower pipe 7 through a lower relay pipe 30 (See FIG. 2). Other constituents provided on the base seat 2 will be described later.

The scissors lift mechanism 4 serves to sustain the work carrying mechanism 8, and to vertically reciprocate the work carrying mechanism 8 as a whole. The scissors lift mechanism 4 includes a stage 40 on which the work carrying mechanism 8 is mounted, a first and a second scissors link 41, 42, and a lift driving motor 43. The first scissors link 41 includes a first and a second arms 410, 411, and the second scissors link 42 also includes a third and a fourth arms 420, 421 of the same shape and size as those of the first and second arms. The first and the second scissors link 41, 42 are disposed parallel to each other on the respective sides of the stage 40, with a spacing therebetween.

On a rear end portion of the upper face of the base seat 2, a pair of brackets 21 and a pair of bearings (not shown) are provided so as to connect a respective lower end portion of the arms 411, 421 rotatably about a horizontal axis. Between the two brackets 21, an air-tightly sealed motor box 22 that accommodates therein the lift driving motor 43 is provided. On a front end portion of the upper face of the base seat 2, a pair of ball screw shafts 23, and a nut block 24, as well as a pair of slide rails 25 and a pair of linear blocks 26 are provided so as to connect a respective lower end portion of the arms 410, 420 horizontally slidably back and forth. The ball screw shaft 23 is made to rotate by the lift driving motor 43, so that the nut block 24 thread-engaged with the ball screw shaft 23 is made to slide back and forth. To the end portions of the nut block 24, the lower end portion of the arms 410, 420 are rotatably connected respectively. The respective lower end portions of the arms 410, 420 are supported by the slide rail 25 via the linear block 26.

As shown in FIG. 3, the through pipe 3 is once introduced into the air-tightly sealed motor box 22, and communicatively connected to the lower relay pipe 30 sticking outward from inside the motor box 22. A swivel joint J1 is provided so as to penetrate through the lower end portion of the arm 411 and the bracket 21, and the lower relay pipe 30 is communicatively connected to the lower end portion of the lower pipe 7 via the swivel joint J1. Here, FIG. 3 is a front view of the scissors lift mechanism 4 from a position slightly ahead of the intermediate pipe 6, and hence the arms 410, 411, 420, 421 are partially cut away.

The upper pipe 5 is disposed from an upper end portion to a central portion of the arm 420, along an outer face of the arm 420. The intermediate pipe 6 is located so as to connect the central portion of the arms 410, 411 and that of the arms 420, 421. The lower pipe 7 is disposed, as shown in FIG. 3, from the central portion to the lower end portion of the arm 411, along an outer face of the arm 411. An L-shaped joint J2 is disposed so as to penetrate through the middle portion where the arms 410, 411 intersect with each other, and the upper end portion of the lower pipe 7 is communicatively connected to an end portion of the intermediate pipe 6 via the L-shaped joint J2. The other end portion of the intermediate pipe 6 is communicatively connected to the lower end portion of the upper pipe 5, via a swivel joint J3 disposed so as to penetrate through the central portion where the arms 420, 421 intersect with each other.

On the upper face of the stage 40, the work carrying mechanism 8 is fixed. On a rear end portion of the lower face of the stage 40, a pair of brackets 40A and a pair of bearings (not shown) are provided so as to connect the respective upper end portion of the arms 410, 420, rotatably about a horizontal axis. On a front end portion of the lower face of the stage 40, a pair of slide rails 40B and a pair of linear guides 40C are provided so as to connect the respective upper end portion of the arms 411, 421, horizontally slidably back and forth. On a region from the rear end portion to a central portion of the lower face of the stage 40, connection pipes 40E, 40F, 40G and a through connection pipe 40H are provided. An end portion of the connection pipe 40E is communicatively connected to the upper end portion of the upper pipe 5 via a swivel joint J4 disposed so as to penetrate through the upper end portion of the arm 420 and the bracket 40A. The other end portion of the connection pipe 40E is communicatively connected to an end portion of the connection pipe 40F via an L-shaped joint J5 disposed so as to penetrate through the upper end portion of the arm 410 and the bracket 40A. The other end portion of the connection pipe 40F is communicatively connected to an end portion of the connection pipe 40G via an L-shaped joint J6. The other end portion of the connection pipe 40G is communicatively connected via an L-shaped joint J7 to a lower end portion of the through connection pipe 40H disposed so as to penetrate through the central portion of the stage 40. An upper end portion of the through connection pipe 40H is connected to the work carrying mechanism 8.

Thus, the through pipe 3, the lower relay pipe 30, the upper pipe 5, the intermediate pipe 6, the lower pipe 7, the connection pipes 40E, 40F, 40G, and the through connection pipe 40H constitute a pipeline that achieves communication from the inside of the base unit 1 to the work carrying mechanism 8. The pipeline is air-tightly sealed to be thereby maintained at the atmospheric pressure. The pipeline thus arranged accommodates power supply cables for the slide-driving motor of the work carrying mechanism 8 and for the lift driving motor 43, while also accommodating the coolant supply pipe and the coolant discharge pipe that serve to cool the components of the work carrying mechanism 8. Such configuration enables routing the power supply cables, the coolant supply pipe and the coolant discharge pipe from the inside of the base unit 1 to the motor box 22 and the work carrying mechanism 8, without exposing them to the vacuum space. In this embodiment, a liquid such as water is employed as the coolant from the viewpoint of thermal efficiency. Alternatively, for example dry air may be employed as the coolant.

The work carrying mechanism 8 includes a pair of hands 80 that retains the work, a belt sliding mechanism 81 (See FIGS. 4 and 5) serving to linearly reciprocate the hands 80 horizontally back and forth independently from each other, a sealed box 82 that accommodates therein a slide-driving motor that activates the belt sliding mechanism 81, a guide member 83 that retains the belt sliding mechanism 81 and the sealed box 82, and a cooling pipe 84 for coolant circulation.

As shown in FIG. 1, the guide member 83 includes a main body 83A and a cover 83B, and has a rectangular shape in plan view. As shown in FIG. 4, the main body 83A includes a first and a second guide rail 83C, 83D each constituted of a set of two rows, extending longitudinally. The first guide rail 83C movably sustains a lower end portion 80a of the upper one of the hands 80 via a slider 80b, and the second guide rail 83D movably sustains a lower end portion of the other hand 80 via a slider 80c, so as not to interfere with the upper hand 80. The first and the second guide rails 83C, 83D are covered with the cover 83B, which includes slits 80d, 80e formed at a position corresponding to each guide rail 83C, 83D, for sticking out the sliders 80b, 80c (See FIG. 1). A lower end portion 80a of the upper hand 80 is formed so as to circumvent an outer edge of the lower hand 80, so that the two hands 80 are located so as to vertically overlap defining a gap therebetween, and can therefore horizontally move back and forth without mutual interference.

Referring to FIGS. 4 and 5, the belt sliding mechanism 81 is constituted of a pair, so as to extend longitudinally. The pair of belt sliding mechanisms 81 each includes an inner and outer pair of belts 81A, 81B looped about a pulley which is not shown. To the two rows of belts 81A, 81B on the right, for example, the lower end portion 80a of the upper hand 80 is connected via the slider 80b (See FIG. 4). When the belts 81A, 81B on the right rotate, the upper hand 80 is made to horizontally move back and forth along the guide rail 83C. To the two rows of belts 81A, 81B on the left, the lower end portion of the lower hand 80 is connected via the slider 80c (See FIG. 4). When the belts 81A, 81B on the left rotate, the lower hand 80 is made to horizontally move back and forth along the guide rail 83D. Instead of two rows, a single row of belt may be provided on the left and the right respectively.

As shown in FIG. 5, the sealed box 82 is located at a generally central portion of the main body 83A. The sealed box 82 accommodates therein the slide-driving motors 82C, 82D and reduction gears 82E, 82F, serving to rotate the belts 81A, 81B. On each lateral face of the sealed box 82, driving gears 82G, 82H and tension rollers 82J that drive the belts 81A, 81B are attached, and the belts 81A, 81B are engaged about the driving gears 82G, 82H and the tension rollers 82J. The two driving gears 82G, 82H on one of the lateral faces of the box body 82A, for example, is supported via a sealed bearing (not shown) by a drive shaft (not shown) of the reduction gear 82E sticking out from the lateral face of the box body 82A, and the rotating speed and direction of the driving gears 82G, 82H are switched through controlling the slide-driving motor 82C. The two driving gears 82G, 82H located on the other side of the box body 82A are also configured as above. Thus, the two sets of belts 81A, 81B on the respective sides are independently rotated, so that the upper and the lower hands 80 are made to slide independent from each other.

The sealed box 82 includes a communication orifice (not shown) formed through the bottom portion thereof, for introducing the coolant supply pipe and the coolant discharge pipe into the sealed box 82. To the communication orifice, the through connection pipe 40H on the stage 40 is air-tightly connected. Through the through connection pipe 40H and the communication orifice thus configured, the coolant supply pipe and the coolant discharge pipe, and also the power supply cable are introduced into the sealed box 82. Inside the sealed box 82, the leading end portion of the coolant supply pipe is connected to an upstream branch socket 82K, and the leading end portion of the coolant discharge pipe is connected to a downstream branch socket 82L. To the upstream branch socket 82K, two sets of cooling pipes 84 are connected, so as to be led out through the air-tight through hole from inside the sealed box 82. These cooling pipes 84 pass around the periphery of the belt sliding mechanism 81 and return to the inside of the sealed box 82, to be connected to the downstream branch socket 82L. The cooling pipes 84 are located so as to surround the belt sliding mechanism 81 and the guide rails 83C, 83D. In other words, the cooling pipes 84 are provided such that the coolant flowing therein circulates about the belt sliding mechanism 81 and the guide rails 83C, 83D. Accordingly, the belt sliding mechanism 81 and the guide rails 83C, 83D, closely exposed to the radiant heat, exhibit efficient heat dissipation performance because of the coolant flowing through inside the cooling pipes 84.

As shown in FIG. 6A, the cooling pipe 84 is constituted of, for example, a pipe made of stainless steel and having a rectangular cross section. The frame member 830 constituting the main body 83A is of stainless steel for example. A bracket 86 and bolts 87, serving as fixing elements, are used to fix the cooling pipe 84 under pressure to the frame member 830, with the elastic member 85 interposed between the pipe 84 and the frame member 830. FIGS. 4 and 5 show a plurality of brackets, only some of which are indicated by numeral 86, with the remaining ones unnumbered.

The elastic member 85 is a metal strip in the form of a leaf spring and made of a heat-conducting material such as gold, silver, copper or aluminum. A elastic member 85 made of aluminum may be advantageous in terms of cost reduction. In a natural state, i.e. before the cooling pipe 84 is fixed, the elastic member 85 is slightly bent as viewed in a cross section perpendicular to the longitudinal direction of the cooling pipe 84. Then, with the elastic member 85 held between the frame member 830 and the cooling pipe 84, the bracket 86 is attached to the frame member 830 so that the cooling pipe 84 is fixed to the frame member 830 under the urging force of the bracket 86, and the elastic member 85 is deformed between the frame member 830 and the cooling pipe 84. As the elastic member 85 is being pressed further between the frame member 830 and the cooling pipe 84, the elastic member 85 is so deformed that the contact area with respect to the frame member 830 and the cooling pipe 84 increases. It should be noted here that though the contact surface of the elastic member 85 thus fixed is depicted as being flat in FIG. 6B, the contacting surface may be actually slightly bent.

It is possible to enjoy some cooling effect by contacting the flat surface of the cooling pipe 84 with the frame member 830 directly. However, the elastic member 85, disposed between the cooling pipe 84 and the frame member 830 ensures more proper contact between them, thereby enhancing the cooling effect. In addition, the elastic member 85 compensates thermal distortion of the cooling pipe 84 by absorbing or following the deformation, thereby preventing degradation of the cooling effect. The elastic member 85 may be made of a relatively hard material such as stainless steel, but preferably made of aluminum, which is soft enough to deform in accordance with the profile of the frame member 830 and the cooling pipe 84, thereby ensuring proper contact between the frame member 830 and the cooling pipe 84 for efficient thermal conduction. In this manner, the elastic member 85 prevents partial contact or even point contact between the frame member and the cooling pipe.

If the elastic member 85 is not used, and the cooling pipe 84 is pressed directly onto the frame member 830 by the bracket 86, the contact area between the frame member 830 and the cooling pipe 84 may be unduly small, so that the cooling effect by the cooling pipe 84 may be insufficient.

In the above-described embodiment of the present invention, on the other hand, the elastic member 85 can deform properly between the frame member 830 and the cooling pipe 84, so as to increase its contact area with respect to the cooling pipe 84 as it is being pressed. As a result, a larger contact area can be expected between the frame member 830 and the cooling pipe 84 than when no such member like the elastic member 85 is employed.

Further, by fixing the cooling pipe 84 under pressure with the elastic member 85 intervening, it is possible to ensure proper contact between the frame member 830 and the elastic member 85. In such an instance, the elastic member 85 is deformed between the frame member 830 and the cooling pipe 84, whereby the frame member 830 and the elastic member 85 are properly contacted with each other, and the contact area between the frame member 830 and the elastic member 85 increases as the pressing proceeds.

While the elastic member 85 is being pressed further, the contact area between the elastic member 85 and the cooling pipe 84 and the contact area between the frame member 830 and the elastic member 85 will increase to an extent which is not attainable when no deformation occurs and a mere contact is expected. Thus, the cooling effect by the cooling pipe 84 can be enhanced due to the enlarged contact area, in comparison with the case in which the elastic member 85 is not used.

As seen from the above, the elastic member 85 is made of a metal which is deformable under pressure and preferably a good heat conductor. More specifically, the elastic member 85 is preferably less hard than the frame member 830 and the cooling pipe 84, so that it can properly deform when press fixed. Thus, when the cooling pipe 84 and the frame member 830 are made of stainless steel, the elastic member 85 is made of a softer metal, for example, aluminum. The initial shape of the elastic member 85 is not limited to that shown in FIG. 6A, and may be corrugated as viewed in its cross section. Alternatively, the elastic member 85 may be made of an expanded metal.

With the above-described arrangement of the elastic member 85, heat is efficiently conducted from the frame member 830, through the elastic member 85 and the walls of the cooling pipe 84, and finally to the coolant flowing in the cooling pipe 84. Accordingly, heat present at the frame member 830 can be quickly drawn and dissipated by the coolant.

As shown in FIG. 5, use may be made of a plurality of brackets 86 at predetermined positions along the longitudinal direction of the cooling pipe 84 for pressure fixing the cooling pipe 84 to the frame member 830. The intervals between adjacent brackets may be determined suitably for each application. The elastic member 85 may be formed so as to extend longitudinally of the cooling pipe 84, to have generally the same length as the cooling pipe 84 or a shorter length than the pipe. When the elastic member 85 is shorter than the pipe, a plurality of elastic member 85 may preferably be used so that the overall contact area can be as great as possible. In such an instance, the lengths and positions of the elastic members 85 and brackets 86 with respect to the cooling pipe 84 may be determined by considering the cooling effect in the actual situation.

The workings of the work carrier A will be described below.

To deliver a work in the vacuum space, the work carrying mechanism 8 retains the work and moves it horizontally, and the scissors lift mechanism 4 is driven so as to vertically lift or lower the work carrying mechanism 8 as a whole. The rotation mechanism installed in the base unit 1 rotates the scissors lift mechanism 4 and the work carrying mechanism 8 together. With such an arrangement, the work can be carried in the three-dimensional space, from a predetermined initial position to a desired target position.

As shown in FIG. 2, when the scissors lift mechanism 4 is to be activated, the ball screw shaft 23 is rotated so that the nut block 24 is made to horizontally slide back and forth along the ball screw shaft 23. Since the end portions of the nut block 24 are connected to the lower end portions of the first and third arms 410, 420, respectively, the lower end portions of the arms 410, 420 are caused to slide along the slide rail 25.

As the lower end portions of the arms 410, 420 are caused to slide, the lower end portions of the second and fourth arms 411, 421 and the upper end portions of the first and third arms 410, 420 are caused to rotate about the brackets 21, 40A, and the upper end portions of the second and fourth arms 411, 421 are slave-driven to slide along the slide rail 40B. With such an arrangement, the stage 40 is vertically lifted or lowered while keeping the horizontal posture.

When the stage 40 is vertically lowered, for example to a position indicated by imaginary lines in FIG. 2 by the movement of the scissors lift mechanism 4, the work carrying mechanism 8 as a whole, unillustrated but mounted on the stage 40, is also lowered to the minimal height with reference to the base seat 2, whereby the hands 80 can be brought to the lowest possible level.

It should be noted that even when the stage 40 is brought to the lowest level by the scissors lift mechanism 4, there may be some vertical gap between the base seat 2 and the stage 40, due to the structural characteristics of the scissors lift mechanism 4. In light of this, the motor box 22 may preferably be disposed in the gap, so that it is possible not only to attain the vertical downsizing of the scissors lift mechanism 4, but also to effectively utilize the space above the base seat 2.

The height of the motor box 22 depends on e.g. the size of the lift driving motor 43, and hence it may not always be possible to properly accommodate the motor box 22 within the gap formed when the stage 40 is brought to the lowest position. For instance, when the stage 40 is lowered to the lowest position by the scissors lift mechanism 4, the motor box 22 would interfere with the stage 40 or the connection pipes 40E, 40G. This problem may be overcome by limiting the vertical movement range of the scissors lift mechanism 4 so that the motor box 22 is well spaced from the stage 40 or the connection pipes 40E, 40G. In this case, it is preferable to provide an additional mechanism for ensuring contact prevention. With these arrangements, the stage 40 may only be lowered to a level slightly higher than the lowest position that would otherwise be reached. However, the difference in height may be very small, the advantage of the downsizing in the vertical direction can still be enjoyed.

Another solution differing from the above is to locate the motor box 22 at a position where no interference with the stage 40 or the connection pipes 40E, 40G will occur. To this end, if necessary, the surface area of the base seat 2 may be increased. In this case, a gear box may be used between the lift driving motor 43 and the ball screw shaft 23, thereby increasing the degree of freedom in positioning the motor box 22.

When the the scissors lift mechanism 4 operates, the positional relations between the upper pipe 5, the intermediate pipe 6, the lower pipe 7, and the connection pipe 40E attached to the arms 410, 411, 420, 421 may change. The upper pipe 5, the intermediate pipe 6, the lower pipe 7, and the connection pipe 40E are communicatively connected rotatably to each other via the air-tightly sealed swivel joints J1, J3, J4 and the L-shaped joint J2. Thus, the internal coolant supply pipe and coolant discharge pipe are not adversely affected. Further, during the operation of the rotation mechanism, it is possible to prevent the coolant supply pipe and the coolant discharge pipe from being tangled or unduly twisted, whereby the proper routing condition of these pipes can be maintained along the arms 410, 411, 420, 421.

The work carrying mechanism 8 is most susceptible to thermal influence by radiant heat from the work heated. In this connection, since the belt sliding mechanism 81 and the guide rails 83C, 83D are required to maintain high dimensional precision for carrying the work, they have to be sufficiently isolated from the thermal influence. In the embodiment of the present invention, the cooling pipe 84 is disposed so as to surround the belt sliding mechanism 81 and the guide rails 83C, 83D. Thus, the coolant circulating through the cooling pipe 84 can efficiently cool the belt sliding mechanism 81 and the guide rails 830, 83D.

Specifically, the radiant heat from the work is transmitted to the frame member 830 via the hand 80. The frame member 830 is held in contact with the cooling pipe 84 over its entire length via elastic members 85 in the form of leaf springs. Thus, the heat from the frame member 830 is quickly transmitted to the coolant flowing inside the cooling pipe 84, via the elastic members 85 and the cooling pipe 84. Consequently, the thermal effect on the belt sliding mechanism 81 and the guide rails 83C, 83D can be mitigated, so that the work can be carried with high accuracy by the work carrying mechanism 8 that can be effectively cooled.

In accordance with the work carrier A of the above embodiment, the cooling pipe 84 is provided on the frame member 830 located close to the belt sliding mechanism 81 and the guide rails 83C, 83D, hence prone to suffer the radiant heat, where the cooling pipe 84 as a whole is brought into contact with the frame member via the elastic members 85. Such a structure provides a large contact area between the cooling pipe 84 and the frame member, thereby facilitating efficient heat dissipation from the frame member 830 and hence effectively suppressing thermal deformation of the belt sliding mechanism 81 or the guide rails 83C, 83D. Consequently the belt sliding mechanism 81 and the guide rails 83C, 83D, which play an important role in performing accurate work carrying, can be stabilized against heat so that the work can be carried with high accuracy.

The work carrier A described above includes the work carrying mechanism 8, the scissors lift mechanism 4, and the rotation mechanism, among which only the rotation mechanism needs to be located under the base seat 2. Thus, the height of the lower unit 1 accommodating therein the rotation mechanism can be reduced. Accordingly, the overall size of the work carrier A can be easily reduced by suppressing the height of the base seat 2, and further the size of the manufacturing equipment, in particular the height thereof, can be reduced. Such a compact lower unit 1 can be installed in an underfloor space that is advantageously shallow.

The coolant supply pipe and the coolant discharge pipe are laid in the pipeline extending from the base unit 1 to the work carrying mechanism 8. Thus, the routing condition of these pipes can be made stable, without disturbing the operation of the scissors lift mechanism 4 and the rotation mechanism.

Also, by vertically lowering the work carrying mechanism 8 with the use of the scissors lift mechanism 4, the height of the hands 80 with reference to the base seat 2 can be as small as possible.

The present invention is not limited to the above-described embodiments.

In the above embodiment, the elements J1, J3, J4 are swivel joints and the elements J2, J5 are non-rotating L-shaped joints. Differing from this, the elements J1, J2, J5 may be swivel joints and the elements J3, J4 may be L-shaped joints. In any case, swivel joints may be used to allow the rotation of the intermediate pipe 6 and the connection pipe 40E when the scissors lift mechanism 4 operates. If all the elements J2 to J5 were L-shaped joints, the intermediate pipe 6 and the connection pipe 40E would be non-rotatably connected at their ends, and hence the scissors lift mechanism 4 would not be operable. In light of this, in the above-described scissors lift mechanism 4, swivel joints are used for the element J1 and the element disposed at one end of each of the intermediate pipe 6 and of the connection pipe 40E, so that the scissors lift mechanism 4 can perform lifting or lowering movement without being subject to any restriction. In this connection, all the elements J1 to J5 may be swivel joints, but the cost can be reduced by using an L-shaped joint for some of the elements J1 to J5, as noted above.

The cooling pipe may be formed so as to have a semicircular cross section, instead of the rectangular one as in the foregoing embodiment. In this case, the flat surface of the cooling pipe is disposed so as to face the frame member, and the cooling pipe is pressure fixed to the frame member by a bracket, with an elastic member disposed between the cooling pipe and the frame member. In any case, the cooling pipe may need to have a flat contact surface to be brought into contact with an elastic member. This contact surface may cause no problem even if it is slightly bent or warped, but may preferably be as flat as possible for enabling better thermal conduction. In a case where the cooling pipe is formed to have a semicircular cross-section, the bracket is also made into a form corresponding to the shape of the cooling pipe. When the cooling pipe to be in contact with the elastic member has a flat surface, preferably the frame member may also have a flat surface facing the elastic member.

WORK CARRIER

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CPC

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Priority Claims (1)