JP2965413B2 - Stencil printing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stencil printing machine,
Specifically, it relates to the printing pressure applying means.

[0002]

2. Description of the Related Art There is a stencil printing apparatus which performs printing by pressing a printing sheet against a cylindrical plate cylinder around which a stencil sheet made on a stencil is wound by a pressing means. In such a stencil printing apparatus, a stencil holder for holding the leading end of the stencil paper is provided on the cylindrical outer peripheral surface of the plate cylinder.

The stencil holder has a structure protruding radially outward from the cylindrical outer peripheral surface of the plate cylinder, so that the plate cylinder rotates once in synchronization with the rotation of the printing drum in order to dodge the stencil holder. Every time, it is necessary to reciprocate the press roller as the press-contact means rapidly in the direction perpendicular to the rotation center axis.

[0004] The reciprocating motion of the press roller is performed with a large acceleration, so that a large impact or vibration is applied to the entire printing apparatus to cause noise, and wrinkles may be generated on the stencil sheet. These become worse as the pressing force of the press roller against the plate cylinder is larger.

In a stencil printing machine, when the printing environment such as the printing speed, room temperature, and humidity changes, the printing density is affected, and the ink does not bleed on the paper or the ink does not transfer properly on the paper. May not be able to obtain a perfect image.

[0006] These problems, that is, factors affecting print density include the amount of ink applied to the ink roller and the pressing force of the ink roller or press roller to the plate cylinder. Means for reducing the change in density due to the printing speed and the environment can be considered.

Among these factors, when adjusting the printing density by changing the amount of ink applied to the ink roller, the minute distance between the ink roller and the doctor roller may be adjusted. Must be very small in units of 1/100 mm, and the ink rollers and doctor rollers must be adjusted to have uniform intervals along their respective longitudinal directions, and the adjustment requires skill. It is extremely difficult for the user to adjust this.

When the printing density is adjusted by changing the pressing force of the ink roller on the plate cylinder, the pressing force can be changed by adjusting an eccentric cam or the like. It is necessary to adjust the left and right eccentric cams and the like so as to uniformly apply the pressing force in consideration of the unevenness, and the operation is extremely difficult.

Further, when adjusting the printing apparatus by changing the press pressure of the press roller on the plate cylinder, the position of the spring hook of the spring for setting the press pressure is adjusted, or the spring is adjusted by adjusting the screw. It is relatively simple, such as changing the press force by changing the return force, but this must also be adjusted in consideration of the parallelism of the press roller, and it is difficult for the user to adjust this. .

[0010] In addition, when the print density changes due to factors such as temperature change and print speed change, there is a problem that the user cannot adjust the print density by himself.

At present, the degree of change in print density due to a change in temperature or a change in printing speed is reduced by considerably increasing the pressing force of the press roller against the plate cylinder. Each time the press roller is reciprocated rapidly in the direction perpendicular to the center axis of its rotation in synchronism with the rotation of the plate cylinder and misses each time, collision noise and vibrations are generated, and office It is harsh when used inside.

In order to solve these problems, there has been proposed a stencil printing apparatus in which the printing density is adjusted by adjusting the pressing force of the press roller against the plate cylinder by an input operation from an operation panel (Japanese Patent Application Laid-Open No. H11-157686). JP-A-62-127276,
See JP-A-2-151473.

For example, in the technique disclosed in Japanese Patent Application Laid-Open No. 2-151473, a pressing force of a press roller against a plate cylinder is given by a spring pressure, and the spring pressure is applied to print density setting information set by print density setting means. The print density is adjusted by adjusting the print density.

For example, as compared with normal (normal temperature or normal speed printing), the printing pressure is reduced at high temperature or low speed printing, and increased at low temperature or high speed printing.

[0015]

As described above, the pressing force of the press roller is adjusted in accordance with a change in temperature or a change in printing speed. However, in order to perform this method effectively, the range of the printing pressure must be adjusted. You have to set it high.

That is, at low temperatures or high-speed printing, good printing density cannot be obtained unless the printing pressure is considerably increased. Further, even at a high temperature or a low-speed printing where the printing density is relatively high as compared with the above-mentioned conditions, a good printing density cannot be obtained without applying a certain large printing pressure.

The reason why a large printing pressure is required is considered as follows. In other words, at the time of printing, the ink is transferred from the plate cylinder to the paper through the opening of the plate cylinder through the nip between the press roller and the nip between the press roller and the printing paper. It is necessary to give the ink energy to flow and energy to adhere the ink to the paper surface.

On the other hand, if the printing environment changes, the energy required to make the fluid flow change. For example, at low temperatures, the viscosity of the ink increases, requiring a large amount of energy.
Also, as the printing speed increases, the time for the paper to pass between the nips decreases, and the time for applying energy to the ink decreases.

As a result, only a small amount of energy can be given, and it is difficult for the ink to flow or transfer. Therefore, if the printing pressure is increased, a large amount of energy can be given to the ink even in a short time, so that it is considered that there is an effect of reducing the change in the print density.

For this reason, in the prior art, the printing pressure has to be adjusted under set conditions in a high printing pressure range, and as a result, vibration and noise are generated.

Accordingly, an object of the present invention is to provide a stencil printing apparatus which can obtain a good printing state while eliminating the problems of vibration and noise.

[0022]

Means for Solving the Problems To achieve the above object, the present invention provides: Two press rollers, an elastic endless belt stretched between these two rollers, and a pressing means for pressing the printing paper against a cylindrical plate cylinder around which a stencil sheet made on the outer periphery is wound. And a belt press roller provided with

(2). (1) a connecting means in which two press rollers are connected so as to swing in the plate cylinder rotating direction;
An arrangement may be provided in which an adjusting means for changing the distance between the shafts of the roller is provided.

(3). In (2), an information setting means for setting print density information and printing speed information is provided, and an adjusting means is operated in accordance with the information to appropriately change the contact distance between the plate cylinder and the paper and the pressing force. It is a target.

[0025]

Since a belt press roller having an endless belt having elasticity as a main element is used in place of the conventional press roller, the nip width with the plate cylinder becomes longer, and the time required for the paper to pass between the nips (ink The time required for the ink to flow and transfer) becomes longer, a large amount of energy can be applied to the ink between the nip with the printing drum even at a low printing pressure, and a good image can be obtained even at a low printing pressure.

Further, the nip distance and the belt tension (the apparent hardness of the rollers) are adjusted by changing the distance between the axes of the two press rollers supporting the endless belt, thereby making it possible to adjust the print density.

[0027]

FIG. 1 shows a stencil printing machine 1 according to the present invention.
Has a stencil clamping mechanism 10 on the outer peripheral surface and an ink supply means 11 on the inner side.

In FIG. 1, a porous plate-shaped cylinder 12, a belt press roller 4, a paper feed table 14, a paper feed roller 15, and a belt type forcibly driven in a clockwise direction. A stencil making machine 2 for thermally stencil making a stencil sheet 19 housed in a roll by a paper discharging device 16, a thermal head 17 and a platen roller 18, and a stencil cutting cutter 2
0, and a plate discharging device 3 for separating used base paper from the plate cylinder 12 and storing it.

The printing paper P on the paper feed table 14 is
5, the sheet is sequentially fed one by one, an image is formed between the plate cylinder 12 and the belt press roller 4 which is a main part of the present invention, and then separated from the plate cylinder 12 by the separation claw 13, and the forced paper ejection device The sheet is conveyed at 16 and is stacked on the sheet discharge table 21.

Further, as shown in FIG. 1, the plate cylinder 12 is rotatably supported around its own central axis 22 by a structure not shown. The plate cylinder 12 is configured to have a porous structure and has a clamp mechanism 10 on an outer peripheral portion. The clamp device 10 is configured to cut a stencil sheet (indicated by reference numeral 23 in FIG. 2) cut from a stencil sheet 19. One end is intermittently locked.

That is, the clamp mechanism 10 is provided with the plate cylinder 12
And a movable clamp piece 26 supported by a shaft 25 extending along the axial direction of the plate cylinder 12 and the like. Have.

The movable clamp piece 26 is rotated by approximately 180 ° in a counterclockwise direction in the drawing from a clamp position when the movable clamp piece 26 is attracted to the permanent magnet 24 and closed by a mechanism (not shown). It is configured to be rotationally driven between two positions of the fully opened unclamping position.

The plate cylinder 12 is rotated intermittently or continuously in a clockwise direction in FIG. 1 by a driving device (not shown). Further, an ink supply unit 11 for printing is provided in the cylinder of the plate cylinder 12, and the ink supply unit 11 is configured such that an outer peripheral surface of an ink roller 28 constituting the ink supply unit 11 contacts an inner peripheral surface of the plate cylinder 12. It is arranged to be. The ink roller 28 is rotated around a shaft 27.

Further, a doctor roller 29 is provided so as to extend along the roller generatrix at a predetermined gap from the outer peripheral surface of the ink roller 28, and the ink roller 28 rotates the plate cylinder 12. The printing ink in the ink reservoir 30 is supplied to the inner peripheral surface of the plate cylinder 12 by being rotationally driven in the same direction as the plate cylinder in synchronization with the printing cylinder.

That is, in FIG.
Is passed through the gap between the ink roller 28 and the doctor roller 29 with the rotation of the ink roller 28, and at that time the ink is measured to form an ink layer having a uniform thickness on the outer peripheral surface of the ink roller 28. Form.

The ink layer is supplied to the inner peripheral surface of the plate cylinder 12 with the rotation of the ink roller 28, and flows through the mesh screen 31 and the stencil sheet 23 wound on the outer peripheral surface of the plate cylinder. , For printing.

Referring to FIG. 3, the structure of the belt press roller 4 and its peripheral portion will be described. Reference numeral 5 denotes a connecting means for applying a motion to the belt press roller 4 to press the printing paper P against the plate cylinder 12.

The connecting means 5 comprises an arm element 33, a shaft 3
4, a lever 35, an elastic spring 36 and the like. The belt press roller 4 is attached to one end of the arm element 33. The shaft 34 is pivotally attached to a side plate (not shown), and is fixed integrally with the other end of the arm element 33.

As for the lever 35, one end thereof is connected to the shaft 3
4 are integrally fixed. A spring 36 is hung on the other end of the lever 35, and the force of the spring 36
The arm element 33 and the lever 35 are integrally urged to rotate about the shaft 34 in the clockwise direction in FIG.

The rotation of the arm element 33, the lever 35, and the like due to the urging force is prevented by the cam follower provided at the other end of the lever 35 abutting on the cam 37. The cam 37 is driven by a mechanism (not shown) by the plate cylinder 1.
The belt 37 is rotated in synchronism with the rotation of the roller 2. By controlling the cam 37, the belt press roller 4 escapes every time the clamp mechanism 10 arrives during the rotation operation of the plate cylinder 12, thereby avoiding interference.

The belt press roller 4 comprises the following elements: a press roller 38a, a press roller 38b, an endless rubber belt 48 stretched between these rollers, and the like. 12 has a function of forming an image by pressing the outer peripheral surface of the image forming apparatus 12.

Next, a description will be given of adjusting means for making the distance between the rollers between the shafts variable. A first arm element 33 rotatably supports a press roller 38a with a shaft 39.
And a second arm element 33b that rotatably supports the press roller 38b with the shaft 40. An endless belt 48 is hung between these press rollers.

A support terminal 43 is provided on the first arm element 33a.
a, 43b are implanted. On the other hand, the second arm element 33b is formed with long slot-like guide grooves 42a, 42b for adjusting the tension of the belt, and the support grooves are formed in the guide grooves. By the engagement of the terminals, the direction and the amount of movement of the second arm element 33b are regulated with respect to the first arm element 33a, and the second arm element 33b is reciprocated.

The lower part of the first arm element 33a is bent into an L-shape to form a guide rail 41. The guide rail 41 is supported by engaging the second arm element 33b with the guide rail 41. It assists the guidance function. By moving the second arm element 33b with respect to the first arm element 33a, the tension of the endless belt 48 can be adjusted.

The means for this movement will be described. A rack 47 is formed on the first arm 33b , and a gear 46 meshes with the rack 47. This gear 46 is connected to the shaft 3 implanted in the first arm element 33a.
9 is rotatably mounted.

The gear 46 meshes with the worm 45. The worm 45 is attached to a shaft of a pulse motor 44 fixed to the first arm element 33a, so that the second arm element 33b moves forward and backward according to the forward or reverse rotation of the pulse motor 44. The tension (the surface hardness of the belt) of the belt 48 is adjusted.

By adjusting the tension, the pressing force of the belt press roller 4 against the plate cylinder 12 and the contact distance (nip width) between the plate cylinder 12 and the belt press roller 4 can be adjusted. This adjustment is based on the print density information at that time, as described later.

Therefore, a configuration in which the second arm element 33b is slidable relative to the first arm element 33a, and a configuration including a rack, gears, a worm, a pulse motor, and the like constitute an adjusting means.

Next, a process for operating the adjusting means based on print density information and print speed information will be described. FIG. 4 shows an operation panel 50 as an example of information setting means for setting print density information and print speed information.

When the number-of-prints setting information is input by the ten keys 50a of the operation panel 50, the printing speed is input by the printing speed setting key 50b, and the printing density information is input by the printing density setting key 50c. It is stored and stored in each area of a storage device not shown.

The operation will be described below with reference to the flowchart of FIG. The storage of the setting information is performed in steps 100, 101, 1
02. These pieces of stored information will be one of the conditions for the printing process.

When the predetermined print processing information is set as described above, the current ink temperature is detected by a temperature sensor (not shown) that detects the temperature of the ink, and the current ink temperature is stored in each area of the storage device. (Step 10
3).

Next, when the plate making start key 50e is depressed (step 104), the stencil used last time for printing and wound around the plate cylinder 12 based on a command from a control device (not shown). The base paper 23 is released from the clamped state, peeled off from the outer peripheral surface of the plate cylinder 12 by the plate discharging device 3, and discarded in the plate discharging box 49 (step 10).
5).

The stencil sheet 23 made by the plate making apparatus 2
Is clamped by a clamp mechanism 10, and the plate cylinder 12 is driven to rotate clockwise in FIG.
The stencil sheet 23 is wound around the outer peripheral surface of the plate cylinder 12 (step 106).

In the next step 107, when it is confirmed that the print start key 50d is pressed, in a step 108, together with the print number information setting information, the print speed setting information and the print density setting information stored in the storage device, The printing process is started based on the ink temperature information (step 109).

In this printing process, the center distance between the press rollers 38a and 38b is adjusted so that the printing process of the printing density set in accordance with the printing speed and the ink temperature is performed. The tension of the belt 48, the contact distance between the plate cylinder 12 and the belt, and the pressing force are controlled.

That is, a control device (not shown) constituted by a microprocessor or the like and connected to the storage device
Thus, the printing speed and the ink temperature are comprehensively determined so as to satisfy the printing density of the printing density setting information stored in the storage device, and the number of pulses to be supplied to the pulse motor 44 is determined.

For example, the print density setting key 50 shown in FIG.
Press d to increase the print density or press the print speed setting key 5
When the printing speed is set to a higher direction by setting the number of pulses to 0, the number of pulses supplied to the pulse motor 44 also increases correspondingly.
Pressing force and contact distance to the print head increase, and print density increases (see FIG. 6).

Alternatively, when the print density is set to a lower direction or the printing speed is set to a lower direction, the number of pulses supplied to the pulse motor 44 decreases, and as a result, the belt press roller 4 is pressed against the plate cylinder 12. The force and contact distance are reduced (see FIG. 7).

Next, in step 110, the control device determines whether or not the number of printed sheets P for which printing has been completed has reached the set number of prints. 50 print density setting keys 50
It is confirmed that the print density or the print speed has not been changed by the operation of the print speed setting key 50b or c (step 111), and the next print is performed under the same print conditions as the previous time.

If the print density or the print speed has been changed, the print density setting information or print speed setting information stored in the storage device is changed to the changed information in step 112.

Accordingly, in the subsequent printing process, the number of pulses supplied to the pulse motor 44 is controlled by the content determined according to the changed print density setting information or the printing speed setting information, and Plate cylinder 12 of roller 4
The pressing force and contact distance to the contact are changed.

Thereafter, each time the print density or the print speed is changed by operating the print density setting key 50c or the printing speed setting key 50b of the operation panel 50, the above processing is performed.

As described above, the belt press roller according to the present embodiment is configured with a belt, so that the distance between the outer peripheral surface of the plate cylinder and the printing paper can be lengthened, as in a conventional stencil printing apparatus. Printing can be performed with a very small pressing force as compared with pressing the outer peripheral surface of the plate cylinder at the time of printing with one press roller.

As a result, collision noise and vibration generated when the belt press roller collides with the plate cylinder are remarkably reduced.
At the same time, since the load fluctuation at the swinging part of the belt press roller is small, the stress applied to the drive system of the plate cylinder is small, and the durability of the apparatus is improved.

A means for connecting two press rollers reciprocally in the plate cylinder rotation direction to adjust the distance between the axes and a means for setting printing density information, printing speed information, and ink temperature information are provided. The nip width between the plate cylinder and the belt press roller and the pressing force can be changed as appropriate in accordance with this information. The print density can be adjusted by adjusting the nip width, pressing force, and the like to eliminate the change in print density due to the influence of printing speed and environment (ink temperature).

[0067]

According to the present invention, it is possible to provide a stencil printing apparatus capable of obtaining a good printing state while eliminating the problems of vibration and noise.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a stencil printing apparatus according to the present invention.

FIG. 2 is a detailed explanatory view of an ink roller unit.

FIG. 3 is an explanatory diagram of a belt press roller.

FIG. 4 is a front view of an operation panel.

FIG. 5 is a flowchart illustrating a printing process.

FIG. 6 is a diagram illustrating a state in which a contact distance of a belt press roller to a plate cylinder is adjusted to be long.

FIG. 7 is a diagram illustrating a state in which the contact distance of the belt press roller to the plate cylinder is adjusted to be short.

[Explanation of symbols]

 4 Belt press roller 38a Press roller 38b Press roller 48 Endless belt

Claims (3)

(57) [Claims] 1. A stencil printing apparatus for performing printing by pressing a printing sheet against a cylindrical plate cylinder around which a stencil sheet made on a stencil is wound by a press-contact means, wherein the press-contact means comprises two press rollers. And a belt press roller provided with an elastic endless belt stretched between these two rollers. 2. A stencil device according to claim 1, further comprising a connecting means for connecting two press rollers so as to be swingable in a plate cylinder rotating direction, and an adjusting means for changing a distance between the rollers. A stencil printing machine characterized by the following. 3. A stencil printing machine according to claim 2, further comprising information setting means for setting print density information and printing speed information, and operating the adjusting means in accordance with the information to make contact between the plate cylinder and the paper. A stencil printing machine characterized by appropriately changing the distance and the pressing force.