JP2006111410A - Carried material lifting mechanism in carriage for suspension type lifting and conveying device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lifting mechanism element of a hand part for holding a carried material or releasing the hold in a carriage for a suspension type lifting and conveying device capable of preventing skip of a tooth in an engagement part of teeth parts of both a timing belt, which is formed from an elastic material and fixed to the hand part in one end and wound around a winding drum in the other end thereof for delivery, and a timing pulley for giving driving force to the timing belt. <P>SOLUTION: In any case of a case wherein pitch of the teeth 5a of the timing belt 5 when the hand part holds the carried material and raise it becomes the maximum and in a case wherein pitch of the teeth 5a of the timing belt 5 when the hand part is lowered without holding the carried material becomes the minimum, a clearance exists in the engagement part of the teeth part 5a of the timing belt 5 and a teeth part 14a of the timing pulley 14 formed from a rigid body and for driving the timing belt 5, and necessary engaging strength is given. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a suspended lifting / lowering transport device cart (hereinafter referred to as an OHT cart) that travels in a suspended state on a rail. The present invention relates to a mechanism that moves up and down by a plurality of timing belts that receive winding and feeding control.

For example, a carrier for storing and transporting a semiconductor wafer to sequentially perform various processes (cleaning, CVD, etc.) in a semiconductor manufacturing process, and a carrier for transferring a plate-like body to various processing units in liquid crystal manufacturing, FA, etc. In recent years, a suspension type lifting and lowering transport device (hereinafter referred to as OHT) has become the mainstream of transport means for transported objects such as these from the viewpoint of improving productivity.
The OHT lifts and lowers the object to be transported such as the carrier at a predetermined position by a lifting mechanism of the OHT cart, and transfers the OHT cart in a suspended state to a rail arranged along a predetermined track. It has a configuration to make it.

And the hand part which is provided in the OHT cart and grips the object to be transported such as a carrier or releases the gripped state and lifts the object to be transported is usually suspended by timing belts at four locations. Elevating operation is performed by winding and feeding.
In addition to the lifting / lowering function of the hand unit, the timing belt includes an electric power supply line for operating a clipper driving motor in the hand unit from the OHT cart body unit, a controller of the OHT cart body, and a hand unit. A communication line for exchanging signals between the controllers is embedded, and stable characteristics are required for repeated winding and feeding. For this reason, the timing belt is rich in flexibility, and a material having a predetermined strength is used (see, for example, Patent Document 1).

In addition, the length of the timing belt is approximately 2.7 m, and the load applied to the timing belt varies greatly depending on whether the hand unit grips a transported object such as a carrier or not. The fluctuating load is about 4 kg per timing belt.
When a carrier having a weight of about 16 kg is held by the four timing belts having a length of 2.7 m, if the timing belt has a variation, the object to be transported held by the hand portion is tilted to form four timing belts. The applied load becomes non-uniform, and the elastic elongation of the timing belt also varies. Along with this, the inclination of the conveyed object is further enlarged, and there is a risk that the timing belt may cause a tooth skipping phenomenon (hereinafter referred to as tooth skipping) at a portion where the timing pulley is engaged. This tooth jump often occurs due to an unbalance of tension caused by the inertial force applied to the four timing belts as the conveyed object moves in the direction of gravity when the conveyed object moves up and down.

If tooth skipping occurs at the biting site between the timing belt teeth and the timing pulley teeth, the timing belt that caused the tooth skipping cannot mesh with the regular teeth of the timing pulley and skip one pitch. Since the next tooth portion meshes, the object to be transferred (wafer storage carrier or the like) partially slides down with a length corresponding to one pitch and stops. This sliding phenomenon is observed as a hunting phenomenon in appearance. When the timing belt thus causes a hunting phenomenon, an impact force acts on the object to be conveyed. For example, when the object to be conveyed is a carrier containing a wafer, the wafer stored in the carrier is the inner wall surface of the carrier. Cause slipping or collision between the two and the like, generating particles due to friction, lowering the quality and yield of the wafer, and if a severe hunting phenomenon occurs, the carrier as a transported object may fall.
In addition, a local impact force is applied to the timing belt teeth due to the hunting phenomenon, and the life of the timing belt is significantly shortened.

Parameters that induce such tooth skipping, and thus hunting, include (A) timing pulley tooth geometry (B) timing belt tooth geometry (C) timing belt elastic modulus.
Incidentally, there is Patent Document 2 as a prior art of each invention of the present application. In Patent Document 2, as part of a timing belt drive mechanism in an OHT carriage, a timing belt 11 having a tooth portion, a roller 20 that winds and feeds the base end portion thereof, and teeth of the timing belt 11 are provided. There is disclosed a timing pulley 12 that is provided with meshing teeth and that drives the timing belt 11 in a direction in which the timing belt 11 is fed out from the winding roller 20 or wound around the winding roller 20.

And although not directly related to the invention according to Patent Document 2, as part of preventing tooth skipping of the meshing of the teeth in the timing belt 11 and the timing pulley 12, a pinch roller 13 that presses the timing belt 11 against the timing pulley 12, 14 and a guide roller 15 that prevents the timing belt 11 from swinging in the width direction are disclosed.
Further, in Patent Document 2, as a control means for raising and lowering the object to be conveyed, if the timing belt 11 is loosened between the timing pulley 12 and the take-up roller 20, vibration is likely to occur and the object to be conveyed is detected. The technique which considered that the balance of the suspension posture of this becomes easy to collapse is disclosed.

More specifically, the rotational driving force is applied to the winding roller 20 so that the circumferential speed of the winding roller 20 is larger than the circumferential speed of the timing pulley 12, and the rotational driving force is limited and cut off by the slip clutch 21. enable. Next, when the timing belt 11 is wound (when the conveyed object is raised), the timing belt 11 is wound around the winding roller 20 at a speed higher than the feeding speed of the timing pulley 12, so that the winding roller 20 and Winding is performed while tension is applied between the timing pulleys 12, and when the tension increases above a predetermined value, the rotational driving force is limited by the slip clutch 21, whereby the timing belt is controlled by the tension limited below the predetermined value. 11 is prevented from occurring.
On the other hand, at the time of rewinding (when the object to be transported is lowered), the transmission of the rotational driving force in the slip clutch 21 is cut off, and the winding roller 20 is made freely rotatable to be in a state of being driven by the timing pulley 12. The tension is generated in 11 to prevent the slack.

JP 2000-281278 A JP 2000-109285 A

As means for preventing tooth skipping occurring at the meshed portions of the timing belt and timing pulley disclosed in Patent Document 2, a pinch roller and a timing belt that press the timing belt against the timing pulley are used. There is a disclosure of a guide roller that suppresses displacement in the width direction.
However, although these pinch rollers and guide rollers have an effect of preventing tooth skipping at the meshing portions of the timing belt and the timing pulley, they are not sufficient.
On the other hand, as shown in FIG. 5 as a developed schematic view, the meshing portions of the tooth portions of the conventional timing belt and timing pulley are tight in the timing belt 50 and the timing pulley 51. Conventional means to be engaged were used.

In such tight meshing, the parameters (A), (B), and (C) that cause the tooth skipping are not taken into consideration, so when raising and lowering the object to be conveyed in the OHT carriage, for example, When an unexpected vibration occurs and tooth skipping starts, if there is a portion where there is no clearance in the meshing portions of the tooth portions 50a and 51a, the restoring force to the normal state is weak.
Therefore, tooth skipping spreads from the place where the tooth jump occurs, and the tooth portions of the timing belt and the timing pulley mesh with each other with a shift of one pitch, and are suspended by other timing belts that do not cause tooth skipping. If the object to be conveyed cannot maintain a normal posture and the object to be conveyed is, for example, a carrier containing a wafer, the quality of the wafer may be deteriorated. In an extreme case, the object to be suspended is suspended by an OHT carriage. There is a risk of transported items falling.

  Accordingly, an object of the present invention is to provide a timing pulley and a timing belt in consideration of (A) timing pulley tooth geometry, (B) timing belt tooth geometry, and (C) timing belt elasticity. In order to prevent tooth skipping by setting the clearance of the meshing part of each tooth part so that, in principle, tooth skipping does not occur or even if tooth skipping occurs, it can be restored to normal at the initial stage of occurrence. is there.

Means and effects for solving the problems

In order to solve the above-mentioned problem, the lift mechanism of the transported object in the OHT cart according to claim 1 has a belt-like shape, and on one surface thereof, a tooth portion is formed along the longitudinal direction for gripping the transported object. A plurality of timing belts that support the hand part at the lower end part, a timing pulley that meshes with each tooth part of each timing belt and controls the hand part suspended by the timing belt, and each timing In the lifting mechanism of the object to be transported in the carriage for the lifting type lifting and lowering conveying device having a winding roller for winding or feeding each corresponding timing belt by driving control of the pulley, each of the timing belt and the timing pulley The meshing state of the tooth parts is due to the elastic expansion and contraction of the timing belt depending on the presence or absence of a load corresponding to the presence or absence of the loaded object. Therefore, even if the tooth pitch of the timing belt that fluctuates and the tooth pitch of the timing pulley that does not cause elastic expansion / contraction are displaced, the tooth width dimension of the timing belt and the tooth width dimension of the timing pulley are optimized. By doing so, it is configured to maintain a predetermined meshing strength without causing a meshing failure.

According to the first aspect of the present invention, even if the timing belt elastically expands and contracts due to the presence or absence of gripping of the object to be conveyed in the hand portion of the OHT carriage, the timing belt and the timing pulley are further taken into consideration. By forming each tooth portion of the timing belt and the timing pulley so that the clearance can be increased within a range in which the meshing state between the tooth portions maintains a predetermined strength, tooth skipping at the meshing portion of each tooth portion can be prevented. .
That is, at the stage where tooth skipping starts to occur due to vibration and other factors at the meshing portions of the tooth portions, the meshing state of the tooth portions is tight with little clearance as in the conventional means. In the state, with the expansion and contraction of the timing belt, the clearance disappears, and the configuration of the invention of claim 1 of the present application shifts in the direction of suppressing the tooth skip as compared with the shift to the tooth skip.

The lift mechanism of the transported object in the OHT cart according to claim 2 is the lift mechanism of the transported object in the OHT cart according to claim 1, in the vicinity of each timing pulley, In addition, a guide roller is provided between the conveyed objects, the timing pulley, and the winding roller corresponding to the timing pulley, and prevents a displacement in the width direction of the timing belt.
According to the second aspect of the present invention, in addition to the effect of the first aspect of the present invention, the displacement of the timing belt located in the vicinity of the timing roller in the width direction can be suppressed. It is possible to increase the effect of preventing tooth skipping at the meshing portion of each tooth portion.

The lift mechanism of the transported object in the OHT cart according to claim 3 is the lift mechanism of the transported object in the OHT cart according to claim 1 or 2, wherein each timing pulley and a timing belt corresponding thereto are provided. In one to a plurality of locations where each tooth portion meshes, a pinch roller that presses a portion where the tooth portion of the timing belt is not formed in the timing pulley direction is provided.
According to the invention according to claim 3, in addition to the effect of the invention according to claim 1 or 2 of the citation source, it is possible to further improve the tooth skip suppression effect of the timing belt.
That is, the pinch roller has an effect of blocking and mitigating the momentary inertial momentarily applied to the timing belt when propelling the conveyed object, and propagating to the timing belt teeth.

The lift mechanism of the transported object in the OHT cart according to claim 4 is a structure in which the number of timing belts is four in the lift mechanism of the transported object in the OHT cart according to claim 1. It was.
According to the invention according to claim 4, in addition to the effects of the inventions according to claims 1 to 3 of the citation source, it is easy to assemble the synchronous operation mechanism in all the timing pulleys, and the hand portion that grips the object to be conveyed. Can be suspended in a stable state.

The lift mechanism of the transported object in the OHT cart according to claim 5 corresponds to each timing pulley in the lift mechanism of the transported object in the OHT cart according to any one of claims 1 to 4. Control means for keeping the tension of the timing belt between the winding roller constant within a predetermined range is provided.
According to the invention of claim 5, in addition to the effects of the inventions of claims 1 to 4 of the citation source, the slack of the timing belt between each timing pulley and the winding roller corresponding thereto, and Since the accompanying vibration can be prevented, the tooth belt skipping effect of the timing belt can be further improved.

The lift mechanism of the transported object in the OHT cart according to claim 6 is the lifting mechanism of the transported object in the OHT cart according to any one of claims 1 to 5, wherein each timing belt is moved to the hand unit. Electric power required for power generation or control signal supply is embedded in the power supply.
According to the invention according to claim 6, in addition to the effect of the invention according to claim 1 or 5 of the citation source, in general, it is necessary for transmission and reception of power and signals between the OHT carriage main body and the transported object gripping hand portion. It is not necessary to separately provide a 3 m electric wire, and the wiring can be simplified.
Incidentally, if the electric wire is separately arranged instead of the electric wire embedded in the timing belt, it becomes necessary to separately provide an expansion / contraction mechanism for the electric wire, resulting in a complicated structure.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
First, the outline of the drawings will be described. FIG. 1 is a front view showing the configuration of the main part of the OHT cart according to the present invention, FIG. 2 is a schematic configuration diagram of the lifting mechanism in the hand portion of the OHT cart, and FIG. FIG. 4 is a schematic configuration diagram showing a main part configuration of the present invention, FIG. 4 is a developed schematic view in a meshing portion (region M portion in FIG. 3) of each tooth portion of the timing belt and the timing pulley, and FIG. When the belt tension is maximum (maximum length), FIG. 5B shows the situation when the tension of the timing belt is minimum (length is minimum). FIG. 5 is a developed schematic view of the meshing portion (region M in FIG. 3) of each tooth portion of the timing belt and timing pulley as conventional means, and FIG. 6 is a dimension display of the timing pulley and timing belt in the embodiment of the present invention. (A) is a dimension display of a timing belt, and (B) is a dimension display of a timing pulley. FIG. 7 is a characteristic diagram showing the relationship between the load of the conveyed object and the timing belt in the embodiment of the present invention.

As shown in FIG. 1, the OHT carriage 1 is suspended from a traveling rail 2 provided along a predetermined track on the ceiling. The OHT carriage 1 travels in the guide / drive unit 3 while being regulated by the travel rail 2 with travel wheels and guide wheels (not shown). In this case, the required power is a well-known means such as a driving motor provided on the traveling wheel, or a DC linear motor provided with a secondary side and a primary side on the rail 2 side and the OHT carriage 1 side, respectively. Obtained by. Reference numeral 4 denotes an alignment mechanism for adjusting displacement in a direction orthogonal to the traveling direction of the OHT carriage and the rotational direction of the transported object 2 to be described later on the traveling rail 2. Four timing belts are provided on the front, rear, left, and right, and are configured to be able to expand and contract by an elevating mechanism 6 (details will be described later) provided in the OHT cart 1 so as to elevate and lower the hand unit 7. The timing belt 5 has an electric power supply (not shown) for power supply to the hand unit 7 and transmission / reception of control signals embedded therein.

Reference numeral 7a denotes a gripper member, which is one of the components of the hand unit 7, and is supported so as to be displaceable in the illustrated left-right direction. Reference numeral 8 denotes an object to be conveyed. As a specific example, a carrier body 8a containing a wafer that has not been processed or processed in various processes such as cleaning, CVD, and a flange portion 8b that receives or releases the grip by the clipper member 7a. Consists of

Next, a specific configuration of the lifting mechanism 6 will be described with reference to FIG. In FIG. 2, the elevating mechanism 6 includes an accommodation frame body 11 formed in a substantially rectangular parallelepiped shape, and four suspension modules 12 accommodated in the accommodation frame body 11. Each suspension module 12 includes a timing belt 5 that suspends the object 8 to be conveyed via the hand unit 7, a winding drum 13 that rewinds and winds the timing belt 5, a rewind direction of the timing belt 5, and And a timing pulley 14 that feeds in the winding direction, and a drum drive motor 15 that is a DC motor that rotationally drives the winding drum 13 to be switchable between the rewinding direction and the winding direction.

Next, the detailed structure of each suspension module 12 will be described. The drum drive motor 15 of each suspension module 12 is arranged so that the axis of the drive shaft 15 a coincides with the longitudinal direction of the housing frame 11. A drive shaft 15 a of the drum drive motor 15 is provided through the center of the winding drum 13. Further, the distal end portion of the drive shaft 15 a is rotatably supported by the bearing member 16. The drum drive motor 15 rotates the winding drum 13 with an arbitrary driving force so that the winding drum 13 can be switched between a rewinding direction and a winding direction.

The timing belt 5 is bent in a curved shape along the periphery of the timing pulley 14 and then dropped, and the other end is connected to the hand portion 7 (see FIG. 1). The timing pulley 14 is arranged in parallel to the side of the winding drum 13 at an intermediate position between the hand portion 7 and the winding drum 13. The timing pulley 14 and the timing belt 5 are provided with teeth described later. The timing pulley 14 and the timing belt 5 are engaged with each other to achieve reliable belt conveyance without slipping during normal operation.

The suspension module 12 configured as described above is arranged at positions corresponding to the four corners of the upper surface shape (rectangular shape) of the hand portion 7 so as to stably suspend the hand portion 7 shown in FIG. Yes. That is, the suspension module 12 is arranged in a state of 2 rows and 2 columns in the longitudinal direction and the width direction of the housing frame 11, and is provided point-symmetrically with respect to the array center of 2 rows and 2 columns. Further, the two suspension modules 12 and 12 arranged in parallel in the longitudinal direction of the housing frame 11 are set so that the rotation centers of the timing pulleys 14 and 14 are concentric. A first pulley drive shaft 17 extends through the center of rotation of the timing pulleys 14 and 14 in the suspension modules 12 and 12 on one side. In addition, a second pulley drive shaft 18 extends through the center of rotation of the timing pulleys 14 and 14 in the suspension modules 12 and 12 on the other side. These pulley drive shafts 17 and 18 are rotatably supported by a bearing unit 19.

Bevel gears 20 and 20 are provided at one ends of the pulley drive shafts 17 and 18, respectively. A third pulley drive shaft 21 is disposed on one end side of both pulley drive shafts 17 and 18. The third pulley drive shaft 21 is set to be orthogonal to both pulley drive shafts 17 and 18. The third pulley drive shaft 21 is rotatably supported by the bearing bearing unit 19. Also, bevel gears 20 and 20 are provided at both ends of the third pulley drive shaft 21. The bevel gears 20 and 20 of the third pulley drive shaft 21 are meshed with the bevel gears 20 and 20 provided at one ends of the first and second pulley drive shafts 17 and 18, respectively. Thereby, the timing pulley 14 of each suspension module 12 is connected by the first to third pulley drive shafts 17, 18, and 21.

A lifting motor 22 is connected to the other end of the first pulley drive shaft 17. The elevating motor 22 is a servo motor, and the elevating motor control device 23 can feedback control the rotation direction and the rotation speed. On the other hand, the drum drive motor 15 is a DC motor, and the rotation direction and the rotation speed can be controlled by the drum drive motor control device 24. The reason why a DC motor is used as the drum drive motor 15 is that the rotation speed is changed to the rotation speed of the timing pulley 14 (the rotation speed of the elevating motor 22) by controlling the voltage and current of the drive voltage as basic characteristics of the DC motor. This is because the tension generated in the timing belt 5 between the timing pulley 14 and the winding drum 13 can be controlled to be a constant value within a predetermined range. These motor control devices 23 and 24 increase the circumferential speed of the winding drum 13 more than the circumferential speed of the timing pulley 14 when the timing belt 5 is wound, while when the timing belt 5 is rewound. The peripheral speed of the winding drum 13 is controlled to be lower than the peripheral speed of the timing pulley 14.

The configuration shown in FIG. 1 and FIG. 2 shows one specific example of application of each invention of the present application, and its operation will be described as follows.
First, when a transport command signal from a main controller (not shown) is received by the control unit of the OHT carriage, the signal content included in the transport command signal is read. Specifically, based on the signal content of the conveyance command signal, a designated location of a processing device (not shown) as a conveyance destination is recognized, and a travel route for reaching this designated location (travel position data) is determined. The

Thereafter, the OHT carriage 1 generates a traveling magnetic field by passing a three-phase alternating current through a secondary coil constituting a linear motor (not shown), and a secondary permanent magnet (not shown) laid on the transport track. ) Starts running with the propulsive force generated by the magnetic action with the permanent magnet. During travel, the travel route is confirmed based on the track position data by bar code display or the like provided in the transport track. When the designated location is reached, the position of the OHT carriage 1 is finely adjusted using the correction data stored in advance by teaching, and then the removal of the transported object 8 is performed on the processing apparatus existing at the designated location.

When the transported object 8 is attached to the processing apparatus (the timing belt 5 is lowered), the lifting motor control device 23 performs feedback control so that the lifting motor 22 rotates at a predetermined rotational speed in the rewinding direction. The first pulley drive shaft 17 connected to the elevating motor 22 rotates in the rewinding direction, and the third pulley drive shaft 21 and the second pulley connected to the first pulley drive shaft 17 by meshing the bevel gear 20 The pulley drive shaft 18 rotates in the same direction. As a result, the timing pulley 14 of each suspension module 12 through which the first pulley drive shaft 17 and the second pulley drive shaft 18 are inserted starts to rotate simultaneously in the rewind direction.

In addition to the rotation of the lifting motor 22 by the lifting motor control device 23, each drum drive motor control device 24 outputs a predetermined voltage and current to the drum drive motor 15 of each suspension module 12, and the drum drive motor 15 is turned on. Rotate in the rewind direction. Thereby, the drum drive motor 15 rotates the winding drum 13 in the rewinding direction via the drive shaft 15 a, and the timing belt 5 is rewound from the winding drum 13. At this time, the drum drive motor control device 24 controls the tension and tension generated in the timing belt 5 between the timing pulley 14 and the winding drum 13 to be constant within a predetermined range by controlling the voltage and current of the drive power supply.

As a result, the timing belt 5 of the entire suspension module 12 is rewound from the winding drum 13 at the same speed, so that the hand portion 7 suspended from the timing belt 5 is lowered while maintaining a horizontal state. Accordingly, since the tilt of the transported object 8 is prevented, the yield of the product due to the stored object such as the wafer in the transported object 8 slipping or hitting the side wall of the transported object 8 is prevented. The

Further, when the lowering is performed, since the tension of the timing belt 5 between the winding drum 13 and the timing pulley 14 is set within a predetermined range, the winding drum 13 is lowered with a weak tension while being driven by the timing pulley 14. As described above, the timing belt 5 does not lift from the timing pulley 14 to disengage the mesh. Thereby, since the timing belt 5 and the timing pulley 14 are reliably engaged with each other, it is possible to prevent an accident that the conveyed object 8 falls out of balance and falls. Moreover, since the timing belt 5 is tensioned with a predetermined range of tension, it is possible to prevent the timing belt 5 from being damaged or worn out at an early stage.

Next, when the transported object 8 is lowered and placed at a predetermined position of the processing apparatus, this placement state is detected by a placement detection sensor (not shown). Then, after the descending of the transported object 8 is stopped, the holding of the transported object 8 by the hand unit 7 is released. Thereafter, only the hand portion 7 is pulled up to complete the mounting of the transported object 8.

On the other hand, when the transported object 8 is removed from the processing apparatus (the timing belt 5 is raised), first, the elevating mechanism 6 is operated so as to execute the lowering operation, and the empty hand unit 7 is moved to the timing belt. It is lowered in the direction of the conveyed object 8 while being suspended by 5. Accordingly, even in this case, since the timing belt 5 is engaged with the timing pulley 14 under a tension within a predetermined range, there is little possibility that the engagement is disengaged in a normal state. Thereafter, when it is detected by a placement detection sensor (not shown) that the hand portion 7 has reached the flange portion 8b of the object 8 to be conveyed, the hand portion 7 stops the descent and then the hand portion 7 causes the flange portion 8b to stop. Is retained.

Next, as shown in FIGS. 1 and 2, the lifting motor control device 23 performs feedback control so that the lifting motor 22 rotates in the winding direction at a predetermined rotational speed. As a result, the first to third pulley drive shafts 17, 21, and 18 connected to the elevating motor 22 sequentially rotate while changing the rotation direction. As a result, the timing pulley 14 of each suspension module 12 through which the first pulley drive shaft 17 and the second pulley drive shaft 18 are inserted starts to rotate simultaneously in the winding direction.

In addition to the rotation of the lifting motor 22 by the lifting motor control device 23, each drum drive motor control device 24 outputs a predetermined voltage and current to the drum drive motor 15 of each suspension module 12, and the drum drive motor 15 is turned on. Rotate in the winding direction. Accordingly, the timing belt 5 is wound around the winding drum 13 by the drum driving motor 15 rotating the winding drum 13 in the winding direction via the drive shaft 15a. As in the case of lowering the transported object 8, the drum drive motor control device 24 generates the timing belt 5 between the timing pulley 14 and the winding drum 13 by controlling the voltage and current of the drive power supply. The tension is controlled to a constant value within a predetermined range.

FIG. 3 is a schematic configuration diagram in which a main part of the configuration according to each invention of FIG. 2 showing the gripping of the object to be conveyed 8 and the entire mechanism of the hand unit 7 for releasing the gripping is extracted, and additional elements are added. In FIG. 3, the mutual relationship between the components shown in FIG. 2 (the timing belt 5, the timing pulley 14 and the winding drum 13 in the suspension module 12) will be described in detail as follows.
First, the timing pulley 14 and the timing belt 5 are formed with teeth 14a around the timing pulley 14 in order to prevent slippage at the relative positions of the contact portions with each other. The tooth part 5a which meshes with the tooth part 14a is formed. Next, the configuration of the winding drum 13 will be described. A cylindrical portion 13a for winding the timing belt 5, a flange portion 13b for preventing displacement of the wound timing belt 5 in the width direction, and
A fixing portion 13c is provided.

In addition, this fixing | fixed part 13c is provided in the inside of the cylindrical part 13a in order to hold | maintain the edge part 5b of the timing belt 5 wound up by the cylindrical part 13a reliably.
Reference numerals 31 and 32 denote pinch rollers that rotate while pressing the back surface of the timing belt 5 (the surface on which the tooth portions 5a are not formed) at the meshing portions of the tooth portions 5a and 14a of the timing belt 5 and the timing pulley 14. It is supported freely.
As a result, at least in the M section between the pinch rollers 31 and 32, the timing belt is wound around the timing pulley in a state where tension is applied, and the two places on the back are pressed by the pinch roller. The teeth of the timing belt are in close contact with the teeth of the teeth, and there is little possibility of occurrence of tooth skipping at the meshing portions of the teeth 5a and 14a of the timing belt 5 and the timing pulley 14.

Reference numerals 33 and 34 denote guide rollers, which contact the cylindrical portions 33a and 34a on the back surface of the timing belt 5, and suppress displacement in the width direction of the timing belt 5 by the flange portions 33b and 34b. The arrangement positions are the timing belt 5 and the timing pulley 14. It is set as the vicinity of the meshing site | part of each tooth | gear part 5a, 14a.
Accordingly, when the timing belt 5 is swung in the width direction of the timing belt 5 at the end of the timing belt 5 on the side opposite to the take-up drum 13, the teeth of the timing belt 5 with respect to the teeth 14 a of the timing pulley 14 are generated. It is possible to suppress tooth skipping that may occur when the meshing of the portion 5a is inclined.

In the above description,
(1) Applying a constant tension within a predetermined range to the timing belt 5 between the winding drum 13 and the timing pulley 14 (2) Providing pinch rollers 31 and 32 (3) Providing guide rollers 33 and 34 The tooth belt 5 and the timing pulley 14 have the effect of suppressing the occurrence of tooth skipping at the meshing portions of the tooth portions 5a and 14a.

In the configurations (1) to (3), vibrations and impact forces that are expected to occur when the conveyed object 8 is raised and lowered are applied to the meshing portions of the tooth portions 5 a and 14 a of the timing belt 5 and the timing pulley 14. Propagation is blocked, and tooth jumping is prevented.
However, when the conventional clearance is minimal and tight meshing is performed at the meshing portions of the teeth 5a and 14a of the timing belt 5 and the timing pulley 14, the timing pulley 14 does not vary in tooth pitch due to high rigidity. As a result of being formed of an elastic body, the meshing state of the tooth portion 5a of the timing belt 5 having a variation in the tooth portion pitch changes depending on the presence or absence of the conveyed object 8, and the optimum state is maintained. Can not.

That is, the tooth part 14a of the timing pulley 14 where the tooth part pitch does not change and the tooth part 5a of the timing belt 5 where the tooth part pitch changes are in a state where the hand part 7 does not grip the object 8 (the hand part 7 is From the state of the lowest load when the hand part 7 is lowered in the no-load state) to the most when the hand part 7 is raised in the state where the hand part 7 is gripping the object 8 to be transported (the hand part 7 is in the loaded state) Appropriate clearance cannot be maintained until a load is applied, and tooth skipping may occur.

Now, a configuration constituting the gist of each invention of the present application for accurately preventing tooth skipping will be described with reference to FIG. 4 (development schematic diagram).
First, since the timing pulley 14 is formed of a rigid body, the tooth pitch of the tooth portion 14a of the timing pulley 14 is constant, whereas the timing belt 5 is wound and fed out on the winding drum 14. Therefore, it is formed of an elastic body. Therefore, the maximum length is obtained when the transported object 8 is gripped and lifted with respect to the hand unit 7 to which the maximum tension is applied to the timing belt 5, and the hand unit 7 is lowered without gripping the transported object 8. Sometimes the minimum length.
As described above, it is desirable that the proper state of the meshed portions of the respective tooth portions 5a and 14a of the timing belt 5 and the timing pulley 14 when the timing belt 5 has the maximum length is in the relationship shown in FIG.
That is, the clearance formed between the tooth portion 14a of the timing pulley 14 and each tooth portion 5a of the timing pulley 14 at the center portion of the M portion where the timing belt 5 and the timing pulley 14 mesh between the pinch rollers 31 and 32. The dimension G1 is a normal dimension (clearance conventionally used), and the clearance G2 between the tooth part 14a of the timing pulley 14 formed at both ends and each tooth part 5a of the timing pulley 14 is maximized. .

On the other hand, it is desirable that the proper state of the meshing portions of the teeth 5a and 14a of the timing belt 5 and the timing pulley 14 when the timing belt 5 has the minimum length is in the relationship shown in FIG.
That is, the clearance formed between the tooth portion 14a of the timing pulley 14 and each tooth portion 5a of the timing pulley 14 at the center portion of the M portion where the timing belt 5 and the timing pulley 14 mesh between the pinch rollers 31 and 32. G1 has a normal size as in FIG. 4A, but the clearance G2 between the tooth portion 14a of the timing pulley 14 formed at both ends and each tooth portion 5a of the timing pulley 14 is minimized.
As shown in FIGS. 4 (A) and 4 (B), the method for optimizing the meshing portions of the tooth portions 5a and 14a of the timing belt 5 and the timing pulley 14 is as follows.
(1) The length of the meshing portions of the respective tooth portions 5a and 14a of the timing belt 5 and the timing pulley 14 (this length is M from FIG. 3).
(2) Elastic modulus of the timing belt 5 (Elongation per unit weight is E)
(3) Load load fluctuation amount W acting on the timing belt 5 (maximum load load−minimum load load)
And

In this case, the condition that the tooth skip does not occur is when the clearances G1 and G2 satisfy the following expressions 1 and 2.
0 ≦ G1 <0.4mm ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ (Formula 1)
M × E × W ≦ G2 <M × E × W + G1 (Expression 2)
In addition, if the clearances G1 and G2 are larger than necessary, the strength of the tooth portion is insufficient, and sufficient life resistance characteristics cannot be obtained. Become stable. The above (Formula 1) and (Formula 2) have a life resistance characteristic that the strength of the tooth portion is sufficient, and can ensure the stability of the lifting operation.
Theoretically, the clearance G1 is such that the load of the conveyed object 8 is not loaded in the state of FIG. 4B where the load of the conveyed object 8 is applied to the timing belt 5 (A). However, even if substantially the same, the above-described expressions 1 and 2 are hardly affected.

The number of timing belts 5 is optimal to obtain stable lifting / conveying of the object to be conveyed 8 and to simplify the drive mechanism of each timing belt 5, but in principle, the number of timing belts 5 is constituted by a plurality of timing belts. be able to.

In the dimension display diagram of FIG. 6 ((A) is a timing belt, (B) is a timing pulley)
L1: 0.35mm
L2: 1.1mm
L3: 0.85mm
L4: 2mm
L5: 1.1mm
L6: 0.85mm
L7: 0.7mm
H1: 0.65mm
H2: 0.5mm
D: 29.60mm
T: 0.65mm
It is.
In addition, when concrete numerical values are shown as the implementation data other than the elements of the above formulas 1 and 2,
G1: About 0.2mm
E: About 5.5 × 10 ⁻⁴ (mm / kg)
M: About 60mm
W: About 4Kg
Timing belt 5 width: about 25 mm
Teeth pitch of timing belt 5 and timing pulley 14: 2 mm
Possible length of the timing belt 5: 300 to 5,000 mm
It is.

In this embodiment, the length from the bottom of the drive unit 6 to the fixed part of the hand unit 7 of the timing belt 5 is 2500, and the maximum inclination angle is 0.28 degrees.
FIG. 7 is a graph showing the relationship between the timing belt load W (unit is kg) and the length L (unit is mm) in this embodiment.
According to this embodiment, it was confirmed that tooth skipping did not occur when the timing belt 5 and the tooth portions 5a and 14a of the timing pulley 14 were engaged.
When the width of the timing belt is in the range of 10 mm to 50 mm and the elongation E is in the range of 5.0 × 10 ⁻⁴ (mm / kg) to 5.0 × 10 ⁻⁶ (mm / kg), The appropriate value is 0.5 mm or less, preferably 0.2 mm or less, more preferably 0.1 mm or less.
The data described above shows one specific example of each invention of the present application, and does not limit the technical scope regulated by each claim.

It is a front view which shows the principal part structure of the cart for OHT to which this invention is applied. It is the schematic block diagram which planarly viewed the raising / lowering mechanism in the hand part of the cart for OHT to which this invention is applied. It is a block diagram which shows the application location of this invention. FIG. 2A is a developed schematic view of the meshed portion of each tooth portion of the timing belt and the timing pulley according to the present invention, where FIG. 1A is the timing belt tension is maximum (length is maximum), and FIG. It shows the situation when the belt tension is minimum (length is minimum). It is an expansion | deployment schematic diagram in the meshing site | part of each tooth | gear part of a timing belt and a timing pulley as a conventional means. FIG. 4 is a schematic diagram with dimensions of timing pulleys and timing belts in an embodiment of the present invention, where FIG. (A) is a dimension display of the timing belt and FIG. (B) is a dimension display of the timing pulley. It is a characteristic view which shows the relationship between the length of a timing belt and tension | tensile_strength (load) in the Example of this invention.

Explanation of symbols

1. 4. Cart for OHT Timing belt 5a. 5. Timing belt teeth Elevating mechanism7. Hand part 13. Winding drum 14. Timing pulley 14a. Timing pulley teeth 31, 32. Pinch rollers 33, 34. Guide roller

Claims (6)

A plurality of timing belts that form a belt shape, form a tooth portion along the longitudinal direction on one surface thereof, and support the transferred object gripping hand portion at the lower end portion;
For each timing belt, a timing pulley that meshes with the tooth portion and controls the lifting and lowering of the hand portion suspended by the timing belt;
Winding drums for winding or feeding out the corresponding timing belts by driving control of the timing pulleys;
In the lifting mechanism of the object to be transported in the carriage for the suspended lifting and lowering conveying device,
The tooth pitch of the timing belt in which the meshing state between the teeth of the timing belt and the timing pulley varies due to the elastic expansion and contraction of the timing belt depending on the presence or absence of a load corresponding to the presence or absence of the object to be conveyed. Even if there is a deviation in the tooth pitch of the timing pulley that does not cause elastic expansion and contraction, a meshing failure occurs by optimizing the tooth width dimension of the timing belt and the tooth width dimension of the timing pulley. And a mechanism for raising and lowering the object to be conveyed in the dolly type lifting and lowering conveyance device carriage, which is configured to maintain a predetermined mesh strength. Located in the vicinity of each of the timing pulleys, between the timing pulley and the conveyed object, between the timing pulley and the winding roller corresponding to the timing pulley, and the displacement of the timing belt in the width direction. The lifting mechanism of the to-be-conveyed object in the trolley | bogie for suspension type raising / lowering conveyance apparatuses of Claim 1 provided with the guide roller to prevent. A pinch roller is provided that presses a surface of the timing belt that does not form a tooth portion in one or a plurality of positions where each tooth portion of the timing pulley and the corresponding timing belt meshes with each other. The raising / lowering mechanism of the to-be-conveyed object in the cart for suspension type raising / lowering conveying apparatuses of Claim 1 or 2 to do. The number of timing belts is 4, The lifting mechanism for the object to be transported in the carriage for the suspended lifting / lowering transport apparatus according to any one of claims 1 to 3. The control means for keeping the tension of the timing belt between each timing pulley and the winding roller corresponding to the timing pulley constant within a predetermined range is provided. Lifting mechanism for the object to be transported in the trolley for the lifting and lowering transport apparatus. 6. The suspension type lifting and lowering conveying cart as set forth in claim 1, wherein each timing belt is provided with electric power for power generation to the hand section or electric wires necessary for supplying control signals. Lifting mechanism for the object to be transported.

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