JP2002127581A - Stencil printing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stencil printing apparatus equipped with a plate cylinder driving mechanism which is protected even when a sudden torque occurs and which can be restored inexpensively and quickly without necessitating replacement of an expensive component or long-time repair work. SOLUTION: In the stencil printing apparatus having a plate cylinder 16, a plate cylinder driving means 2 to drive the plate cylinder 16 to rotate and a driving force transmitting means 37 to transmit a driving force from the plate cylinder driving means 2 to the plate cylinder 16, an overload protection device 18 letting off a state of overload when the plate cylinder driving means 2 comes to this state is provided for the driving force transmitting means 37.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stencil printing apparatus having a plate cylinder and a plate cylinder driving means for driving the plate cylinder to rotate, and more particularly to a driving force transmitting means for transmitting a driving force from the plate cylinder driving means to the plate cylinder. Regarding the structure.

[0002]

2. Description of the Related Art Conventionally, digital thermosensitive stencil printing has been known as a simple printing method. This is achieved by bringing a thermal head in which fine heating elements are arranged in a line into contact with a heat-sensitive stencil master (hereinafter referred to as “master”) formed by laminating a thermoplastic resin film and a porous support. By conveying the master with a conveying means such as a platen roller while energizing in a pulsed manner according to the original image,
After a perforated image based on image information is made on the thermoplastic resin film of the master by hot-melt perforation, the perforated master is wound around a porous cylindrical plate cylinder, and printing paper is pressed by a pressing member such as a press roller. Is pressed against the outer peripheral surface of the plate cylinder to transfer ink oozed from the opening of the plate cylinder and the perforated portion of the master to the printing paper to obtain a print image. In this stencil printing apparatus, as shown in FIGS. 15 and 16, a main motor 2 for rotating and driving a plate cylinder (not shown) is mounted on a rear side plate of the housing 1 via a bracket 3. As the main motor 2, a motor with a reduction gear having a motor part 2a and a reduction gear part 2b is used in order to increase the output torque for rotating the plate cylinder.

Here, the structure of the main motor 2 will be briefly described. As shown in FIG. 17, the motor section 2a and the reduction gear section 2b that constitute the main motor 2 are integrated by a plurality of screws 2i. A rotatable motor shaft 2c is provided inside the motor portion 2a, and a gear portion 2d is formed at the tip thereof. Reduction gear unit 2b
, An output shaft 2e is rotatably supported by a plurality of bearings 2f and 2g.
Is integrally mounted with a plastic gear 2h that meshes with. With the above configuration, when a current flows in the motor section 2a, the motor shaft 2c rotates, and this rotational force is transmitted to the output shaft 2e via the gear section 2d and the plastic gear 2h. Here, the reason why the plastic gear 2h is used is that if a metal gear is used, various problems such as deterioration of durability due to insufficient surface pressure, high processing cost, and increase in noise occur.

A small-diameter timing pulley 4 is mounted in the middle of the output shaft 2e of the main motor 2 as shown in FIGS. 15, 16 and 18, and a portion near the end thereof is connected via a bearing 5. Bracket 6 attached to housing 1
It is supported rotatably. A gear 7 is attached to an end of the output shaft 2e protruding from the bracket 6, and the gear 7 meshes with a gear 8 supported by the bracket 6 to transmit a driving force to another portion. Two tension pulleys 9 and 10 and a paper ejection timing pulley 11 (see FIG. 18) are rotatably supported on the bracket 6, and the tension pulley 9 is swingable on the bracket 6 via the mounting plate 12. Attached to.
Timing pulley 4 and discharge timing pulley 1
1, a timing belt 13 is stretched over the timing belt 13. The timing belt 13 is stretched over a large-diameter timing pulley 15 fixed to a drive shaft 14, and the driving force of the main motor 2 is transmitted through the drive shaft 14. And transmitted to the plate cylinder to rotate the plate cylinder. The driving force is also transmitted via a timing pulley 15 to an impression cylinder (not shown) provided to be able to contact and separate from the plate cylinder.

[0005]

In the stencil printing apparatus having the above-described configuration, printing is performed using various types of paper. If a paper transport jam occurs during printing using thick paper or when double feeding occurs during printing, thick paper or multi-fed paper that has been overlapped due to multi-feeding is unlikely to deform, which hinders the rotational movement of the plate cylinder or impression cylinder. However, at this time, the plate cylinder or impression cylinder forcibly pushes away these sheets and tries to rotate, so that the main motor 2 instantaneously outputs the maximum torque. This torque acts on the plate cylinder or the impression cylinder, and then acts on the reduction gear section 2b of the main motor 2 via the timing pulley 15 and the timing pulley 4.

Since the above-mentioned drive mechanism does not have a mechanism for releasing such a sudden torque, the plastic gear 2h of the gear unit 2b, which is the weakest in strength, is damaged when a sudden torque is applied. However, there is a problem that the main motor 2 must be replaced. Also,
Although not shown, a plastic gear is often used also in a portion for transmitting the driving force from the timing pulley 15 to the impression cylinder.
The plastic gear may be damaged before h is damaged. Even in this case, repair on the user side is impossible, and there has been a problem that printing work is interrupted for a long time. When the thin paper is jammed alone, the paper is easily deformed, so that the locked state of the plate cylinder and the impression cylinder hardly occurs, and the gear is hardly damaged.

Further, there is a type having a function of detecting an abnormal current flowing through the motor when a plate cylinder or an impression cylinder is locked and a sudden torque acts on the motor to stop the operation of the motor. However, since the relationship between the generated current value and the torque is not accurate, the plastic gear 2h is damaged before the detection, and it is not possible to temporally cope with the instantaneous generation of high torque.

The present invention solves the above-mentioned problems, protects the plate cylinder driving mechanism even when a sudden torque is generated, and eliminates the need for expensive parts replacement or long-term repair work, thereby reducing the cost. Another object of the present invention is to provide a stencil printing apparatus having a plate cylinder driving mechanism capable of performing quick recovery.

[0009]

According to the first aspect of the present invention,
A stencil printing machine having a plate cylinder, plate cylinder driving means for rotating and driving the plate cylinder, and driving force transmitting means for transmitting a driving force from the plate cylinder driving means to the plate cylinder; Is characterized by having an overload protection device for releasing the plate cylinder driving means when it becomes overloaded.

According to a second aspect of the present invention, in the stencil printing apparatus according to the first aspect, the overload protection device further comprises a fixing member attached to a drive shaft of the plate cylinder driving means;
It is characterized by having a rotating member rotatably fitted to the fixing member, and a shear pin connecting the fixing member and the rotating member.

According to a third aspect of the present invention, in the stencil printing machine according to the second aspect, the rotating member has an extruding mechanism used for press-fitting or removing the shear pin. .

According to a fourth aspect of the present invention, in the stencil printing apparatus of the first aspect, the overload protection device further includes a torque limiter that idles when a load greater than a predetermined value acts. .

According to a fifth aspect of the present invention, in the stencil printing apparatus of the fourth aspect, the overload protection device further comprises a belt or a chain in the driving force transmitting means, and a rotation of the plate cylinder driving means. When the reduction ratio of the number of rotations of the plate cylinder to the number is not an integral multiple, an index indicating the position of the torque limiter is provided.

According to a sixth aspect of the present invention, in the stencil printing apparatus of the fifth aspect, the reduction ratio is a multiple of 0.5.

According to a seventh aspect of the present invention, in the stencil printing apparatus according to any one of the first to sixth aspects, the plate cylinder driving means is a motor with a speed reducer. I do.

[0016]

FIG. 1 is a schematic view of a main part of a stencil printing apparatus adopting a first embodiment of the present invention. In this embodiment, the same components as those shown in the related art are denoted by the same components, and detailed description thereof is omitted. In the figure, reference numeral 16 denotes a plate cylinder, and reference numeral 17 denotes an impression cylinder.
As shown in FIGS. 1 and 2, a torque transmitting member 18 as an overload protection device is mounted in the middle of the output shaft 2e of the main motor 2 as plate cylinder driving means.
A gear 20 having the same function as that of the gear 7 is attached to an end of the gear e via a bearing 19. Torque transmission member 18
, A timing belt 13 is wound around the timing belt 13. The timing belt 13 is wound around a timing pulley 11 and a timing pulley 15, and a predetermined tension is applied by the tension pulleys 9 and 10.

A small-diameter gear 21 is provided integrally on the same axis of the timing pulley 15, and this gear 21 meshes with a gear 23 rotatably supported by a bracket 22 supported by the housing 1. I have. A gear 24 having a smaller diameter than the gear 23 is integrally provided on the same axis as the gear 23, and the gear 24 is meshed with a gear 25 rotatably supported by the drive shaft 14 (see FIG. 15). A timing pulley 2 having a larger diameter than the gear 25 is coaxial with the gear 25.
The timing belt 28 is wound around the timing pulley 27.
The timing belt 28 is also wrapped around a timing pulley 30 attached to a support shaft 29 rotatably supported on a side plate (not shown) of the housing 1, and the rotational driving force of the main motor 2 is applied to the support shaft 29 by the timing pulley. The power is transmitted to a gear 31 provided integrally with the gear 30.

An impression cylinder drive shaft 32 rotatably supported by a side plate (not shown) of the housing 1 and supporting the impression cylinder 17 is provided near the gear 31. A meshing gear 33 is attached. Also, the gear 33
A gear 34 meshing with the gear 31 is provided at a position facing the arrangement position of the gear 31 via the gear 31. Gear 34
Is attached to an end of a support shaft 35 rotatably supported on a side plate (not shown) of the housing 1. The support shaft 35 has two pieces for applying a predetermined printing pressure to the impression cylinder 17. Is mounted.

With the above structure, when the main motor 2 is driven to rotate and the torque transmitting member 18 is rotated clockwise in FIG. 1, the timing pulley 15 drivingly connected to the torque transmitting member 18 by the timing belt 13. The plate cylinder 16 is driven to rotate clockwise by the rotation of. Also, a gear 23 meshed with a gear 21 rotating integrally with the timing pulley 15, a gear 25 meshed with a gear 24 rotating integrally with the gear 23, a timing pulley 27 rotating integrally with the gear 25, and the timing belt 2
The impression cylinder 17 is rotationally driven in a counterclockwise direction in FIG. 1 via a timing pulley 30 that is drivingly connected by the gear 8 and a gear 33 that meshes with a gear 31 that rotates integrally with the timing pulley 30. Among these components, the driving force transmitting means 37 is constituted by the timing belt 13, the timing pulley 15, the rotational force transmitting member 18, the respective gears 21, 23, 24, 25, the respective timing pulleys 27, 30, the respective gears 31, 33, and the like. It is configured.

The rotational force transmitting member 18 is shown in FIGS.
As shown in FIG. 7, the main part is composed of a fixing member 38, a rotating member 39, and a shear pin 40 described later. Fixing member 3
8, a boss 38a and a flange 3 as shown in FIG.
8b and a sliding portion 38c. A hole 38d, into which the output shaft 2e can be fitted, is formed in the center of the fixing member 38, and the boss 38a has a hole 2d formed toward the hole 38d.
The taps 38e at the locations are disposed such that the respective angles are 90 degrees. Two counterbore holes 38f are formed in the flange portion 38b, and a notch 38g for a retaining ring is formed near the end of the sliding portion 38c.

The rotating member 39 has a hole 39a at the center thereof which can be fitted to the sliding portion 38c, and is fitted to the fixing member 38 in such a manner that one side surface abuts against the flange portion 38b. A groove 39b is formed on one side of the rotating member 39, and a flange 39c protruding to the same height as the flange 38b is formed on the other side.
A plurality of teeth 39d for winding the timing belt 13 is formed on the outer peripheral surface except 9c. Further, on one side surface, each counterbore hole 38 formed in the flange portion 38b is provided.
Taps 39e are formed at positions corresponding to f.

The rotational force transmitting member 18 having the above configuration is
With the counterbore holes 38f and the taps 39e aligned, the fixing member 38 and the rotating member 39 are fitted together, and each member 3
The fitting holes 38h, 39 having the same diameter for fitting the shear pin 40 in a state where the screws 8 and 39 are fixed by two screws.
f is formed in the axial direction from the flange portion 38b by simultaneous processing. The second fitting portion 40 of the shear pin 40, which is larger in diameter than the fitting hole 38h and is described later, is provided at the flange portion 38b at a position facing the fitting hole 38h via the hole 38d.
A discharge hole 38i having a diameter larger than b is formed, and a hole 39g having a diameter larger than the fitting hole 39f penetrating the fitting hole 39f is formed in the other side surface of the rotating member 39. , Hole 3
9g is provided with a tap 39h. Each fitting hole 38
After the formation of h and 39f, the two screws fixing the members 38 and 39 are removed.

FIG. 5 shows the shear pin 40 inserted into each of the fitting holes 38h and 39f. The shear pin 40 is
First fitting portion 40a inserted into fitting hole 38h, fitting hole 3
9f, the second fitting portions 40b inserted into the respective fitting portions 40a,
It has a connecting portion 40c for connecting 40b. 1st fitting part 4
0a is a loose fit with respect to the fitting hole 38h,
The diameter of the second fitting portion 40b is set so that the second fitting portion 40b fits tightly into the fitting hole 39f. The connection part 40c has a constricted shape so that the connection part 40c is cut when a torque equal to or more than a predetermined shearing load is applied.

To assemble the rotational force transmitting member 18, first, the second fitting portion 4 of the shear pin 40 is inserted into the fitting hole 39f of the rotating member 39.
0b, and the rotating member 39 is fixed to the fixing member 38 in this state.
To fit. At this time, the first fitting portion 40a of the shear pin 40 is aligned with the fitting hole 38h of the fixing member 38, and when the members 38 and 39 are fitted, the first fitting portion 40a is fitted into the fitting hole 38h. Let it. Next, the retaining screw 41 shown in FIG.
Screw. The retaining screw 41 has a screw portion 41a formed with a screw 41c to be screwed into the tap 39h and a holding portion 41b formed to have a thickness capable of being fitted into the fitting hole 39f. Is formed with a hexagonal hole 41d into which a hexagonal wrench can be fitted. Screw 41 for retaining
Is formed slightly shorter than the depth of the hole 39g. After the retaining screw 41 is screwed into the tap 39h, the pan screw 42 (see FIG. 2) is screwed into the tap 39i formed near the tap 39h forming position of the rotating member 39. The formation position of the tap 39i is
At the time of screwing in 2, the head is set at a position to cover a part of the end face of the screw portion 41a. Finally, the E-retaining ring 43 (refer to FIG. 2) is fitted into the notch 38g, so that the torque transmitting member 1
8 (see FIG. 7), the rotational force transmitting member 18 has the output shaft 2e inserted into the hole 38d, and then two setscrews (not shown) are screwed into the respective taps 38e. 2 is assembled.

According to the stencil printing apparatus provided with the driving force transmitting means 37 having the rotational force transmitting member 18 described above, the main motor 2 is driven by a jam of thick paper or multi-feed paper.
When a high torque is output, the connecting portion 40c of the shear pin 40 is cut by a shear load corresponding to the high torque, whereby the fixed state of the fixing member 38 and the rotating member 39 is released, and the main motor 2 When only the attached fixing member 38 idles, the plastic gear 2h inside the main motor 2 or the driving force transmitting means 37
This can prevent the plastic gear provided on the vehicle from being damaged.

The on-site replacement of the cut shear pin 40 is performed in the following procedure. First, the torque transmitting member 18 is removed from the output shaft 2e, and the pan screw 42 and the E retaining ring 4 are removed.
After removing the fixing member 3, the fixing member 38 and the rotating member 39 are relatively rotated (the shear pin 40 is rotatable because the shear pin 40 is cut), and the shear pin 40 that is cut and remains in the fitting hole 39f is removed. Second fitting portion 40b and discharge hole 38i
And In this state, the retaining screw 41 is further screwed in, and the second fitting portion 40b is pushed out from the inside of the fitting hole 39f by the holding portion 41b.
As shown in FIG. 7, the discharge hole 38 having a larger diameter than the second fitting portion 40b.
The second fitting portion 40b can be discharged from i. The first of the shear pins 40 remaining in the fitting holes 38h
The fitting portion 40a has a fitting hole 38h having a diameter of the first fitting portion 40a.
It can be easily removed because it is smaller in diameter than
In the case where it is difficult to remove the connection portion 40c at the time of disconnection due to bites or the like of the connection portion 40c being bitten or the like, after the second fitting portion 40b is removed, the retaining screw 41 is used to remove the second fitting portion 40b, similarly to the second fitting portion 40b. It may be removed. In addition, the groove 39 is
Since b is formed, the fragments of the connection portion 40c are mainly stored in the groove portion 39b, and are configured to be hard to bite into other portions.

After the removal of the cut shear pin 40 is completed, a new shear pin 40 is mounted. The mounting of the new shear pin 40 is performed in a state where the fixing member 38 and the rotating member 39 are relatively rotated and the fitting holes 38h and 39f are aligned with each other on a straight line. In this state, when the shear pin 40 is inserted into the tap 39h as shown in FIG. 8 (b), the first fitting portion 40a is fitted into the fitting hole 39f.
8 is easily inserted to a position where it passes
As shown in (c), the retaining screw 41 is tapped 39h.
Is screwed into the second fitting portion 40b so that the fitting hole 3
The shear pin 40 can be easily inserted up to a position just before fitting to 9f. At this time, the first fitting portion 40a has entered the fitting hole 38h, and the fixed member 38 and the rotating member 39 are relatively positioned.

After the second fitting portion 40b is fitted into the fitting hole 39f, the shear pin 40 is pushed in by the thrust of the retaining screw 41, and the end surface of the screw portion 41a is rotated by the rotating member 39.
When the retaining screw 41 is screwed until it becomes flush with the other side surface, the mounting of the shear pin 40 is completed. After that, as shown in FIG.
Are fitted and the pan screw 42 is screwed into the tap 39i to complete the replacement operation of the shear pin 40. During this series of operations, the tap 39h and the retaining screw 4
1 constitutes an extruding mechanism 44.

As described above, by using the driving force transmitting means 37 provided with the torque transmitting member 18 according to the present invention,
Since the operation of replacing the shear pin 40 at the printing work site can be easily performed, the operation is not interrupted for a long time, and the plastic gear 2h inside the main motor 2 or the plastic gear provided on the driving force transmitting means 37 is used. As damage can be prevented,
It is possible to simultaneously reduce costs and improve printing efficiency.

FIG. 9 is a schematic view of a main part of a stencil printing apparatus employing a second embodiment of the present invention. The present embodiment is different from the first embodiment only in that the torque transmitting member 18 of the driving force transmitting means 37 is replaced with a torque limiter 45, and is different from the prior art and the first embodiment. The same components as those shown in the drawings are denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIGS. 9 and 10, a torque limiter 45 as an overload protection device is mounted in the middle of the output shaft 2e of the main motor 2, and a bearing 46 and a bearing 46 are provided at the end of the output shaft 2e. A gear 48 is attached via a shield sleeve 47. Shield sleeve 47
Is rotatably supported via a bearing 50 on a bearing holder 49 attached to the bracket 6 as shown in FIGS. 9 and 11, and faces one side of the bearing holder 49 attached to the bracket 6. A belt adjustment plate 53 that rotatably supports a gear 51 and a timing pulley 52 provided integrally with the gear 51 is attached to the other side surface. The belt adjustment plate 53 is swingably attached to the bearing holder 49,
A tension spring 54 is mounted between the bearing holder 49 and the belt adjustment plate 53. Gear 51 is gear 4
8 and the timing pulley 52
A timing belt 56 is stretched between a timing pulley 55 that is rotatably supported by the robot, and transmits a rotational force to other parts.

As shown in FIG. 12, the torque limiter 45 mainly comprises an inner ring 57, an outer ring 58, two springs 59 and the like. The inner ring 57 has a boss portion 57a, a body portion 57b, a sliding portion 57c, and a groove portion 57d. A hole 57e into which the output shaft 2e can be fitted is formed at the center of the inner ring 57, and a tap 57f for a set screw for fixing the output shaft 2e to the boss portion 57a is formed at a relative angle of 90 degrees. Two portions are formed. Each spring 59 is mounted on the outer peripheral surface of the body 57b. The outer ring 58 is provided on the sliding portion 57c.
Is attached, and a C retaining ring 60 is attached to the groove portion 57d.

Each of the springs 59 is wound so that its inner diameter is slightly smaller than the outer shape of the body 57b, and is pressed against the outer peripheral surface of the body 57b with a predetermined spring force. One end of each spring 59 is bent at a right angle to form a standing bent portion 59a. Each of the springs 59 fixes each of the bent portions 59a and fixes the output shaft 2e.
Are mounted in such a direction that the contact force on the outer peripheral surface of the body portion 57b is relaxed when is rotated.

The outer ring 58 includes flange portions 58a, 58b,
It has a sliding portion 58c, a concave portion 58d, and an index 58e.
The flange portions 58a and 58b are formed on both end surfaces of the outer ring 58. The flange portion 58a is formed to have a larger diameter than the flange portion 58b, and a plurality of flange portions 58a and 58b are provided for meshing with the timing belt. 58g of teeth
Are formed. A concave portion 58 d into which each spring 59 can be fitted is formed at the center of the outer race 58.
The upright bent portions 59a of the respective springs 59 are fitted into 8d, respectively, so that the outer race 58 and the respective springs 59 do not relatively rotate. A sliding portion 58c is formed on the inner diameter of the flange 58b, and the sliding portion 58c slides on the sliding portion 57c. Four taps 58f for attaching the shield sleeve 47 are formed on the end surface on the flange portion 58a side, and an index 58e is formed on a part of the outer peripheral surface of the flange portion 58b. The index 58e is
In the present embodiment, as shown in FIG. 13, the home position is set at a position inclined by 18 degrees from the vertical when the plate cylinder 16 is stopped at the home position, and the index 58e is attached to the bracket 3 by the home position. A notch 3a is formed in order to match with. As shown in FIG. 11, the timing belt 13 is stretched over the teeth 58g.

With the above arrangement, when the main motor 2 is operated and the plate cylinder 16 and the impression cylinder 17 are driven to rotate, when the external force acts on the plate cylinder 16 or the impression cylinder 17 and the rotation thereof is hindered, the main motor 2 generates a high torque. At this time, each spring 59 is loosened and separated from the body 57b, and only the inner ring 57 rotates together with the output shaft 2e, thereby preventing a load on the main motor 2 and preventing the main motor 2 from rotating. It is possible to prevent the plastic gear 2h inside the plastic gear 2 or the plastic gear provided in the driving force transmitting means 37 from being damaged, and it is possible to simultaneously reduce costs and improve printing efficiency.

Here, the reason why the index 58e is provided on the outer ring 58 will be described. The number of teeth of the tooth portion 58g of the torque limiter 45 used in the second embodiment is set to 20 and the number of teeth of the timing pulley 15 is set to 50, and the speed reduction between the torque limiter 45 and the timing pulley 15 is performed. The ratio is set to 2.5. These number of teeth and reduction ratio are set based on the strength and the like, and cannot be easily changed.

Since the reduction ratio is 2.5 as described above,
The position of the bent portion 59a of each spring 59 provided in the torque limiter 45 is shown in FIG.
And (b), or (c) and (d), the position is shifted by 180 degrees for each rotation. In the figure,
Symbol F indicates the direction of the force generated by the tension of the timing belt 13, and symbol T indicates the direction of the torque at the start of the printing pressure load. At the start of the printing pressure load, this is a position where the impression cylinder 17 is suddenly pressed against the plate cylinder 16 to apply the printing pressure, and a position where the maximum torque acts on the torque limiter 45 due to the largest torque fluctuation of the main motor 2. It is. Further, it is considered that the sliding portion 58c of the outer ring 58 indicated by the broken line in the figure is pushed upward in the figure by the tension F of the timing belt 13, and is deformed as shown in the figure.

From the above configuration, in the configurations shown in the diagrams (a) and (b), both the tension F and the torque T act in the vertical direction and do not act in the lateral direction. There is not much difference between the state shown in a) and the state shown in FIG. However, in the configuration shown in the split diagrams (c) and (d), the torque T acts in the left-right direction, and the acting direction is different from the tension F. Therefore, the distribution diagram (c)
In the state shown in FIG. 5, the outer ring 58 is likely to rotate in the direction in which the torque T is applied because the acting position of the tension F and the torque T are far apart, and the position becomes unstable, while the state shown in FIG. In this case, the operation positions of the tension F and the torque T are substantially the same, and the outer ring 58 is hardly rotated by being pressed by the tension F. Due to this difference, there has been a problem that the supply position of the sheet to the impression cylinder 17 varies every time the plate cylinder 16 rotates. From these facts, when the plate cylinder 16 occupies the home position, the position of the upright bent portion 59a can be set so as to be in the state shown in FIG. 14 (a) or (b). An index 58e and a notch 3a are provided for this position setting.

As a modification of each of the above embodiments, a tolerance ring (ISO9002) is fitted to the output shaft 2e instead of the torque transmitting member 18 or the torque limiter 45, and the timing pulley 4 is attached via the tolerance ring. The same operation and effect can be obtained as a configuration. Further, in each of the above embodiments and modifications, the rotational force transmitting member 18, the torque limiter 45, and the tolerance ring, which are overload protection devices, are attached to the output shaft 2e of the main motor 2, but the overload protection device is driven. It may be attached to other positions of the force transmitting means 37, for example, the timing pulley 15, the respective gears 21, 23, 24, 25, the respective timing pulleys 27, 30, the respective gears 31, 33, and the like.

[0040]

According to the present invention, since the driving force transmitting means has the overload protection device, when the plate cylinder driving means outputs a high torque due to a jam of thick paper or multi-feed paper or the like, an overload protection device is provided. The load protection device functions to release the load associated with the output of high torque, thereby preventing damage to the driving force transmitting means or the plate cylinder driving means, and simultaneously achieving cost reduction and improvement in printing efficiency. Can be.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a main part of a stencil printing apparatus employing a first embodiment of the present invention.

FIG. 2 is a cross-sectional view around a main motor showing a first embodiment of the present invention.

FIG. 3 is a side view of the rotational force transmitting member used in the first embodiment of the present invention.

FIG. 4 is a front sectional view of a rotational force transmitting member used in the first embodiment of the present invention.

FIG. 5 is a schematic diagram illustrating a shear pin used in the first embodiment of the present invention.

FIG. 6 is a schematic diagram illustrating a retaining screw used in the first embodiment of the present invention.

FIG. 7 is a side view showing an assembled state of the rotational force transmitting member used in the first embodiment of the present invention.

FIG. 8 is a schematic diagram illustrating replacement of a shear pin in a rotational force transmitting member used in the first embodiment of the present invention.

FIG. 9 is a cross-sectional view around a main motor showing a second embodiment of the present invention.

FIG. 10 is a schematic diagram showing an assembly of a torque limiter used in a second embodiment of the present invention.

FIG. 11 is a schematic perspective view showing a driving force transmitting means according to a second embodiment of the present invention.

FIG. 12 is (a) a left side view, (b) a front sectional view, and (c) a right side view of the torque limiter used in the second embodiment of the present invention.

FIG. 13 is a schematic diagram illustrating an index provided in a torque limiter used in a second embodiment of the present invention.

FIG. 14 is a schematic diagram for explaining an external force acting on a torque limiter used in a second embodiment of the present invention.

FIG. 15 is an exploded perspective view showing a plate cylinder driving mechanism of a conventional stencil printing apparatus.

FIG. 16 is a cross-sectional view around a main motor of a conventional stencil printing apparatus.

FIG. 17 is a partial sectional view of a main motor of a conventional stencil printing apparatus.

FIG. 18 is a schematic diagram illustrating a driving force transmission unit of a conventional stencil printing apparatus.

[Explanation of symbols]

 2 Plate Cylinder Driving Means (Main Motor) 16 Plate Cylinder 18 Overload Protection Device (Rotation Force Transmission Member) 37 Driving Force Transmission Means 38 Fixed Member 39 Rotating Member 40 Shear Pin 44 Extrusion Mechanism 45 Overload Protection Device (Torque Limiter) 58e index

Claims (7)

[Claims] 1. A stencil printing machine comprising: a plate cylinder; plate cylinder driving means for driving the plate cylinder to rotate; and driving force transmitting means for transmitting a driving force from the plate cylinder driving means to the plate cylinder. The stencil printing apparatus, wherein the driving force transmitting means includes an overload protection device that releases the overloaded state of the plate cylinder driving means. 2. The overload protection device according to claim 1, further comprising: a fixing member attached to a driving shaft of the plate cylinder driving means; a rotating member rotatably fitted to the fixing member; 2. A stencil printing machine according to claim 1, further comprising a shear pin for connecting the moving member. 3. The stencil printing apparatus according to claim 2, wherein said pivoting member has an extruding mechanism used for press-fitting or removing said shear pin. 4. The stencil printing apparatus according to claim 1, wherein the overload protection device includes a torque limiter that runs idle when a load greater than a predetermined value acts. 5. The overload protection device according to claim 1, wherein said driving force transmitting means has a belt or a chain, and a reduction ratio of a rotation speed of said plate cylinder to a rotation speed of said plate cylinder driving means is not an integral multiple. The stencil printing apparatus according to claim 4, further comprising an index indicating a position of the torque limiter. 6. The stencil printing apparatus according to claim 5, wherein said reduction ratio is a multiple of 0.5. 7. The stencil printing apparatus according to claim 1, wherein said plate cylinder driving means is a motor with a speed reducer.