Transport apparatus

Abstract

Provided is a transport apparatus capable of changing the transporting height of a transported article without requiring a large change in equipment and without decreasing the positional accuracy of the transported article.　A roller 14 and a roller 16 that protrude upward from a surface of transport via a conveyor in a work region are provided a prescribed front-back direction interval D1 apart from each other in the direction of pulling by the conveyor. A first groove 22a that allows the roller 14 to pass without making contact is formed in a lower surface of a transport plate 2. A first inclined portion 22b, where the groove depth becomes shallower, which contacts the roller 14 and presses up the transport plate 2 is provided to a rear end portion of the first groove 22a. A second groove 23a that allows an upper end portion of the roller 16 to enter therein is formed in a tip end portion of the transport plate 2. The second groove 23a comprises a second inclined portion 23b, where the groove depth becomes shallower, which contacts the roller 16 and presses up the transport plate 2. The interval D1 between the roller 14 and the roller 16 is the same as the interval D2 between the first inclined portion 22b and the second inclined portion 23b.

Description

Conveyor

[0001] The present invention relates to an apparatus for transporting a plate on which a workpiece is placed to a working area.

[0002] Japanese Patent Application Laid-Open No. 2000-16576 describes a device that transports a pallet carrying workpieces between a first area where people perform assembly work and a second area where a robot performs assembly work, using a roller chain conveyor or belt conveyor.

[0003] This conveying device includes a low-speed conveyor in a first area that conveys pallets at a low speed to match the speed of manual work, and a high-speed conveyor in a second area that conveys pallets at a high speed to match the speed of work by a robot. Because these conveyors share the same conveying line, their heights are set differently, so that the low-speed conveyor conveys pallets in the first area and the high-speed conveyor conveys pallets in the second area. Specifically, in the first area, the high-speed chain rail that vertically supports the rollers constituting the high-speed conveyor from below is positioned lower than the low-speed chain rail that vertically supports the rollers constituting the low-speed conveyor from below. This allows the low-speed conveyor to run at a higher position than the high-speed conveyor.

[0004] A height-adjusting plate is located at the point where the height of these conveyors changes. This height-adjusting plate gradually raises the surface that supports the rollers as the high-speed transport conveyor advances, and has an inclined surface that is inclined to a position higher than the upper surface of the low-speed chain rail, and a flat surface that is continuous with the inclined surface.

[0005] Therefore, the conveying device described in JP 2000-16576 A conveys pallets on a low-speed conveyor in the first area, and on a high-speed conveyor in the second area, so that the pallet's traveling speed can be made different between the first area and the second area.

[0006] According to the conveying device disclosed in JP 2000-16576 A, parts or transported products on a pallet placed on a conveyor are processed in the first or second area. In this case, the load associated with the processing may be applied to the rollers that make up the conveyor, so the conveyor must be strong enough to withstand not only the load associated with transportation but also the load associated with processing. This may require redesigning the conveyor's strength or changing its layout to ensure it is strong enough to withstand the load, which could increase the time and cost required for equipment modifications.

[0007] Furthermore, the conveying device disclosed in JP 2000-16576 A is configured to transfer pallets between a low-speed conveyor and a high-speed conveyor using a height-adjusting plate. That is, the high-speed conveyor is gradually pushed up by the height-adjusting plate, so that the upper surfaces of its rollers are higher than the upper surface of the low-speed conveyor. In addition, the front end of the pallet on the low-speed conveyor is pushed up so that it transfers from the low-speed conveyor to the high-speed conveyor. Then, the rear end is similarly pushed up and transferred to the high-speed conveyor, so that the entire pallet is placed on the high-speed conveyor and becomes nearly horizontal. In the conveying device disclosed in JP 2000-16576 A, the pallet tilts during this transfer, which can cause parts or products on the pallet to be misaligned, potentially causing problems with assembly or processing in the next process.

[0008] Furthermore, in order to increase the positional accuracy of the pallet or the parts or products placed on it, it is possible to connect the pallet and conveyor with connecting means such as pins. However, in a structure in which the pallet is tilted even temporarily, such as the conveying device described in JP 2000-16576 A, the clearance (play) in the connecting means must be large to allow for the tilt, which may cause a decrease in the positional accuracy of the pallet or the parts or products placed on it, or increase rattle during transport.

[0009] The present invention has been made in response to the above-mentioned technical problems, and aims to provide a conveying device that makes it possible to change the conveying height of the transported item without requiring major equipment modifications and without reducing the positional accuracy of the transported item.

[0010] In order to solve the above technical problems, the present invention provides a transport device having a conveyor that horizontally pulls a transport plate carrying a workpiece to be assembled to a predetermined work area, wherein at least two push-up protrusions that protrude above a transport surface of the conveyor in the work area are provided at a predetermined interval in a direction of pulling by the conveyor toward the work area, and a first groove that allows a first push-up protrusion that is rearward in the pulling direction of the two push-up protrusions to pass through without contact is formed on the underside of the transport plate, and a groove is provided at a rear end of the first groove in the pulling direction. A first inclined portion is provided which is shallower in depth and comes into contact with the first push-up protrusion to push up the conveying plate, and a second groove portion is formed at the tip of the conveying plate in the pulling direction to allow the upper end of the second push-up protrusion, which is the front of the two push-up protrusions in the pulling direction, to fit in, and the second groove portion has a second inclined portion which is shallower in depth and comes into contact with the second push-up protrusion to push up the conveying plate, and the distance between the first push-up protrusion and the second push-up protrusion is the same as the distance between the first inclined portion and the second inclined portion.

[0011] In the present invention, the first push-up protrusion portion and the second push-up protrusion portion may be arranged parallel to and spaced apart from each other in a width direction perpendicular to the traveling direction of the transport plate, and the first groove portion and the second groove portion may be formed parallel to the traveling direction and parallel to each other.

[0012] In the present invention, at least one of the first push-up protrusion and the second push-up protrusion may be configured as a pair of push-up protrusions spaced apart in the width direction.

[0013] In the present invention, the first push-up protrusion portion and the second push-up protrusion portion may have different protrusion heights from the conveying surface, and the groove depths of the first groove portion and the second groove portion may be different from each other.

[0014] In the present invention, when the protruding height of the first push-up protrusion and the protruding height of the second push-up protrusion are different and the groove depth of the first groove and the groove depth of the second groove are different from each other, the first push-up protrusion and the second push-up protrusion, and the first groove and the second groove may be arranged on the same straight line along the front-to-rear direction.

[0015] In the present invention, either the conveyor or the transport plate may have a protrusion protruding toward the other side, and the other of the conveyor or the transport plate may have a fitting hole into which the protrusion fits.

[0016] According to the present invention, at least two lift-up protrusions are provided in the working area, protruding above the conveying surface of the conveyor, and the lift-up protrusions are spaced a predetermined distance apart in the conveyor's pulling direction toward the working area. The underside of the conveying plate is formed with a first groove through which the rearmost first lift-up protrusion in the conveyor's pulling direction passes without contacting the work plate. The rear end of the first groove is provided with a shallow first inclined portion that contacts the first lift-up protrusion and lifts the conveying plate. Therefore, when the conveying plate is pulled by the conveyor, the first lift-up protrusion passes through the first groove and then contacts the first inclined portion. Therefore, the conveying plate is lifted by the vertical component of the load acting from the first lift-up protrusion on the first inclined portion.

[0017] The tip of the transport plate is formed with a second groove into which the upper end of the second, front-most, of the two push-up protrusions fits, and the second groove is provided with a second inclined portion that is shallower and contacts the second push-up protrusion to push up the transport plate. Therefore, when the transport plate is pulled by the conveyor, the second push-up protrusion fits into the second groove and then contacts the second inclined portion. Therefore, the transport plate is pushed up by the vertical component of the load acting from the second push-up protrusion on the second inclined portion.

[0018] Furthermore, since the distance between the first push-up protrusion and the second push-up protrusion is the same as the distance between the first inclined portion and the second inclined portion, the first push-up protrusion and the first inclined portion come into contact with each other at the same time that the second push-up protrusion and the second inclined portion come into contact with each other.

[0019] Therefore, when the conveyor pulls the transport plate, the transport plate rides on the first and second push-up protrusions, and is supported by the push-up protrusions in the work area. This prevents the load associated with assembly or processing from acting on the conveyor, or reduces the load acting on the conveyor. As a result, there is no need to redesign the conveyor's strength or change its layout due to changes in the load associated with assembly or processing, and the need for major equipment modifications can be reduced.

[0020] Furthermore, because the front and rear of the transport plate can be pushed up simultaneously, the transport plate can be pushed up without tilting in the front-to-rear direction. This prevents misalignment of the workpiece on the transport plate, preventing problems with assembly accuracy and processing in the work area. Furthermore, when the transport plate and the conveyor are connected by a connecting means such as a pin, the clearance of the connecting means can be reduced compared to when the transport plate is temporarily tilted. This improves the positional accuracy of the transport plate, allowing the workpiece to be positioned as desired in the work area. As a result, problems with assembly accuracy and processing in the work area can be prevented.

[0021] Furthermore, by configuring at least one of the first and second lifting protrusions as a pair of lifting protrusions spaced apart in the width direction of the transport plate, the transport plate can be lifted while maintaining a horizontal position. This improves the positioning accuracy of the transport plate, allowing the workpiece to be positioned as desired in the work area. As a result, it is possible to prevent problems with assembly accuracy and processing in the work area.

[0022] 6 is a perspective view illustrating an example of a conveying device according to an embodiment of the present invention. It is a schematic diagram illustrating a configuration in which a conveying plate is assembled to a slider. (a) is a rear view of the conveying plate showing a state in which one of each roller pair is in contact with an inclined portion, and (b) is a rear view of the conveying plate showing a state in which the other of each roller pair is in contact with an inclined portion. It is a cross-sectional view along line IV-IV in FIG. 3. It is a rear view illustrating an example of a conveying device equipped with two conveying units. It is a rear view illustrating an example in which the depth of a groove is adjusted so that two roller pairs pass through or come into rolling contact with one groove. It is a cross-sectional view along line VII-VII in FIG. 6. It is a rear view illustrating an example in which the groove width is adjusted so that two roller pairs pass through or come into rolling contact with one groove. It is a cross-sectional view along line IX-IX in FIG.

[0023] An example of the present invention will be described below with reference to the drawings. Note that the example described below is merely an example of the present invention and is not intended to limit the present invention.

[0024] FIG. 1 is a perspective view illustrating an example of a conveying device according to an embodiment of the present invention. The conveying device 1 shown in FIG. 1 is configured to convey workpieces W, supplied by a person or a robot, or supplied from a conveying line (not shown), to a work area where the workpieces W are assembled by an assembly robot (not shown). Specifically, the conveying device 1 includes a conveying plate 2 carrying the workpieces W. The conveying plate 2 is pulled horizontally by a linear conveyor 3 to the area where the robot performs the assembly work. The conveying plate 2 is then moved in the reverse direction to remove the assembled workpieces W. A new workpiece W is then supplied to the conveying plate 2 again, and the same process is performed. In other words, the conveying device 1 is configured to reciprocate the conveying plate 2. Note that the conveyor pulling the conveying plate 2 is not limited to the linear conveyor 3, and may be another type of conveyor, such as a roller conveyor or a belt conveyor.

[0025] The linear conveyor 3 is configured to drive a slider 4 by electromagnetic force. The slider 4 has an inverted U-shaped cross section and is disposed so as to cover a guide rail 5 having a rectangular cross section. That is, the slider 4 has an upper wall portion 4a facing an upper surface 5a of the guide rail 5, a first side wall portion 4b facing one side surface 5b of the guide rail 5, and a second side wall portion facing the other side surface of the guide rail 5.

[0026] Fig. 2 is a schematic diagram illustrating a configuration in which the transport plate 2 is assembled to the slider 4. In the example shown in Fig. 2, an existing slider 4 is used, and a fixed base 6 is fixed to the slider 4 to expand the mounting surface for assembling the transport plate 2. The fixed base 6 is formed to be longer than the slider 4 in the direction of movement of the slider 4, and is integrated with the upper surface of the slider 4 by bolts (not shown) or the like. The width of the fixed base 6 may be the same as that of the slider 4, or may be formed to be larger than that of the slider 4.

[0027] A transport plate 2 is placed on the upper surface of the fixed base 6. The transport plate 2 is larger than the fixed base 6 in the longitudinal direction (left-right direction in FIG. 1 ) and width direction (depth direction in FIG. 1 ), is integrated with the fixed base 6 in the longitudinal and width directions, and is provided so as to be liftable. Specifically, a cylindrical fixing portion 7 protruding toward the transport plate 2 is attached to the upper surface of the fixed base 6, and a through hole 8 into which the fixing portion 7 fits is formed in the transport plate 2. Therefore, by fitting the fixing portion 7 into the through hole 8 to assemble the transport plate 2 to the fixed base 6, the fixed base 6 and the transport plate 2 are integrated in the traveling direction and width direction of the slider 4, and the transport plate 2 can move in a direction away from the fixed base 6. In the example shown in FIG. 1 , four fixing portions 7 and four through holes 8 are formed. The fixing portion 7 corresponds to the "protrusion" in the embodiment of the present invention, and the through hole 8 corresponds to the "fitting hole" in the embodiment of the present invention. In addition, a fixed portion protruding toward the fixed base 6 may be formed on the transport plate 2, and a fitting hole into which the fixed portion fits may be formed on the fixed base 6, and the through hole 8 may be formed by a recess with a closed portion facing the tip of the fixed portion 7.

[0028] 2 , a stopper 9 is provided to prevent the transport plate 2 from being excessively spaced apart from the fixed base 6. Specifically, the transport plate 2 is formed with a recess 10 having a relatively large inner diameter and a through-hole 11 that penetrates the transport plate 2 from the center of the recess 10. The stopper 9, whose outer diameter at one end (upper end) is larger than the inner diameter of the through-hole 11, is integrated with the fixed base 6. Therefore, by assembling the stopper 9 after placing the transport plate 2 on the fixed base 6, when the transport plate 2 rises in a direction away from the fixed base 6, the upper end of the stopper 9 comes into contact with the bottom surface of the recess 10, thereby limiting the distance of the transport plate 2. That is, the upper limit of the distance of the transport plate 2 can be adjusted by adjusting the length of the stopper 9 or the length at which the stopper 9 is attached to the fixed base 6. For example, the upper limit of the distance can be set to 1 mm.

[0029] As shown in FIG. 1 , multiple types of workpieces W are placed on the transport plate 2. In the example shown in FIG. 1 , five types of workpieces W1, W2, W3, W4, and W5 are arranged in a line at a predetermined interval in the longitudinal direction of the transport plate 2 (the left-right direction in FIG. 1 ), and the various types of workpieces W1, W2, W3, W4, and W5 are also arranged in a line of five in the width direction of the transport plate 2. These workpieces W1, W2, W3, W4, and W5 are assembled by a robot (not shown). For example, the workpieces W1, W2, W4, and W5 are assembled to the workpiece W3 by an assembly operation that involves an assembly load, such as press-fitting, that presses the workpiece W toward the linear conveyor 3. Therefore, the positions (coordinates) at which the workpieces W1, W2, W3, W4, and W5 are arranged are determined to match the coordinate positions stored in the robot.

[0030] In addition, in order to position each workpiece W1, W2, W3, W4, and W5 or to prevent the workpieces W1, W2, W3, W4, and W5 from tipping over due to changes in speed, a socket or the like may be fixed to the transport plate 2 and the lower ends of each workpiece W1, W2, W3, W4, and W5 may be inserted into the socket.

[0031] 1, in the area where the robot assembles the workpieces W1, W2, W3, W4, and W5, support plates 12 and 13 are provided on both sides of the linear conveyor 3. Each of the support plates 12 and 13 supports four rollers rotatably at predetermined intervals in the pulling direction of the slider 4 (the traveling direction of the transport plate 2).

[0032] 1 , two rollers 14, 15 are provided on one side of the first support plate 12 on the front side, and two rollers 16, 17 are provided on the other side. Specifically, the two rollers 14, 15 on the trailing side (right side in FIG. 1 ) in the traveling direction of the slider 4 (hereinafter collectively referred to as a first roller pair R1) are provided on the side opposite the side facing the guide rail 5, and the two rollers 16, 17 on the leading side (left side in FIG. 1 ) in the traveling direction of the slider 4 (hereinafter collectively referred to as a second roller pair R2) are provided on the side facing the guide rail 5. That is, the roller pairs R1, R2 are arranged parallel to and spaced apart from each other in the width direction perpendicular to the traveling direction of the transport plate 2.

[0033] In addition, the first pair of rollers R1 is arranged to be located behind the center of gravity of the transport plate 2 in the pulling direction of the linear conveyor 3 when the transport plate 2 is positioned in the working area, and the second pair of rollers R2 is arranged to be located in front of the center of gravity.

[0034] 1, two rollers 18, 19 are provided on one side surface, and two rollers 20, 21 are provided on the other side surface. Specifically, the two rollers 18, 19 on the trailing side (the right side in FIG. 1) in the traveling direction of the slider 4 (hereinafter collectively referred to as a third roller pair R3) are provided on the side surface facing the guide rail 5, and the two rollers 20, 21 on the leading side (the left side in FIG. 1) in the traveling direction of the slider 4 (hereinafter collectively referred to as a fourth roller pair R4) are provided on the side surface opposite the side surface facing the guide rail 5. In other words, the roller pairs R3, R4 are arranged parallel to and spaced apart from each other in the width direction perpendicular to the traveling direction of the transport plate 2.

[0035] The third roller pair R3 is located behind the center of gravity of the transport plate 2 in the pulling direction of the linear conveyor 3 when the transport plate 2 is positioned in the working area, and the fourth roller pair R4 is located in front of the center of gravity. In other words, the first roller pair R1 and the third roller pair R3 are formed as a pair spaced apart in the width direction of the transport plate, and the second roller pair R2 and the fourth roller pair R4 are formed as a pair spaced apart in the width direction of the transport plate. The rollers 14, 15, 16, 17, 18, 19, 20, and 21 are supported at the same height in the vertical direction and are formed to have the same radius.

[0036] At least a portion of each of the roller pairs R1, R2, R3, and R4 is provided so as to protrude above the conveying surface of the linear conveyor 3. Specifically, a portion of each of the roller pairs R1, R2, R3, and R4 protrudes upward in the vertical direction above the upper surface of the fixed base 6. A plurality of grooves 22, 23, 24, and 25 are formed on the rear surface of the conveying plate 2, through which the portions of each of the roller pairs R1, R2, R3, and R4 protruding from the fixed base 6 pass and into rolling contact.

[0037] 3 shows a rear view of the transport plate 2, in which grooves 22, 23, 24, and 25 are formed in positions in the width direction of the transport plate 2 corresponding to the roller pairs R1, R2, R3, and R4. That is, a first groove 22 through which a portion of the first roller pair R1 passes and makes rolling contact, a second groove 23 through which a portion of the second roller pair R2 passes and makes rolling contact, a third groove 24 through which a portion of the third roller pair R3 passes and makes rolling contact, and a fourth groove 25 through which a portion of the fourth roller pair R4 passes and makes rolling contact are formed on the rear surface of the transport plate 2. That is, the grooves 22, 23, 24, and 25 are formed parallel to and spaced apart from one another in the width direction of the transport plate 2.

[0038] In addition, in the longitudinal direction of the transport plate 2, the first groove 22 and the third groove 24 are formed to have the same length, and the second groove 23 and the fourth groove 25 are formed to have the same length. Furthermore, as shown in Fig. 3(a), the lengths of the first groove 22 and the second groove 23 are determined so that when one roller 14 of the first roller pair R1 rides up the first groove 22, one roller 16 of the second roller pair R2 rides up the second groove 23. In other words, the distance D1 between the first roller pair R1 and the second roller pair R2 and the distance D2 between the end of the first groove 22 and the end of the second groove 23 are formed to be the same.

[0039] As shown in Figure 3(b), the distance d1 between the rollers 14, 15 in the first roller pair R1 and the distance d2 between the rollers 16, 17 in the second roller pair R2 are set to be the same so that at the time the other roller 15 in the first roller pair R1 climbs up the first groove 22, the other roller 17 in the second roller pair R2 climbs up the second groove 23.

[0040] 3A, the lengths of the third groove 24 and the fourth groove 25 are determined so that when one roller 18 of the third roller pair R3 rides up on the third groove 24, one roller 20 of the fourth roller pair R4 rides up on the fourth groove 25. In other words, the distance D3 between the third roller pair R3 and the fourth roller pair R4 and the distance D4 between the end of the third groove 24 and the end of the fourth groove 25 are formed to be the same.

[0041] As shown in Figure 3(b), the distance d3 between the rollers 18, 19 in the third roller pair R3 and the distance d4 between the rollers 20, 21 in the fourth roller pair R4 are set to be the same so that the other roller 21 in the fourth roller pair R2 climbs up the fourth groove 25 at the same time as the other roller 19 in the third roller pair R3 climbs up the third groove 24.

[0042] Figure 4 shows a cross-sectional view taken along line IV-IV in Figure 3. In Figure 4, the depth and inclination angle of the groove are exaggerated to illustrate the shape of the bottom surface of the groove. As shown in Figure 4, the first groove 22 has a horizontal bottom surface and includes a straight portion 22a whose depth is deeper than the amount by which the first roller pair R1 protrudes from the upper surface of the linear conveyor 3, and an inclined portion 22b whose depth gradually becomes shallower. The straight portion 22a is deep enough so that it does not come into contact with either of the rollers 14, 15 of the first roller pair R1 when the conveying plate 2 is in contact with the fixed base 6.

[0043] Therefore, when the leading end of the transport plate 2 moves to a position where it overlaps the roller 14, more specifically, when the roller 14 is positioned on the straight portion 22a, the roller 14 and the transport plate 2 do not come into contact with each other. As the transport plate 2 moves further and the roller 14 comes into contact with the inclined portion 22b as shown in FIG. 4 , a reaction force acting against the thrust of the transport plate 2 acts from the roller 14 to the inclined portion 22b. As described above, the transport plate 2 is integrated with the fixed base 6 by the fixed portion 7 in the direction of travel of the transport plate 2. Therefore, the transport plate 2 is pushed up by the vertical component (push-up load) of the reaction force acting on the inclined portion 22b. That is, the first groove 22 functions as a cam groove, and the roller 14 functions as a cam follower. The roller 14 corresponds to the "first push-up protrusion" in the embodiment of the present invention, the inclined portion 22b corresponds to the "first inclined portion" in the embodiment of the present invention, and the straight portion 22a corresponds to the "first groove" in the embodiment of the present invention.

[0044] 4, the second groove 23 is formed in the same manner as the first groove 22. That is, the second groove 23 has a horizontal bottom surface and includes a straight portion 23a whose depth is deeper than the amount by which the second roller pair R2 protrudes from the upper surface of the linear conveyor 3, and an inclined portion 23b whose depth gradually becomes shallower and which is formed at the same inclination angle θ2 as the inclination angle θ1 of the inclined portion 22b in the first groove 22. The straight portion 23a is formed to a depth such that it does not come into contact with either of the rollers 16, 17 of the second roller pair R2 when the conveying plate 2 is in contact with the fixed base 6.

[0045] The inclination angles θ1 and θ2 are preferably set to gentle angles to prevent the workpiece W from tipping over due to vertical acceleration when the transport plate 2 is pushed up, as will be described later, and can be determined based on the transport speed of the transport plate 2, the weight of the workpiece W, etc. For example, they can be set to 3.5 degrees, and preferably 5.0 degrees or less.

[0046] Therefore, when the leading edge of the transport plate 2 moves to a position where it overlaps the roller 16, more specifically, when the roller 16 enters the straight portion 22b, there is no contact between the roller 16 and the transport plate 2. At that time, the first roller pair R1 is positioned below the transport plate 2, but is located in the straight portion 22a of the first groove 22. Therefore, no upward load acts on the transport plate 2, and the transport plate 2 remains placed on the fixed base 6 and moves while maintaining a horizontal state.

[0047] As the conveying plate 2 moves further, the roller 16 comes into contact with the inclined portion 23b as shown in Figure 4. This inclined portion 23b is formed in the same shape as the inclined portion 22b in the first groove 22, and the roller 14 and the roller 16 are formed to have the same height and radius. Therefore, the second groove 23 functions as a cam groove, and the roller 16 functions as a cam follower. The roller 16 corresponds to the "second push-up protrusion" in the embodiment of the present invention, the inclined portion 23b corresponds to the "second inclined portion" in the embodiment of the present invention, and the straight portion 23a corresponds to the "second groove portion" in the embodiment of the present invention.

[0048] As described above, the inclination angles θ1, θ2 of the inclined portions 22b, 23b are the same, and the lengths of the first groove 22 and the second groove 23 are determined so that when one roller 14 of the first roller pair R1 climbs up the first groove 22, one roller 16 of the second roller pair R2 climbs up the second groove 23. Therefore, when the roller 16 comes into contact with the inclined portion 23b, the roller 14 also comes into contact with the inclined portion 22b. Therefore, the conveying plate 2 is pushed up by the vertical component (push-up load) of the reaction force acting on the inclined portion 22b and the vertical component (push-up load) of the reaction force acting on the inclined portion 23b.

[0049] When the transport plate 2 is pushed up by the load acting on each of the inclined portions 22 b and 23 b in this way, the amount of push-up at the inclined portion 22 b and the amount of push-up at the inclined portion 23 b relative to the horizontal movement of the transport plate 2 are the same. Therefore, the leading end of the transport plate 2 can be prevented from becoming higher than the trailing end in the movement direction, i.e., the transport plate 2 can be prevented from tilting. As a result, the workpiece W can be prevented from shifting in position or tipping over during the process of separating the transport plate 2 from the fixed base 6, thereby preventing interference with assembly and processing in the work area.

[0050] The third roller pair R3 and the fourth roller pair R4 are formed in the same manner as the first roller pair R1 and the second roller pair R2, and the third groove 24 and the fourth groove 25 are formed in the same manner as the first groove 22 and the second groove 23. That is, when the roller 14 contacts the inclined portion 22b of the first groove 22, the roller 16 contacts the inclined portion 23b of the second groove 23, the roller 18 contacts the inclined portion 24b of the third groove 24, and the roller 20 contacts the inclined portion 25b of the fourth groove 25. In other words, the rollers 14 and 18 function as a pair of cam followers spaced apart in the width direction of the transport plate 2, and similarly, the rollers 16 and 20 function as a pair of cam followers spaced apart in the width direction of the transport plate 2. Therefore, the rollers 14 and 18, or the rollers 16 and 20, correspond to a "pair of push-up protrusions" in the embodiment of the present invention.

[0051] Therefore, the transport plate 2 is supported at four points and the lift amounts at these four points are the same, so the transport plate 2 can be moved in the movement direction of the slider 4 while being lifted up while being maintained in a horizontal state. As a result, in the process of separating the transport plate 2 from the fixed base 6, it is possible to prevent the workpiece W from shifting out of position or tipping over, and to prevent problems with assembly and processing in the work area.

[0052] In order to horizontally push up the transport plate 2, it is sufficient to support it at at least three points, and only one of the third roller pair R3 and the fourth roller pair R4 is required. Furthermore, it is sufficient that the third roller pair R3 and the fourth roller pair R4 can push up the transport plate 2 simultaneously with the first roller pair R1 and the second roller pair R2, and the lengths of the first groove 22 and the third groove 24, and the lengths of the second groove 23 and the fourth groove 25 may be different.

[0053] Furthermore, because the transport plate 2 can be pushed up in a horizontal state, the clearance between the fixed portion 7 and the through-hole 8 can be made smaller compared to when the transport plate 2 is temporarily tilted. In other words, the positional deviation between the transport plate 2 and the fixed base 6 or slider 4 can be made smaller. Therefore, the positional accuracy of the workpiece W in the robot's work area can be improved, and the workpiece W can be positioned as desired. As a result, it is possible to suppress problems with assembly accuracy and processing in the work area, such as assembly errors and defective assembly of the workpiece W.

[0054] In addition, it is possible to prevent the transport plate 2 from being pushed up poorly due to the central axis of the through hole 8 being inclined relative to the central axis of the fixed portion 7, and it is also possible to prevent vibrations from occurring due to the elimination of uneven contact between the fixed portion 7 and the through hole 8, thereby preventing the workpiece W from shifting position or tipping over.

[0055] In the work area where the robot assembles the workpieces W, the transport plate 2 is supported by rollers, leaving a gap (e.g., 1 mm) between it and the fixed base 6. Therefore, even if the workpieces W are assembled on the transport plate 2, the assembly load can be supported by the roller pairs R1, R2, R3, and R4 and the support plates 12 and 13, which are independent of the linear conveyor 3. In other words, the load associated with processing does not act on the linear conveyor 3, or the load acting on the linear conveyor 3 can be reduced. In other words, the lift amount of the transport plate 2 is determined based on the strength of the transport plate 2, the assembly load, the distance between the rollers, etc., so that even if the transport plate 2 is bent by the assembly load acting on it, the bottom surface of the transport plate 2 will not come into contact with the top surface of the fixed base 6.

[0056] Therefore, the linear conveyor 3 only needs to have the function of transporting the workpiece W, and does not need to be designed for strength taking into account the assembly load, etc. As a result, when changing the workpiece W to be assembled, it is sufficient to change the strength of each roller pair R1, R2, R3, R4 and the support plates 12, 13, and there is no need to change the layout, which can suppress increases in time and costs associated with equipment changes.

[0057] 1, eight rollers are provided, and the eight rollers support the transport plate 2 when the transport plate 2 moves to the work area where the workpiece W is assembled by the robot. This reduces the load acting on each roller, and prevents the rollers from becoming too large.

[0058] The transport device according to the embodiment of the present invention is not limited to a device having one transport unit configured by a slider 4, a fixed base 6, and a transport plate 2 on a guide rail 5, but may also have two transport units. Specifically, the transport device may be configured so that a robot assembles a workpiece W at the center of the guide rail 5 in the longitudinal direction, with one transport unit reciprocating on one side and another transport unit reciprocating on the other side. In this case, grooves may be formed in each transport plate 2 according to the roller positions, as shown in FIG. 5 . That is, the right-side transport plate (first transport plate) 2r in FIG. 5 has a groove formed at the same position as the transport plate 2 shown in FIG. 3 , and the left-side transport plate (second transport plate) 2l has a groove formed at a position obtained by rotating the right-side transport plate 2r in a point-symmetrical manner. Note that each groove and inclined portion in the first transport plate 2r and each groove and inclined portion in the second transport plate 2l are formed in the same shape as the example shown in Figure 3, so in Figure 5, the grooves and inclined portions formed in the first transport plate 2r are indicated by the reference symbols shown in Figure 3 with an "r" added, and the grooves and inclined portions formed in the second transport plate 2l are indicated by the reference symbols shown in Figure 3 with an "l" added.

[0059] Therefore, a portion of the first roller pair R1 passes through and rolls into contact with the first groove 22r in the first transport plate 2r and the fourth groove 25l in the second transport plate 2l, a portion of the second roller pair R2 passes through and rolls into contact with the second groove 23r in the first transport plate 2r and the third groove 24l in the second transport plate 2l, a portion of the third roller pair R3 passes through and rolls into contact with the third groove 24r in the first transport plate 2r and the second groove 23l in the second transport plate 2l, and a portion of the fourth roller pair R4 passes through and rolls into contact with the fourth groove 25r in the first transport plate 2r and the first groove 22l in the second transport plate 2l.

[0060] By arranging the transport units on both sides of the area where the robot performs the assembly work, the rollers that push up the transport plate 2 can be shared, thereby making it possible to downsize the transport device. Also, while one transport plate 2r (2l) is being retracted from the assembly work area, the other transport plate 2l (2r) can be moved into the assembly work area, thereby shortening the overall assembly work time.

[0061] The transport plate 2 in the embodiment of the present invention is configured so that it is pushed up by at least two rollers at the same time in the longitudinal direction of the transport plate 2, and the two rollers do not have to be formed parallel to and spaced apart from each other in the width direction of the transport plate 2. That is, the first groove 22 and the second groove 23 shown in Figure 3 may be formed on the same line, and the third groove 24 and the fourth groove 25 may be formed on the same line. Specifically, two grooves 26 and 27 may be formed on the width direction of the transport plate 2 by adjusting the height or depth of the rollers as shown in Figures 6 and 7, or by adjusting the width of the rollers as shown in Figures 8 and 9.

[0062] 7 shows a cross-sectional view taken along line VII-VII in FIG. 6, in which the first roller pair R1 and the second roller pair R2 are arranged on the same straight line, and the second roller pair R2 is supported at a height higher than the first roller pair R1. The radii of the rollers are the same. That is, the first roller pair R1 and the second roller pair R2 protrude from the conveying surface at different heights.

[0063] The groove 26 is formed so that its depth becomes shallower in two stages from the tip of the transport plate 2. Specifically, from the tip side of the transport plate 2, a first straight portion 26a having a deeper groove depth, a first inclined portion 26b, a second straight portion 26c having a shallower groove depth, and a second inclined portion 26d are formed in this order.

[0064] The first straight portion 26a is formed at a depth such that the first roller pair R1 and the second roller pair R2 do not come into contact with each other, and its bottom surface is formed horizontally. The second straight portion 26c is formed at a position such that the first roller pair R1 does not come into contact with each other and is lower than the upper end of the second roller pair R2 when the transport plate 2 is placed on the fixed base 6. More specifically, the amount of vertical overlap between the bottom surface of the second straight portion 26c and the upper end of the second roller pair R2 when the transport plate 2 is placed on the fixed base 6 matches the amount of lift of the transport plate 2.

[0065] The first inclined portion 26b is an inclined portion that connects the first straight portion 26a and the second straight portion 26c, and is formed at the same inclination angle as the inclined portions 22b and 23b. The second inclined portion 26d is an inclined portion that connects the second straight portion 26c and the back surface of the conveying plate 2, and is formed at the same inclination angle as the first inclined portion 26b.

[0066] Furthermore, the second roller pair R2 (roller 16) is configured to contact the first inclined portion 26b when the first roller pair R1 (roller 14) contacts the second inclined portion 26d. That is, the first inclined portion 26b and the second inclined portion 26d are formed so that the distance D1 between the first roller pair R1 and the second roller pair R2 is the same as the distance D2 between the first inclined portion 26b and the second inclined portion 26d.

[0067] When the groove 26 is formed as described above, as the transport plate 2 moves, the first roller pair R1 moves relatively to the second inclined portion 26d without contacting the bottom surface or inclined surface of the groove 26. When the first roller pair R1 contacts the second inclined portion 26d, the second roller pair R2 contacts the first inclined portion 26b at the same time. Then, as the transport plate 2 moves further, the first roller pair R1 and the second roller pair R2 can push up the transport plate 2 while maintaining it in a horizontal state.

[0068] Therefore, even if the first roller pair R1 and the second roller pair R2 are arranged in the same straight line and the groove 26 corresponding to the first groove 22 and the second groove 23 is formed in the same straight line, the conveying plate 2 can be pushed up while maintaining a horizontal state, as in the case where a plurality of grooves through which each roller pair R1, R2 passes or contacts are formed, and the conveying plate 2 can be supported by the rollers in a state separated from the fixed base 6 during the assembling operation of the workpiece W. Note that the second straight portion 26c corresponds to the "first groove portion" in the embodiment of the present invention, the second inclined portion 26d corresponds to the "first inclined portion" in the embodiment of the present invention, the first straight portion 26a corresponds to the "second groove portion" in the embodiment of the present invention, and the first inclined portion 26b corresponds to the "second inclined portion" in the embodiment of the present invention.

[0069] 9 shows a cross-sectional view taken along line IX-IX in FIG. 8, in which the first roller pair R1 and the second roller pair R2 are arranged on the same straight line, and the axial length of the second roller pair R2 is longer than the axial length of the first roller pair R1. The radii of the rollers are the same.

[0070] The grooves 26 are formed so that their width narrows in two stages from the tip of the transport plate 2. Specifically, a wide groove 26e and a narrow groove 26f are formed in this order from the tip side of the transport plate 2, and the centers of the groove widths of the wide groove 26e and the narrow groove 26f are formed on the same straight line.

[0071] The wide groove 26e is wider than the axial length of the first roller pair R1, and a narrow groove 26f having a width substantially equal to the axial length of the first roller pair R1 is formed adjacent to the center of the tip of the wide groove 26e. The tip portions of the wide groove 26e and the narrow groove 26f are formed with inclined surfaces 26g and 26h having the same inclination angle as the inclined portions 22b and 23b. The distance D2 between these inclined surfaces 26g and 26h is the same as the distance D1 between the first roller pair R1 and the second roller pair R2.

[0072] When the grooves 26 are formed as described above, as the transport plate 2 moves, the first roller pair R1 moves relatively to the narrow groove 26f without contacting the bottom surface of the wide groove 26e or the inclined surface 26g, and contacts the inclined surface 26h at the tip of the narrow groove 26f. When the first roller pair R1 contacts the inclined surface 26h at the tip of the narrow groove 26f in this way, the second roller pair R2 contacts the inclined surface 26g of the wide groove 26e at the same time. Then, as the transport plate 2 moves further, the first roller pair R1 and the second roller pair R2 can push up the transport plate 2 while maintaining a horizontal state.

[0073] Therefore, even when one groove 26 is formed through which the first roller pair R1 and the second roller pair R2 pass or come into contact, the transport plate 2 can be pushed up while maintaining a horizontal state, just as in the case of forming multiple grooves through which the roller pairs R1 and R2 pass or come into contact, and the transport plate 2 can be supported by the rollers in a state separated from the fixed base 6 during the assembling operation of the workpiece W. Note that the narrow groove 26f corresponds to the "first groove portion" in the embodiment of the present invention, the inclined surface 26h corresponds to the "first inclined portion" in the embodiment of the present invention, the wide groove 26e corresponds to the "second groove portion" in the embodiment of the present invention, and the inclined surface 26h corresponds to the "second inclined portion" in the embodiment of the present invention.

[0074] In addition, the conveying device in an embodiment of the present invention is only required to be able to simultaneously push up and support the front and rear sides of the conveying plate in the direction of travel, and the number of points at which the conveying plate is pushed up and supported may be two or more.

Claims

1. A transport device having a conveyor which horizontally pulls a transport plate carrying a workpiece to be assembled to a specified working area, wherein at least two push-up protrusions protruding above a transport surface of the conveyor in the working area are provided at a specified interval in a direction of pulling by the conveyor towards the working area, a first groove is formed on the underside of the transport plate through which a first push-up protrusion which is the rearmost of the two push-up protrusions in the pulling direction passes without contact, a first inclined portion is provided at a rear end of the first groove in the pulling direction and pushes up the transport plate by contacting the first push-up protrusion, and a second groove is formed at a front end of the transport plate in the pulling direction and into which an upper end of a second push-up protrusion which is the frontmost of the two push-up protrusions in the pulling direction fits, and the second groove is provided with a second inclined portion which is shallower and contacts the second push-up protrusion to push up the transport plate, a distance between the first push-up protrusion and the second push-up protrusion and a distance between the first inclined portion and the second inclined portion are the same.

2. A conveying device as described in claim 1, characterized in that the first push-up protrusion portion and the second push-up protrusion portion are arranged parallel to and spaced apart from each other in the width direction perpendicular to the traveling direction of the conveying plate, and the first groove portion and the second groove portion are formed parallel to the traveling direction and parallel to each other.

3. A conveying device as claimed in claim 1, characterized in that at least one of the first push-up protrusion portion and the second push-up protrusion portion is composed of a pair of push-up protrusion portions spaced apart in the width direction.

4. A conveying device as described in claim 1, characterized in that the first push-up protrusion portion and the second push-up protrusion portion have different protruding heights from the conveying surface, and the first groove portion and the second groove portion have different groove depths.

5. A conveying device as described in claim 4, characterized in that the first push-up protrusion portion and the second push-up protrusion portion, and the first groove portion and the second groove portion are arranged on the same straight line along the front-rear direction.

6. A conveying device as claimed in any one of claims 1 to 5, characterized in that one of the conveyor and the conveying plate has a protrusion protruding to the other side, and the other of the conveyor and the conveying plate has a fitting hole into which the protrusion fits.

Images