EP3632684B1

EP3632684B1 - Printing mechanism of offset printing machine

Info

Publication number: EP3632684B1
Application number: EP18857136.8A
Authority: EP
Inventors: Wenchun CHE; Jinhua Yu; Xiangfu MENG
Original assignee: Zhejiang Weigang Technology Co Ltd
Current assignee: Zhejiang Weigang Technology Co Ltd
Priority date: 2017-09-14
Filing date: 2018-05-31
Publication date: 2021-11-24
Anticipated expiration: 2038-05-31
Also published as: EP3632684A4; CN107639923A; WO2019052228A1; DK3632684T3; ES2905166T3; EP3632684A1

Description

Technical Field

The present invention relates to a printing device, and more specifically to a printing mechanism of an offset printing machine.

Background

A lithographic offset printing machine is a printing machine in which when printing, a printed graphic is printed onto the rubber blanket of a blanket roller from the printing plate of a plate roller, and then transferred onto the paper from the blanket roller. The printing mechanism of the offset printing machine includes a plate roller, a blanket roller and an impression roller, where the three rollers cooperate with each other to complete paper printing.
A web offset printing machine is an offset printing machine for printing a web material, whose existing printing method is an intermittent offset printing method. Regardless of the change in the printed pattern length of a printed matter, the outer diameters of the plate roller and the blanket roller are fixed. When the printed pattern length of the printed matter is changed, the maximum printable circumference of the plate roller is unequal to the printed pattern length of the printed matter. If the printed pattern length is less than the maximum printable length of the plate roller, a relatively large blank (an area without printed pattern) is generated between adjacent two printed patterns on the printed paper, which causes a large waste and thus is disadvantageous for printing. In order to achieve a more ideal printing, a notch is designed on each of the plate roller and the blanket roller, and the two notches are set in synchronization correspondingly. When the notch on the blanket roller faces the impression roller, the printed matter (such as paper and film) is retracted under a driving force of a front and rear traction to eliminate the printing blank on the paper, while printing is performed when running in a forward direction, forming a back-and-forth intermittent printing method. This printing method has the following obvious drawbacks in printing: on one hand, the printing speed is hard to get increased, affecting printing efficiency; and on the other hand, the tension applied to the printed matter is not stable, which is prone to cause tensile deformation, affecting the printing accuracy and printing effect. Relevant prior art documents include DE 10 2007 017097 A1 , which discloses a printing cylinder changing device for printing-length-adjustable printing units in a full-rotation printing press according to the preamble of claim 1.
The device includes a printing cylinder sleeve that can be exchanged for adaptation to the printing length and which can be laterally slid on the printing cylinder core and can be connected in a rotationally fixed manner.
WO 2004/103707 A1 discloses a printing cylinder support unit for use in an offset printing press. The support unit includes a frame and at least three bearing devices. Each bearing device includes a set of support means that is intended to support a printing cylinder such that it can rotate about its centre axis.
US 2014/102324 A1 discloses a variable cutoff printing press that includes a plate cylinder, a plate cylinder support removably supporting the plate cylinder, a blanket cylinder, a blanket cylinder support removably supporting the blanket, an impression cylinder, an impression cylinder support and actuators for moving the blanket cylinder support toward and away from the plate cylinder support to accommodate different blanket cylinder sizes. The blanket cylinder support has an arm that includes a roller cam and a sliding element driven for movement by an actuator.
US 8 850 975 B2 discloses a variable cutoff printing unit and method that include a plate cylinder, a plate cylinder support removably supporting the plate cylinder, a blanket cylinder, a blanket cylinder support removably supporting the blanket cylinder, a frame, the plate cylinder support and the blanket cylinder support being coupled to the frame, a sliding element coupled to the blanket cylinder support for moving the blanket cylinder support toward and away from the plate cylinder support, and a stopping device for stopping movement of the sliding element to limit the movement of the blanket cylinder toward and away from the plate cylinder to a defined range.
US 2015/336373 A1 discloses variable-format offset printing units in which each of two supporting members of the intermediate cylinder is connected to the respective supporting member of the impression cylinder by a respective linear actuation device that includes a first element and a second element that are movable relative to each other along a direction of relative movement. The first element of each linear actuation device is hinged to a respective supporting member of the intermediate cylinder and the second element of each linear actuation device is hinged to a respective supporting member of the impression cylinder.
EP 2 388 140 A2 discloses a processing machine with at least one printing unit that includes at least three drivable cylinders where a first printing form cylinder 1 has a stationary axle position and is stored interchangeably or exchangeably in this axis position in a first bearing. A rocker in a stationary hinge is mounted at one end and at the other end of the rocker, a second bearing is provided for receiving a further, replaceable or replaceable transfer cylinder.

Summary

In view of the technical problems existing in the art described in the background, the technical problem to be solved in the present invention is to provide a printing mechanism of an offset printing machine capable of replacing plate rollers and blanket rollers of different outer diameters, so that the outer surface circumferences (i.e., the roller surfaces) of the plate rollers and the blanket rollers correspond to a printed pattern length of a printed matter without a retraction during printing, and the material feeding of the printed matter is stable, thereby promoting the printing speed and the printing efficiency, and improving the printing accuracy and printing effect.
In order to solve the above technical problem, the present invention provides a printing mechanism of an offset printing machine according to claim 1. Further preferred embodiments of the invention are defined in the dependent claims.
The present invention has the following advantages: the printing mechanism of the offset printing machine can replace plate rollers and the blanket rollers of different outer diameters; printing of different printing pattern lengths is realized; it is ensured that print patterns on roll paper are continuous between units (there are almost no blanks); the utilization of the roll paper is improved and the retraction of the roll paper is avoided, which effectively improves the printing speed and printing efficiency, and does not affect the paper feeding. The paper tension is stable; which improves the printing accuracy. Thus, the present invention possesses prominent substantive features and remarkable improvements over the prior art.

Brief Description of the Drawings

The details and working principles of the implementations and embodiments of the present invention are described below with reference to the accompanying drawings.

FIG. 1 is a schematic view of a structure of the present invention showing the swinging arm of the invention in the adjusted positions.
FIG. 2 is a cross-sectional view on the A-A direction of FIG. 1.
FIG. 3 is a cross-sectional view on the B-B direction of FIG. 1.

Detailed Description of the Embodiments

Referring to the accompanying drawings, a printing mechanism of an offset printing machine in the present embodiment includes the plate roller 1, the blanket roller 4 and the impression roller 2, and paper printing is realized by the cooperation of the three rollers. The plate roller 1 is sleeved on the plate shaft 16, and the blanket roller sleeve 4 is sleeved on a blanket shaft 21. Therefore, plate rollers and blanket rollers of different outer diameters can be replaced on the shafts. A positioning pin and a notch are provided between the shaft and the roller to position and match with each other, thereby ensuring that there is no relative sliding between the shaft and the roller. Alternatively, an elastic layer is provided in an inner hole of the roller and a gas hole is provided on the shaft. The gas hole is controlled to blow gas by a gas source and a gas valve. When the roller is sleeved on the shaft, the gas is blown by the gas hole to open up the elastic layer in the inner hole of the roller. After the roller is sleeved in place, the gas hole is stopped to blow the gas, and the elastic layer in the inner hole of the roller shrinks and clasps on the shaft.
The impression roller 2 is rotatably provided on a machine frame, and the impression roller is configured to be driven by the motor 19 (e.g., a servo motor) to rotate. The plate roller 1 is correspondingly matched with the blanket roller 4, which means that the roller surface of the blanket roller 4 is correspondingly matched with a pattern unit on the plate roller 1 in N times, where N is a positive integer, preferably 1 or 2 for a convenience of the blanket of the printing pattern. For example, when the plate roller 1 has a same or slightly different size (generally referring to the outer diameter) with the blanket roller 4, the roller surface of the blanket roller 4 can be just correspondingly matched with one pattern unit on the plate roller 1 (the relationship of 1 time); or, the roller surface (i.e., the outer surface circumference) of the roller 4 corresponds to two pattern units on the plate roller (the relationship of 2 times). Referring to the accompanying drawings, in the present embodiment, the relationship of 1 time is used, and the plate roller has the same size with the blanket roller.
The plate roller 1 and the blanket roller 4 maintain contact and roll against each other. The pattern on the plate roller is transferred onto the blanket roller. The plate shaft 16 is rotatably provided on the machine frame 3. The plate shaft 16 is configured to be driven by the motor 13 (e.g., a servo motor) to rotate, and drives the plate roller on the plate shaft to rotate. The blanket shaft 21 is provided to rotate around its axis. The blanket shaft 21 is configured to be driven by the motor 20 (e.g., a servo motor) to rotate, and drives the blanket roller 4 on the blanket shaft 21 to rotate. A position of the axis of the blanket shaft 21 is adjustable on the blanket shaft running trajectory 40. When blanket rollers of different outer diameters are selected and used, the position of the axis of the blanket shaft 21 on the blanket running trajectory 40 is adjusted, so that each of the blanket rollers 4 of different outer diameters can maintain contact and rolls against the impression roller 2. The blanket roller is correspondingly matched with the plate roller in outer diameter, and they maintain contact and roll against each other while the blanket roller and the impression roller maintain contact and roll against each other. Therefore, when printing patterns of different lengths, the corresponding plate roller and blanket roller can be replaced. Then, the position of the axis of the blanket shaft is adjusted, so that the blanket roller and the plate roller maintain contact and roll against each other, the blanket roller and the impression roller maintain contact and roll against each other, and the printing patterns on the roll paper are continuous between the units. The utilization of the roll paper is improved and the roll paper does not need to be retracted, which effectively improves the printing speed and efficiency. Moreover, the paper tension and the material feeding are stable.
A curved groove is provided on the machine frame 3. For example, the curved groove is provided on a wall plate of the machine frame 3. The curved groove forms the blanket running trajectory. The blanket shaft 21 of the blanket roller is provided on the curved groove by a mounting base. The blanket shaft of the blanket roller is rotatably provided on the mounting base. The position of the mounting base on the curved groove is adjustable. The position of the axis of the blanket shaft on the blanket running trajectory is adjusted by adjusting the position of the mounting base on the curved groove.
The blanket running trajectory 40 is configured to be a circular arc trajectory. blanket rollers of three different outer diameters are optionally taken. There are correspondingly three axis positions of the blanket shafts on the circular arc trajectory. The three axis positions correspond to the mounting positions of the blanket rollers of the three different outer diameters. Each of the blanket rollers maintains contact and rolls against (ideally, maintained to be externally tangent against) the impression roller at the three axis positions. The three axis positions can be just enough to determine the circular arc trajectory, thereby ensuring that the blanket rollers of three sizes can maintain contact and roll against the plate roller and the impression roller on the circular arc trajectory. At other positions near each of the three axis positions on the circular arc trajectory, blanket rollers of other outer diameters (other than the three optional outer diameters) can also maintain contact and roll against the impression roller and the plate roller by applying different pressures. The three different outer diameters may be a maximum outer diameter, a minimum outer diameter, and an intermediate outer diameter, respectively, such as 245 mm, 145 mm, and 200 mm.
A position of the impression roller 2 on the machine frame 3 is adjustable in the radial direction, which means, that the position of the impression roller 2 on the machine frame can be changed and adjusted in the radial direction. At an initial position of the impression roller, each of the blanket rollers at the three axis positions maintains contact and rolls against the impression roller at the initial position, where the initial position refers to a position before the impression roller is adjusted. Adjustment may be performed so that a central rotating shaft of the impression roller 2 is provided on the eccentric shaft sleeve 23. The position of the impression roller in the radial direction is adjusted by adjusting the position of the eccentric shaft sleeve on the machine frame. When the blanket running trajectory 40 is configured to be a circular arc trajectory, it is difficult to ensure that the blanket rollers on the blanket shafts at positions other than the three axis positions of the circular arc trajectory simultaneously maintain contact and roll against the plate roller and the impression roller. By adjusting the position of the impression roller in the radial direction, it can be ensured that the respective rollers contact and roll against each other.
The circular arc trajectory may be in the form of a circular arc groove provided on the machine frame. In the present embodiment, the form of the swinging arms 5, 24 is used, specifically as follows: the blanket shaft 21 of the blanket roller is rotatably provided on the swinging arms 5, 24 (left and right swinging arms, respectively); the blanket shaft 21 is rotated around its axis; the swinging arms 5, 24 are pivotable on the machine frame 3; pivoting of the swinging arms 5, 24 forms a circular arc trajectory, namely, the blanket running trajectory 40; and the position of the axis of the blanket shaft 21 on the circular arc trajectory is adjusted by pivoting.
The circular arc trajectory formed by using the form of the swinging arms also has three axis positions which can be just enough to determine a circular arc trajectory. On the circular arc trajectory, it is ensured that the blanket rollers of at least three sizes can maintain contact and roll against (ideally, maintained to be externally tangent against) the plate roller and the impression roller, achieving adjustment of the at least three sizes. The blanket rollers at the vicinity of the three sizes can also maintain contact and roll against each other by pressure adjustment. However, the blanket rollers on the blanket shaft at other positions on the circular arc trajectory are difficult to simultaneously maintain contact and roll against the plate roller and the impression roller. In order to ensure that the respective rollers contact and roll against each other, in addition to adjusting the position of the impression roller on the machine frame in the radial direction, the circular arc trajectory is also adjusted. The adjustment may further change the size of the printing pressure between the rollers. According to the present invention, the swinging arms 5, 24 are provided to swing on the machine frame 3 by the swinging arm shaft 22. The position of the swinging arm shaft 22 on the machine frame 3 is adjustable in the radial direction and the position of the swinging arm shaft 22 on the machine frame can be changed in the radial direction. At an initial position of the swinging arm shaft 22, swinging arm each of the blanket rollers located at the three axis positions maintains contact and rolls against the impression roller, where the initial position refers to a position before the swinging arm shaft is adjusted. By adjusting the positions of the swinging arms in the radial direction, the position of the circular arc trajectory can be adjusted accordingly. The swinging arm shaft can be adjusted on the eccentric shaft sleeve, and the position of the swinging arm shaft in the radial direction is adjusted by adjusting the position of the eccentric shaft sleeve on the machine frame.
The swinging arms 5, 24 are driven by a driving device to reciprocate around the swinging arm shaft on the machine frame 3. The driving device may directly drive the swinging arms to swing by using a cylinder to top push the swinging arms or using a lead screw-equipped motor. In the present embodiment, preferably, the following structure is used: the driving device includes the pushing rod 6, the jacking rod 8, a cylinder transmission and a screw transmission. The cylinder transmission includes a cylinder. The screw transmission device includes the screw 11, a nut and the slider 9. The nut is provided on the slider 9. The screw 11 is driven by the power source 12 (such as a servo motor and a torque motor) for driving the nut to drive the slider 9 to move up and down on the machine frame. The guiding rail 7 is provided on the machine frame for the slider to move up and down. The pushing rod 6 is hinged on the swinging arm 5. The jacking rod 8 is hinged on the slider 9. The pushing rod and the jacking rod are hinged to each other. The pushing rod is drivably connected to the cylinder, or the jacking rod is drivably connected to the cylinder, or a hinge point between the pushing rod and the jacking rod is drivably connected to the cylinder. The pushing rod and the jacking rod are driven to move by cooperating with the cylinder. In the present embodiment, when the driving device is in operation, the power source 12 drives the screw, and the screw 11 drives the nut to drive the slider 9 to move up and down on the machine frame. The slider drives the swinging arm to swing back and forth by cooperation with the jacking rod, the pushing rod and the air cylinder. After initially arriving in place, the power source stops driving the screw, and the cylinder communicates with an air source to pressurize against the swinging arm. By adjusting the pressure change of the cylinder, the pressure of maintaining the blanket roller on the swinging arm to contact and roll against the impression roller and the plate roller can be adjusted. When the slider of the screw transmission is locked on the machine frame by lifting the screw and the nut, the blanket roller can be prevented from jumping and shaking during printing, thereby avoiding the occurrence of the phenomenon of ink stick. The cylinder employs a double-stroke cylinder or double cylinders. The piston rod of the cylinder is hinged together with the pushing rod and the jacking rod. The cylinder is swingably provided on a cylinder base. The cylinder employing the double-stroke cylinder or double cylinders can perform a double-stroke operation. One small stroke may be set in the double stroke. When the swinging arm is swung in the small stroke, the blanket roller can be separated from the other two rollers for inspection or debugging. The double cylinders 25, 26 are used in the figure.
The machine frame 3 is provided with a plate roller replacement port. The first end cover 17 is provided on the plate roller replacement port. The bearing 18 matched with the plate shaft 16 is provided in the first end cover 17. The blanket roller replacement port 15 is provided on the machine frame 3. The swinging arm 5 is located on a side of the blanket roller replacement port 15, which is an outer side in the present embodiment, and obviously, may be provided on an inner side. The second end cover 27 is provided on the swinging arm 5, and the second end cover is provided on an end cover mounting port of the swinging arm. The bearing 10 matched with the blanket shaft 21is provided in the second end cover 27. A groove may further be provided on a wall plate for the movement of the blanket shaft on the swinging arm. In the present embodiment, the swinging arms 5 and 24 are provided on left and right sides of the wall plate of the machine frame, respectively. The plate roller replacement port and the blanket roller replacement port are both located on the right wall plate of the machine frame. An end cover mounting port for mounting the second end cover 27 is provided on the right side of the swinging arm 5. The operation of replacing the roller is described by taking the swinging arm as an example. When replacing the roller, the swinging arm swings to the position of the blanket roller replacement port, and the second end cover on the right swinging arm is removed from the blanket shaft. After the removal and separation, as long as the swinging arm swings to the position of the blanket roller replacement port again, the blanket roller on the blanket shaft can be replaced. After the replacement, the swinging arm swings to the blanket shaft so that the second end cover is reinstalled to match with the blanket shaft. In addition, the first end cover of the wall plate is opened, the plate roller is removed from the plate shaft for replacement at the plate roller replacement port, and the first end cover is reinstalled after the replacement.

Claims

A printing mechanism of an offset printing machine, comprising a plate roller (1), a blanket roller (4), and an impression roller (2), wherein, the plate roller (1) is sleeved on a plate shaft (16); the blanket roller (4) is sleeved on a blanket shaft (21); the impression roller (2) is rotatably provided on a machine frame (3); the plate roller (1) is correspondingly matched with the blanket roller (4) the plate roller (1) and the blanket roller (4) maintain contact and roll against each other; the plate shaft (16) is rotatably provided on a machine frame (3); the blanket shaft (21) is provided to rotate around an axis thereof; a position of the axis of the blanket shaft (21) is adjustable on a blanket shaft running trajectory (40); and when blanket rollers (4) of different outer diameters (a, b, c) are selected and used, the position of the axis of the blanket shaft (21) on the blanket shaft running trajectory (40) is adjusted, so that each of the blanket rollers (4) of the different outer diameters (a, b, c) maintains contact and rolls against the impression roller (2), wherein the blanket shaft running trajectory (40) is a circular arc trajectory; blanket rollers (4) with different outer diameters within a preset printing length; axes positions of the blanket shaft (21) are correspondingly provided on the circular arc trajectory; and each of the blanket rollers (4) at the axes positions maintains contact and rolls against the impression roller (2), wherein
the blanket shaft (21) is provided to rotate on swinging arms (5, 24); each of the swinging arms (5, 24) is swingably provided in the machine frame (3); and the circular arc trajectory of the blanket shaft running trajectory (40) is formed by swinging the swinging arms (5, 24), and the position of the axis of the blanket shaft (21) is adjustable on the circular arc trajectory, characterized in that each of the swinging arms (5, 24) is provided on the machine frame (3) to pivot at a swinging arm shaft (22) and a position of the swinging arms (5, 24) on the machine frame (3) is adjustable in a radial direction.
The printing mechanism of the offset printing machine of claim 1, characterized in that each of the swinging arms (5, 24) is driven by a driving device to reciprocate around the swinging arm shaft (22) on the machine frame (3); the driving device comprises a pushing rod (6), a jacking rod (8), a cylinder transmission and a screw transmission; the cylinder transmission comprises an air cylinder (25); the screw transmission comprises a screw (11), a nut and a slider (9); the nut is provided on the slider (9); the screw (11) is driven by a power source (12) for driving the nut to drive the slider (9) to move up and down on the machine frame (3); the pushing rod (6) is hinged on the swinging arm (5, 24); the jacking rod (8) is hinged on the slider (9); the pushing rod (6) and the jacking rod (8) are hinged to each other; and the pushing rod (6) or/and the jacking rod (8) are further drivably connected to the air cylinder (25).
The printing mechanism of the offset printing machine of claim 2, characterized in that the air cylinder (25) is a double-stroke cylinder or double cylinders; a piston rod of the cylinder is hinged together with the pushing rod (6) and the jacking rod (8); and the cylinder is swingably provided on a cylinder base.
The printing mechanism of the offset printing machine of claim 1, characterized in that a plate roller (1) replacement port is provided on the machine frame (3); a first end cover (17) is equipped on the plate roller replacement port; a bearing (18) matched with the plate shaft (16) is provided on the first end cover (17); a blanket roller replacement port (15) is provided on the machine frame (3); one of the swinging arms (5) is on an outer side or on an inner side of the blanket roller replacement port (15); a second end cover (27) is provided on said one swinging arm (5); the second end cover (27) is provided on an end cover mounting port of said one swinging arm (5); and a bearing matched with the blanket shaft (21) is provided in the second end cover (27).