JP2002137527A - Stencil printing equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide stencil printing equipment equipped with a driving force transmitting means, which has a torque limiter for allowing to relieve an overloaded state when the overload is applied to a main motor and, at the same time, can keep a paper feeding position constant. SOLUTION: In the stencil printing equipment equipped with the driving force transmitting means 53 having a plate cylinder 33, a plate cylinder driving means 35 for rotatingly driving the plate cylinder 33 and a belt or a chain for transmitting a driving force sent from the plate cylinder driving means 35 to the plate cylinder 33, a torque limiter 36, which relieves the overloaded state when the plate cylinder driving means is subjected to the overloaded state, is provided in the driving force transmitting means 53 and, at the same time, the reduction ratio of the rotational frequency of the plate cylinder 33 to that of the plate cylinder driving means 35 is set to be an integer multiple.

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. 4 and 5, a main motor 2 for rotating and driving a plate cylinder (not shown) is attached to a rear side plate of the housing 1 via a bracket 3. The main motor 2 has a motor section 2a for the sake of increasing the output torque in order to rotate the plate cylinder.
A motor with a speed reducer having a speed reducer unit 2b is used.

Here, the structure of the main motor 2 will be briefly described. As shown in FIG. 6, a motor part 2a and a reduction gear part 2b constituting the main motor 2 are provided with a plurality of screws 2
i. A rotatable motor shaft 2c is provided inside the motor portion 2a, and a gear portion 2d is formed at the tip thereof. An output shaft 2e is rotatably supported by a plurality of bearings 2f and 2g inside the reduction gear unit 2b, and a plastic gear 2h meshing with a gear 2d is integrally attached to the output shaft 2e. 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. The reason for using the plastic gear 2h is that the use of a metal gear causes various problems such as deterioration of durability due to insufficient surface pressure, high processing cost, and increase in noise.

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. It is rotatably supported by a bracket 6 attached to the housing 1. A gear 7 is attached to an end of the output shaft 2e protruding from the bracket 6.
The gear 7 meshes with the gear 8 supported by the bracket 6 to transmit the driving force to other parts. Two tension pulleys 9 and 10 and a paper ejection timing pulley 11 (see FIG. 7) 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. A timing belt 13 is stretched over the timing pulley 4 and the discharge timing pulley 11, and the timing belt 13 is stretched over a large-diameter timing pulley 15 fixed to a drive shaft 14, and
Is transmitted to the plate cylinder via the drive shaft 14, and the plate cylinder rotates. The driving force is also transmitted via the timing pulley 15 to an impression cylinder (not shown) provided to be able to contact and separate from the plate cylinder.

In the stencil printing apparatus having such a 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. Will be. At this time, since the plate cylinder or impression cylinder tries to rotate by forcibly pushing away these sheets, the main motor 2 instantaneously outputs the maximum torque. This torque acts on the plate cylinder or impression cylinder, and then the timing pulley 15 It acts on the speed reducer 2b of the main motor 2 via the pulley 4. However, since this drive mechanism does not have a mechanism for releasing such a sudden torque, when a sudden torque is applied, the plastic gear 2h of the reduction gear unit 2b having the weakest strength is damaged, and There was a problem that the motor 2 had to be replaced. 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. Depending on the timing, the plastic gear 2h may be broken before the plastic gear 2h is broken. There is also. 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 when an abnormal current flows through the motor due to a sudden torque acting on the motor when the plate cylinder and the impression cylinder are locked, and stopping 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. Therefore, a technique has been proposed in which a torque limiter for releasing the overload state of the main motor in the driving force transmission means is proposed.
According to this technology, when a sudden torque is generated, the torque limiter slides to protect the plate cylinder driving mechanism, and to perform inexpensive and quick recovery without requiring expensive parts replacement or long repair work. Thus, cost reduction and improvement of work efficiency can be achieved at the same time.

[0007]

FIG. 8 shows an example of a driving force transmitting means using the above-described torque limiter. In addition,
The torque limiter used here is used in place of the timing pulley 4 described above, and the other main configuration is based on the configuration described above. Output shaft 2 of main motor 2
As shown in FIGS. 8 and 9, a torque limiter 16 is attached in the middle of e, and a gear 19 is attached to an end of the output shaft 2e via a bearing 17 and a shield sleeve 18. As shown in FIGS. 8 and 10, the shield sleeve 18 is rotatably supported via a bearing 21 on a bearing holder 20 attached to the bracket 6, and has one side attached to the bracket 6 of the bearing holder 20. A belt adjustment plate 24 that rotatably supports the gear 22 and the timing pulley 23 provided integrally with the gear 22 is attached to the other opposing side surface. The belt adjustment plate 24 is swingably attached to the bearing holder 20, and a tension spring 25 is attached between the bearing holder 20 and the belt adjustment plate 24. The gear 22 is in mesh with the gear 19, and a timing belt 27 is stretched between the timing pulley 23 and a timing pulley 26 rotatably supported by the housing 1, and the rotational force is transmitted to other parts. Has communicated. Among the above-described configurations, the timing belt 13,
The timing pulley 15, the torque limiter 16, and the like constitute a driving force transmitting means 28.

The torque limiter 16 is mainly composed of an inner ring 29, an outer ring 30, two springs 31 and the like as shown in FIG. The inner ring 29 has a boss 29a, a body 29b, a sliding portion 29c, and a groove 29d. A hole 29e into which the output shaft 2e can be fitted is formed in the center of the inner ring 29, and the inner ring 29 is connected to the output shaft 2e in the boss 29a.
Taps 29f for set screws for fixing the screw at two positions are formed at a relative angle of 90 degrees. Each spring 31 is provided on the outer peripheral surface of the body portion 29b, and the outer ring 30 is provided on the sliding portion 29c.
Are attached, and a C retaining ring 32 is attached to the groove 29d.

Each of the springs 31 is wound so that the inner diameter thereof is slightly smaller than the outer diameter of the body portion 29b, and is pressed against the outer peripheral surface of the body portion 29b with a predetermined spring force. One end of each spring 31 is bent at a right angle to form a standing bent portion 31a. Each of the springs 31 fixes each of the bent portions 31a and fixes the output shaft 2e.
Are rotated so that the contact force on the outer peripheral surface of the body portion 29b is loosened when the is rotated.

The outer race 30 includes flange portions 30a and 30b,
It has a sliding portion 30c, a concave portion 30d, and an index 30e.
Each of the flange portions 30a and 30b is formed on both end surfaces of the outer ring 30. The flange portion 30a is formed to have a larger diameter than the flange portion 30b, and a plurality of flange portions 30a and 30b are provided for meshing with the timing belt. 30g of teeth
Are formed. A concave portion 30 d into which each spring 31 can be fitted is formed in the center of the outer race 30.
The standing bends 31a of the springs 31 are fitted into Od, respectively, so that the outer race 30 and the springs 31 do not relatively rotate. A sliding portion 30c is formed on the inner diameter of the flange 30b. The sliding portion 30c is formed to have a size that allows a loose fit to the sliding portion 29c, and the sliding portions 29c and 30c are in sliding contact with each other. Four taps 30f for attaching the shield sleeve 18 are formed on an end surface of the flange portion 30a, and an index 30e is formed on a part of the outer peripheral surface of the flange portion 30b. As shown in FIG. 12, the index 30e is set at the home position at a position inclined by 18 degrees from the vertical line when the plate cylinder (not shown) is stopped at the home position as shown in FIG. A notch 3a for adjusting 30e to the home position is formed. As shown in FIG. 10, a timing belt 13 is stretched over the tooth portion 30g, and the torque limiter 16 is drivingly connected to the timing pulley 15.

Here, an index 30e provided on the outer ring 30 is provided.
The function of will be described. The number of teeth of the tooth portion 30g of the torque limiter 16 used in this example is set to 20, and the number of teeth of the timing pulley 15 is set to 50, respectively.
The reduction ratio between the torque limiter 16 and the timing pulley 15 is set to 2.5. The number of teeth and the reduction ratio are determined based on the strength of the teeth, the total load, the size of the motor, the output torque of the motor, and cannot be easily changed. Also, the reduction ratio is not usually an integer ratio in order to avoid the same teeth from hitting each other.

Since the reduction ratio is 2.5 as described above,
The position of the bent portion 31a of each spring 31 provided in the torque limiter 16 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. When the printing pressure is started, the printing cylinder is in a position where the printing cylinder is suddenly pressed against the plate cylinder to apply the printing pressure.
Is the position where the maximum torque acts on the torque limiter 16 when the torque fluctuation of the maximum becomes largest. Further, it is considered that the sliding portion 30c of the outer ring 30 indicated by a broken line in the drawing is deformed as illustrated by being pushed upward by the tension F of the timing belt 13 in the drawing.

In the configuration shown in FIGS. 1A and 1B, since the tension F and the torque T both act in the vertical direction and do not act in the horizontal direction, the state shown in FIG. There is not much difference between 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, in the state shown in the diagram (c), since the acting positions of the tension F and the torque T are far apart, the outer ring 3
0 tends to rotate in the same direction as the direction in which the torque T acts, and the position becomes unstable. On the other hand, in the state shown in FIG. 30 is difficult to rotate because it is pressed by the tension F. This difference causes a problem that the supply position of the sheet to the impression cylinder varies every time the plate cylinder rotates.

In order to examine the variation of the sheet supply position, as shown in FIG. 14, a point P1 near the start position of sheet feeding from the pair of registration rollers and a point P2 near the start position of closing the sheet clamper of the impression cylinder. The time required for the impression cylinder to rotate until the angle θ was measured several times using a time interval analyzer. When the position of the upright bent portion 31a of the spring 31 is shown in FIGS. 13C and 13D, the variation of the impression cylinder rotation time is as shown in FIG. Variations in the impression cylinder rotation time in the case of FIG. 13 (a) and FIG. 13 (b) are shown in FIG. As is clear from the figure,
In FIG. 15, two peaks of the time variation appear and the width of the variation is large, whereas in FIG. 16, only one peak of the time variation and the width thereof are small, so that the position of the standing bent portion 31 a is specified. It has been found that this makes it possible to suppress variations in the paper supply position with respect to the impression cylinder. Therefore, using the index 30e, the position of the upright bent portion 31a is determined so as to be the position shown in FIGS. 13A and 13B where the variation of the sheet supply position is the smallest.

However, the standing bend 3
Even if the positioning of 1a is performed, the bent portion 31 is formed every one rotation.
Since the position a is shifted by 180 degrees, the variation in the paper supply position may converge within a certain range, but may deviate from the allowable value when performing accurate printing. Further, it is apparent from FIG. 13C that the sliding portion 30c, which is a hole in which the inner ring 29 and the outer ring 30 are fitted, is also easily deformed, and the larger the gap, the greater the variation in the paper supply position. It is. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-described problems, and to provide a driving force capable of maintaining a paper supply position while having a torque limiter and allowing a main motor to be overloaded when overloaded. An object of the present invention is to provide a stencil printing apparatus provided with a transmission means.

[0016]

According to the first aspect of the present invention,
A plate cylinder, plate cylinder driving means for driving the plate cylinder to rotate, and driving force transmitting means having a belt or a chain for transmitting a driving force from the plate cylinder driving means to the plate cylinder; The transmission means is a stencil printing machine having a torque limiter for releasing the overprinted state of the plate cylinder driving unit when the plate cylinder driving unit is overloaded, wherein a reduction ratio of the rotation number of the plate cylinder to the rotation number of the plate cylinder driving unit is reduced. It is characterized by being an integral multiple.

According to a second aspect of the present invention, in the stencil printing apparatus of the first aspect, the torque limiter further comprises:
An inner ring and an outer ring provided around the inner ring and a spring interposed between the inner ring and the outer ring, wherein a part of the outer ring is press-fitted into a part of the inner ring. I do.

According to a third aspect of the present invention, in the stencil printing apparatus of the second aspect, at least one of the inner ring and the outer ring is made of resin.

According to a fourth aspect of the present invention, there is provided the stencil printing apparatus according to the first, second or third aspect, further comprising an impression cylinder which is provided so as to be able to freely contact and separate from the plate cylinder. Is rotationally driven by the driving force from the driving force transmitting means.

[0020]

FIG. 1 is a schematic view showing a main part of a stencil printing apparatus employing an 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 33 denotes a plate cylinder, and reference numeral 34 denotes an impression cylinder. The main motor 35 as the plate cylinder driving means is configured in the same manner as the main motor 2, and a torque limiter 36 is mounted in the middle of the output shaft 35e as shown in FIGS. A gear 19 is attached to the end via a bearing 17 and a shield sleeve 18. The timing belt 13 is wrapped around the torque limiter 36, and the timing belt 13 is wrapped around a timing pulley 37 having the same function as the discharge pulley 11 and the timing pulley 15. A predetermined tension is applied.

A small-diameter gear 38 is integrally provided coaxially with the timing pulley 37. The gear 38 is provided on a shaft 39a (FIG. 4) of a bracket 39 which is swingably supported coaxially with the drive shaft 14. (See FIG. 1). Gear 40 is coaxial with gear 40.
A gear 41 having a smaller diameter than that of the gear 41 is integrally provided, and the gear 41 is engaged with a gear 42 rotatably supported by the drive shaft 14 (see FIG. 4). A timing pulley 43 having a larger diameter than the gear 42 is integrally mounted on the same axis of the gear 42, and a timing belt 44 is wound around the timing pulley 43. The timing belt 44 is also wound around a timing pulley 46 attached to a support shaft 45 (see also FIG. 4) supported by a side plate 57 (see FIG. 4), and the rotational driving force of the main motor 35 is applied to the support shaft 45. Is transmitted to a gear 47 provided integrally with the timing pulley 46.

In the vicinity of the gear 47, an impression cylinder drive shaft 48 rotatably supported by the side plate 57 and supporting the impression cylinder 34 is provided, and a gear 49 meshing with the gear 47 is provided at an end thereof.
Is attached. Further, a gear 50 meshing with the gear 47 is provided at a position opposed to the arrangement position of the gear 49 via the gear 47. The gear 50 is attached to an end of a support shaft 51 rotatably supported on a side plate (not shown) of the housing 1. The gear 50 is for applying a predetermined printing pressure to the impression cylinder 34. Two printing pressure cams 52 are attached.

With the above configuration, when the main motor 35 is driven to rotate and the torque limiter 36 is rotated counterclockwise in FIG. 1, the timing pulley 37 drivingly connected to the torque limiter 36 by the timing belt 13 rotates. As a result, the plate cylinder 33 is driven to rotate counterclockwise. A gear 40 meshed with a gear 38 rotating integrally with the timing pulley 37, a gear 42 meshed with a gear 41 rotating integrally with the gear 40, a gear 42
The impression cylinder 34 is driven by the timing pulley 43 shown in FIG. 1 via a timing pulley 46 which is driven and connected by a timing belt 44 and a timing pulley 43 which rotates integrally with the timing pulley 43, and a gear 49 which meshes with a gear 47 which rotates integrally with the timing pulley 46. It is driven to rotate in the circumferential direction. Of these configurations,
The timing belt 13, the torque limiter 36, the timing pulley 37, the respective gears 38, 40, 41, 42, the respective timing pulleys 43, 46, the respective gears 47, 49, etc. constitute a driving force transmitting means 53.

As shown in FIG. 3, the torque limiter 36 mainly includes an inner ring 54, an outer ring 55, two springs 56, and the like. The metal inner ring 54 includes a boss portion 54a, a body portion 54b, and a sliding portion 54 similarly to the inner ring 29 described above.
c, a groove 54d, a hole 54e, and two taps 54f. Each spring 56 is provided on the outer peripheral surface of the body 54b,
The outer ring 55 is mounted on the sliding portion 54c, and the groove 5
The C retaining ring 32 is attached to 4d. Standing bending part 5
The spring 56 having 6a is formed in the same manner as the spring 31, and is mounted on the outer peripheral surface of the body 54b in the same manner as the spring 31.

The outer ring 55 includes flange portions 55a, 55b,
It has a sliding portion 55c, a concave portion 55d, and an index 55e.
Each of the flange portions 55a and 55b has the same configuration as the above-described flange portions 30a and 30b of the outer race 30, and a plurality of tooth portions 55g are formed between the flange portions 55a and 55b. A concave portion 55d similar to the concave portion 30d is formed at the center of the outer ring 55, and a sliding portion 55c is formed at the inner diameter of the flange portion 55b. The sliding portion 55c is the sliding portion 54
It is formed in a size that fits tightly with c,
The sliding portions 54c and 55c are pressed against each other. The pressing force of each of the sliding portions 54c and 55c is set to be sufficiently smaller than the spring force of each spring 56. Four taps 55f for attaching the shield sleeve 18 and three spigot portions 55h that fit into the notches 18a (see FIG. 2) formed in the shield sleeve 18 are formed on the end surface of the flange portion 55a. The indicator 5 similar to the indicator 30e is provided on a part of the outer peripheral surface of the flange portion 55b.
5e are formed. By forming the spigot portion 55h, the positioning of the shield sleeve 18 is ensured, and the strength of the resin outer ring 55 can be increased.

The torque limiter 3 used in this embodiment
The number of teeth of the tooth portion 55g of No. 6 is 22, the timing pulley 3
7, the number of teeth is set to 44, and the reduction ratio between the torque limiter 36 and the timing pulley 37 is 2.0.
Is set to The main motor 35 is selected as a motor that generates an output torque and a linear velocity that match the number of teeth and the reduction ratio. Thus, the reduction ratio is 2.
Since it is 0, the position of the upright bent portion 56a of each spring 56 provided in the torque limiter 36 is always the same every rotation. As a result, the working position relationship between the tension F and the torque T is always in the same state, and it is possible to prevent a problem that the sheet supply position to the impression cylinder varies every rotation. At this time, as the initial position of the index 55e, the position shown in FIG. 13 (a) or (b) is desirable. Further, since the sliding portions 54c and 55c are fitted so as to be tightly fitted, the amount of deformation of the sliding portion 30c (the sliding portion 55c in this embodiment) in FIG. 13 can be reduced. Thus, more stable paper supply can be performed. With the configuration of the present embodiment, the state shown in FIG. 16 could be maintained as the sheet supply position to the impression cylinder.

In the above-described embodiment, the torque limiter 36 is attached to the output shaft 35e of the main motor 35. However, the torque limiter 36 is located at another position of the driving force transmitting means 53, for example, the timing pulley 37, each gear 38,
40, 41, 42, each timing pulley 43, 46,
It may be attached to each gear 47, 49 and the like. In the above embodiment, the inner race 54 made of metal and the outer race 5 made of resin are used.
5, the torque limiter 36 is used. At least one of the inner ring and the outer ring may be made of resin. It is desirable to embed a member (for example, graphite or the like) that reduces the coefficient of friction so that each member does not wear abnormally during rotation by pressure.

[0028]

According to the present invention, since the driving force transmitting means has a torque limiter and the reduction ratio of the rotational speed of the plate cylinder to the rotational speed of the plate cylinder driving means is an integral multiple, the thick paper or the multi-feed paper can be used. When the plate cylinder driving means outputs high torque due to jams, etc., the torque limiter releases the load associated with the high torque output, preventing damage to the driving force transmitting means or plate cylinder driving means, reducing costs and printing efficiency. Can be achieved at the same time, and good printed matter can be obtained by keeping the paper supply position at a fixed position.

[Brief description of the drawings]

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

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

3A is a left side view, FIG. 3B is a front sectional view, and FIG. 3C is a right side view of the torque limiter used in the embodiment of the present invention.

FIG. 4 is an exploded perspective view showing a plate cylinder driving mechanism of a conventional stencil printing apparatus.

FIG. 5 is a cross-sectional view around a main motor of a conventional stencil printing apparatus.

FIG. 6 is a partial sectional view of a main motor of a conventional stencil printing apparatus.

FIG. 7 is a schematic diagram illustrating a driving force transmission unit of a conventional stencil printing apparatus.

FIG. 8 is a cross-sectional view around a main motor of a stencil printing apparatus including a driving force transmitting unit having a torque limiter.

FIG. 9 is a schematic diagram showing an assembled state of a torque limiter to a main motor in the stencil printing machine shown in FIG.

FIG. 10 is a schematic perspective view showing a driving force transmitting means of the stencil printing machine shown in FIG.

11A is a left side view of the torque limiter used in the stencil printing machine shown in FIG. 8, FIG. 11B is a front sectional view, and FIG.

FIG. 12 is a schematic diagram for explaining an index provided in a torque limiter.

FIG. 13 is a schematic diagram for explaining an external force acting on a torque limiter.

14 is a schematic diagram for explaining measurement of a sheet supply position to an impression cylinder in the stencil printing apparatus shown in FIG.

FIG. 15 is a chart showing variations in the sheet supply position with respect to the impression cylinder in the states shown in FIGS. 13 (c) and 13 (d).

FIG. 16 is a chart showing variations in the sheet supply position with respect to the impression cylinder in the states shown in FIGS. 13 (a) and 13 (b).

[Explanation of symbols]

 33 plate cylinder 34 impression cylinder 35 plate cylinder driving means (main motor) 36 torque limiter 53 driving force transmitting means 54 inner ring 55 outer ring 56 spring

Claims (4)

[Claims] An image forming apparatus includes: a plate cylinder; plate cylinder driving means for driving the plate cylinder to rotate; and driving force transmitting means having a belt or a chain for transmitting a driving force from the plate cylinder driving means to the plate cylinder. The driving force transmitting means is a stencil printing machine having a torque limiter for releasing the overprinted state of the plate cylinder driving means when the plate cylinder driving means is overloaded, wherein the rotation of the plate cylinder with respect to the rotation speed of the plate cylinder driving means is provided. A stencil printing machine characterized in that the number reduction ratio is an integer multiple. 2. The torque limiter has an inner ring, an outer ring provided around the inner ring, and a spring interposed between the inner ring and the outer ring, and a part of the outer ring is part of the inner ring. 2. The stencil printing machine according to claim 1, wherein the stencil printing machine is press-fitted. 3. The stencil printing machine according to claim 2, wherein at least one of said inner ring and said outer ring is made of resin. 4. The apparatus according to claim 1, further comprising an impression cylinder provided so as to be able to freely contact and separate from said plate cylinder, wherein said impression cylinder is driven to rotate by a driving force from said driving force transmitting means. The stencil printing apparatus according to claim 2 or 3.