JPH0544137Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The invention relates to an impression cylinder for an offset printing machine, which allows accurate printing without misalignment even when printing from the edge of paper, such as on business cards. It aims to make printing possible.

(Prior art) Conventional offset printing machines are equipped with reciprocating feed claws on both sides of the feed claws for pushing the trailing edge of the paper and feeding the leading edge between the blanket cylinder and the impression cylinder, and to prevent paper misalignment. A side gauge is provided to prevent the paper from shifting vertically, and a front gauge is provided between the reciprocating feed pawl and the impression cylinder to prevent paper from shifting vertically. The position of the leading edge of the ink transferred from the plate cylinder to the blanket cylinder) and the position of the leading edge of the paper to be printed are adjusted to an accuracy of ±5/100 mm or ±2/100 mm.

(Problem that the invention attempts to solve) However, for this type of offset printing press,
When performing high-speed printing by rotating the blanket cylinder and impression cylinder at high speed and continuously feeding paper, there are various problems such as paper slips, differences in paper size, and reciprocating feed for the blanket cylinder and impression cylinder. Due to the timing shift of the nails, etc., there is a slight shift in the relative position between the print starting point and the position of the leading end of the paper to be printed, and as a result, in the case of multi-color printing, printing misalignment may occur.

The present invention aims to eliminate the above-mentioned drawbacks of conventional offset printing presses and to provide an impression cylinder for an offset printing press that can perform high-speed printing without printing deviation.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the impression cylinder of the offset printing press according to the present invention has a movable pin movable up and down in the drum fixed to the rotating shaft. The movable pin is fitted with a spring that biases it upward, and the upper end of the movable pin is made to protrude from the drum surface through a through hole bored in the drum.

(Function) As shown in FIG. 5, when the paper 14 passes between the blanket cylinder 2 and the impression cylinder 3, the blanket cylinder 2 The printing starting point 12 and the leading edge position 1 of the paper 14 to be printed
The paper 14 is intermittently fed by a paper feeding mechanism that rotates at a slightly higher speed than the peripheral speed of the blanket cylinder 2 and impression cylinder 3, and It collides with the rear end of the movable pin 6 and is sent between the blanket cylinder 2 and the impression cylinder 3 while its traveling speed is braked by the movable pin 6.
At the same time, the leading edge of the paper 14 is held between the blanket cylinder 2 and the impression cylinder 3 and passes between them, and the paper 1
Printing is performed more accurately than at the predetermined position No. 4.

(Embodiment) Next, an embodiment of the present invention will be described with reference to the drawings. 1 is a plate cylinder, 2 is a blanket cylinder, and 3 is an impression cylinder in an offset printing machine. The impression cylinder 3 is composed of a rotating shaft 4 and a drum 5 fixed to the rotating shaft 4. Reference numeral 6 denotes a pair of left and right movable pins disposed within the drum 5. The lower end of the movable pin 6 is inserted into a transparent hole 7 drilled in the rotating shaft 4 so as to be able to rise and lower, and is supported on a coil spring 8 housed in the vertical hole 7, while the upper end is inserted into a transparent hole 7 drilled in the drum 5. The hole 9 is passed through and slightly protrudes from the surface. 10 is a cutout window formed in the drum 5 for mounting the movable pin 6. In addition, there are cases where there is only one movable pin 6,
Also, multiple units may be installed in parallel. Further, reference numeral 11 is ink transferred from the plate cylinder 1 to the blanket cylinder 2, 12 is a printing starting point, 13 is the position of the leading edge of the paper 14 where printing is to be performed, 15 and 16 are a feeding belt and a presser ball in the paper feeding mechanism, The presser ball 16 is rotatably held on a support plate 17. Reference numeral 18 denotes a feed roller disposed between the feed belt 15 and the impression cylinder 3, which always rotates at the same speed as the feed belt 15. Reference numeral 19 denotes a presser roller provided on the feed roller 18, and is pivotally supported at the tip of an arm 21 protruding from the arm shaft 20. Reference numerals 22 and 23 denote a fixed side gauge and a movable side gauge for preventing the paper 14 from shifting laterally, and 24 a front gauge for preventing the paper 14 from shifting vertically. 26 is a stripper.

Since one embodiment of the present invention has the above-described configuration, the printing starting point 12 on the blanket cylinder 2 side and the leading edge position 13 of the paper 14 where printing is to be performed are located at the same distance between the blanket cylinder 2 and the impression cylinder 3.
The relative positions of the movable pin 6 of the blanket cylinder 2 and the impression cylinder 3 are adjusted so that they coincide on the straight line l connecting the axes of the blanket cylinder 2 and
When the movable pin 6 of the impression cylinder 3 further moves and approaches the blanket cylinder 2 as shown in FIG. 3, the presser roller 19 descends and the front gauge 24 rises to feed out the paper 14, and after the paper 14 has passed, drive control is performed so that the presser roller 19 rises again and the front gauge 24 descends, so that the leading edge of the paper is always behind the movable pin 6. Since it is fed between the blanket cylinder 2 while being locked at the end, multicolor printing can be performed without causing any misalignment in the predetermined position.

(Effects) As described above, the impression cylinder of the offset printing press according to the present invention has the upper end of the movable pin protruding from the drum surface so as to be able to protrude and retract freely, and the leading end of the paper is always retained on the movable pin while being connected to the blanket cylinder. By adjusting the relative position between this movable pin and the print starting point of the blanket cylinder in advance, accurate printing can be performed without causing printing misalignment even on the leading edge of the paper. It is.

[Brief explanation of the drawing]

Fig. 1 is a partially longitudinal sectional front view showing an embodiment of the present invention, Fig. 2 is a sectional view taken along line A-A shown in Fig. 1, and Fig. 3 is a vertical sectional view showing the above embodiment in use. 4 is a plan view of the same in use, and FIG. 5 is an explanatory diagram showing the relative positional relationship between the impression cylinder and the rubber cylinder according to the present invention. 1... plate cylinder, 2... rubber cylinder, 3... impression cylinder, 4...
...Rotating shaft, 5...Drum, 6...Movable pin, 7...
...Vertical hole, 8...Spring, 9...Through hole, 12...
...Printing starting point, 13... Leading edge position to be printed, 14... Paper.

Claims (1)

[Scope of utility model registration request] A movable pin is arranged in a drum fixed to a rotating shaft so as to be movable up and down, and a spring is attached to the movable pin to bias it upward. An impression cylinder of an offset printing machine characterized by a protruding cylinder.