JP3363820B2 - Method of attaching blanket to blanket cylinder and offset printing apparatus having the blanket - Google Patents

Description

Detailed Description of the Invention

[0001] The present invention is a method of attaching the order attach the blanket to the blanket cylinder of a printing press, and an offset printing apparatus having the blanket cylinder.

[0002]

2. Description of the Related Art A conventional method and apparatus for fixing a blanket to a blanket cylinder of a printing press has a metal fitting Fa on the end of the blanket as shown in Japanese Patent Application Laid-Open No. 7-1715 shown in FIG. , Fb are fixed, and a pressing member with which both end edges of the blanket engage is disposed in a groove provided parallel to the axis of the blanket cylinder so as to engage with a rack formed on the pressing member. There is a type in which a push-in member that rotatably supports a pinion is mounted by automatically pulling both end edges with the same tension by the displacement of the groove in the depth direction. As a method of fixing the end of the blanket similar to the conventional example, there is also known a structure in which a blanket metal fitting as shown in FIG. 9 is sandwiched by a large number of screws.

[0003]

However, the above-mentioned conventional blanket fixing method has the following problems. By providing a predetermined hole for positioning at the time of winding on the blanket and inserting this hole into a pin provided on the device, in the conventional setting method for winding the blanket, when the blanket has a large area, It is difficult to accurately process the cutting dimensions and the perforation dimensions of a blanket having a soft structure such as a cloth fabric. As a result, the ends of the blanket do not become parallel during setting, and a difference in length occurs in the left and right of the blanket in the width direction, which causes an unbalance in the left and right in the width direction when applying tension and winding. Was causing the

For example, when a blanket having a thickness of about 2.1 mm is wound and set on a blanket cylinder having a diameter of Φ550 with a tension set value of 1800 kgf, the parallelism between the ends of the blanket length of 1000 mm is about 1. When tension was applied to the blanket with an inclination of 5 mm, a difference of about 230 kgf was generated between the left and right tension values of the blanket width of 1000 mm. This difference in tension causes a decrease in the frictional resistance between the front surface of the blanket cylinder and the back surface of the blanket in areas where the tension is less than the specified value, and the blanket moves slightly due to the resistance during printing, resulting in inaccurate printing position in that area. Getting worse. In the area where the tension is higher than the specified value, the thickness of the wound state at the completion of winding setting will have the effect of thinning the blanket by stretching it, and for processes that try to give a certain printing pressure in the printing process. Adversely affects the crushing margin of the blanket.

For this reason, it is desirable to wind the blanket around the blanket cylinder without tension imbalance when setting the blanket. At the same time, for the fixed holding of the blanket, the desired tension value is about 2000.
Since it is as large as kgf, it is necessary that the structure does not cause slipping or loosening. In the fixing method as shown in FIG. 9 shown in the conventional example, in the case where the structure of the blanket has a base cloth layer as shown in JP-A-6-169189 of FIG. 10, for example, tension is applied to the blanket. It is confirmed that the blanket thickness gradually decreases as the tensile force is applied to. For that purpose, the blanket mounting state can be fixed and held in a parallel state between the end portions of the blanket without being influenced by the processing accuracy of the blanket in order to prevent printing misalignment, doublet, and other printing problems that occur during the printing process. There is a need for a method that allows tension to be applied while winding settings. An object of the invention according to the present application is to propose a method of fixing a blanket end for mounting a blanket on a blanket cylinder with a predetermined tension over the entire circumference, and a device therefor.

[0006]

In order to achieve the above object, the inventor of the present invention has been provided in a blanket cylinder in an offset printing apparatus in which a contact sliding movement in a printing process is performed by moving a table with respect to a rotating blanket cylinder. And a parallelizing device that has a fixed holding part and a part that applies a constant tension, and that enables metal fittings attached to both ends of the blanket between them to be positioned parallel to each other outside the device. The inventors have found that the above problems can be solved by forming the bracket shape into a wedge shape so that the blanket is clamped in a substantially N shape, and the present invention has been accomplished.

That is, according to the present invention, in a method of mounting a blanket on a blanket cylinder of an offset printing apparatus having a rotating blanket cylinder , a blanket metal fitting positioning step of positioning and mounting a fixing metal fitting in parallel to an end of the blanket is performed. A step of sandwiching the blanket with a concave portion on the fixed side having the same wedge wedge angle as the wedge shape in cross section of the positioned blanket metal fitting and fixing the metal fitting with a fixing part having another wedge shape.

Here, in the blanket metal fitting positioning step, the blanket is laid flat by a parallelizing jig which is attached to the offset printing apparatus and has a positioning for setting the metal fittings for fixing the ends in parallel with each other. it is not preferable to perform the structure capable of attaching a bracket and positioned parallel to the ends.

The present invention also provides a rotating blanket cylinder.
In the offset printing apparatus having, the mounting of the blanket on the blanket cylinder is performed by positioning the fixing metal fittings in parallel at the ends of the blanket and positioning the blanket metal fittings, and the cross-sectional wedge shape of the positioned blanket metal fittings. The blanket is sandwiched between the fixed concave portions having the same wedge inclination angle, and the metal fitting is fixed by a fixing component having another wedge shape. Here, the blanket fitting, it is not better good <br/> an apex angle which is less wedge cross-sectional shape 90 °.

[0010]

By adopting the above-mentioned structure, the parallelizing jig has the blanket placed in a flat state, and the pins which can be arranged with respect to the metal fittings attached to the both ends in a state where the four corners are pulled. When the side metal fittings are inserted and the upper metal fittings facing each other are sandwiched between the lower metal fittings and the blanket, the upper metal fittings at both ends are parallel to each other. It is characterized by a positioning pin or positioning contact member that can be positioned so that the blanket is placed on a flat plate-shaped blanket holder and the upper and lower blanket end fittings that are positioned and fixedly hold the blanket. Even if the precision of the machined mounting holes is poor, the brackets for fixing to the blanket are mounted parallel to each other at the end of the blanket. The action.

Further, the blanket end metal fitting is divided into upper and lower parts, and the blanket is sandwiched and fixed by the two metal fittings. The upper and lower holes can be positioned with respect to the parallelizing device, respectively. And has an outer shape. In addition, the shape of the metal fitting is an inverted trapezoidal wedge shape, and since the wedge mechanism is also used in the member for fixing the metal fitting to the blanket side and the table side, a large fixing force can be obtained with a small tightening force. It has the effect of being held, and acts to hold and hold the blanket so that slipping and loosening do not occur even if the blanket is pulled by a large tension.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a drawing showing a metal fitting for fixing the end of a blanket that best represents the features of the present invention and a parallelizing jig 2 for mounting the metal fitting in parallel with the blanket. Figure 1
In the middle, 1 is a blanket, and the blanket metal fittings 3 and 4 are attached to both ends la and lb of the blanket, and the blanket metal 5 is wound and fixed on the blanket cylinder 5.

The blanket end fittings 3 and 4 are divided into upper parts (3a and 4a) and lower parts (3b and 4b), and both ends 1a and 1b of the blanket 1 are sandwiched and fixed by these two sets of fittings. Then, the upper (3a and 4a) and the lower (3b and 4b) of the two metal fittings are the parallelizing jigs 2 respectively.
It has a hole that can be positioned with respect to, and an outer shape.

In the present embodiment, the lower (3b and 4b) metal fittings are groove-shaped arrangement holes 6a whose outer dimensions are digged according to the height of the lower metal fittings provided on the flat plate 2a of the paralleling jig 2. , 6
By inserting and fitting in b, it is possible to maintain and reposition the parallel positional accuracy. Top (3a
And 4a) two positioning holes 7a at both outer ends of the metal fitting,
7b, the pin 8a, 8b provided on the outside of the groove-shaped arrangement holes 6a, 6b on the flat plate 2a of the parallelizing jig 2 are parallel to each other in terms of positional accuracy and lower (3b and 4b) upper and lower fittings. It is constructed so that the combined position accuracy can be maintained and reproduced. Further, the shape in which the upper and lower metal fittings are combined is an inverted trapezoidal wedge shape and is used when fixing the blanket end metal fittings 3 and 4 to the fixed base 10 on the blanket cylinder 5 side and the fixed base 11 on the table 9 side. The structure is such that a large fixing force is obtained by the effect of wedges.

The fixed base 11 has a first pawl and a second hook for pulling the table 9 to apply a tension to the blanket 1 in order to transfer the fixed base 11 to the blanket cylinder 5 at the end of the blanket winding. The claws are configured on the front and back. The parallelizing jig 2 has a flat plate 2 having an area in which the blanket 1 and the metal fittings 3 and 4 can be arranged.
a, and on the flat plate 2a, the lower part (3b and 4)
b) In addition to the groove-shaped arrangement holes 6a and 6b for positioning the metal fittings and the pins 8a and 8b for positioning the upper (3a and 4a) metal fittings, the blanket 1 is roughly positioned with respect to the two metal fittings 3 and 4. For the purpose of determining the blanket, the blanket itself is placed in a flatly stretched state without wrinkles, slack, etc., and four pins 12 are provided at positions corresponding to substantially four corners of the outer shape of the blanket 1. The blanket 1 has a hole 13 to be inserted into the pin 12.

FIGS. 2 and 3 are views showing a portion for fixing the blanket metal fittings 3 and 4 on the offset printing apparatus. In the drawings, 10 (and 11) is a fixed base having an opening, and the slopes 14 to 14 are sloped. Sixteen wedge-shaped mating surfaces are formed. The opening of the fixed base 10 (and 11) has an edge portion 17 serving as a fixed end outlet.

The blanket 1 is folded at the edge portion 17 to maximize the friction with the back surface of the blanket, so that the tension does not directly act on the wedge portion. The slopes 18 and 19 forming the inverted trapezoid of the cross-sectional shape of the blanket metal fitting 3 (and 4) have the same slope angle as the wedge slopes 14 and 15 and have a wedge structure that fits with the blanket 1 sandwiched therebetween. . Fixed base 10 (and 1
Positioning in 1) is performed by fitting a positioning pin and a hole. In this embodiment, two or more positioning pins 21 that engage with the positioning holes 20 provided in the fixed base 10 (and 11) are provided at the apex angle portion of the blanket metal fittings 3 (and 4). The blanket metal fitting 3 in which the worker has set the blanket 1 into the positioning hole 20.
By inserting the positioning bins 21 (and 4), the positional relationship between the blanket 1 and the blanket cylinder 5 is determined.

The blanket metal fittings 3 (and 4) are interlocked with the operation of the fixed wedge parts 22 (for example, a link mechanism) so that the blanket metal fittings 3 (and 4) are attached to the wedge alignment slopes 14 and 15 of the fixed base 10 (and 11). ) The wedge alignment slopes 18 and 19 of FIG. At this time, the blanket 1 is bent by the wedge slope and sandwiched. As for the pinching force F at that time, the force P given by the tightening screw 23 for fixing the fixed wedge part 22 to the fixed base 10 (and 11) is the blanket metal fitting 3
(And 4) is obtained by the action increased by the angle of the wedge mating slopes 18, 19.

FIG. 4 shows an offset printing apparatus. A blanket is attached and the blanket of the embodiment is fixed using this printing device. In FIG. 4, 101 is a main body base to which two linear guides 102 on the left and right are attached. Moving block 103 on the linear guide 102
A table 104 is fixed to the ball screw 1 which is rotatably driven by a table drive motor 105 in front of the device.
By 06, it is possible to travel while controlling the amount of movement in the front and rear (X direction). The amount of movement of the table 104 at this time is detected by a length measuring device (not shown).

The blanket cylinder 5 arranged so as to have an axis line at a right angle (Y direction) to the traveling direction of the table is rotatably supported by support columns 108 at both ends. The blanket cylinder 5 can be rotated by controlling a rotational movement angle by a blanket cylinder drive motor 110 combined with a speed reducer 109 arranged on an axis extension line. The rotational movement amount of the blanket cylinder 5 at this time is detected by an encoder or the like (not shown). Reference numeral 111 denotes a gear fixed to both the left and right sides of the blanket cylinder 8, which meshes with a rack gear 112 fixedly attached to the left and right of the upper surface of the table 104 to realize a synchronizing operation in the printing process. The stroke of the printing process is sufficiently short with respect to the total stroke of the table 104, and the length of the rack gear 112 is determined in consideration of the length of the work 120 in the X direction + the tuning stable stroke. As a result, the blanket cylinder 5 and the table 104 are brought into contact with the gear 111 and the rack gear 112 only during the printing process stroke, and the blanket cylinder 5 and the table 104 can individually perform numerical control operation in other stroke regions.

As shown in FIGS. 2 and 3, blanket metal fittings 3 (and 4) are attached to both ends of the blanket 1 mounted on the blanket cylinder 5. The blanket cylinder 5 is provided with a fixed holding portion 115 in which a fixed base 10 for fixing and holding the blanket metal fitting 3 is fixed and held in parallel with the axis of the cylinder.
In order to realize the transfer of the fixed base 11 including the other blanket metal fitting 4, there is a movable holding portion 116 which can be displaced in the tangential direction of the blanket cylinder diameter.

A tension jig 117 is mounted on the table 104.
Is provided so that the fixed base 11 including the blanket metal fitting 4 attached to one end of the blanket 1 can be attached and detached. The tension jig 117 has a load cell 118 capable of detecting the force for holding the fixed base 11, and the tension generated in the blanket 1 can be sequentially output.

The table drive motor 105 and the blanket cylinder drive motor 110, individually by a control device not shown the figure, or can numerically controlled tuning operation. Further, to the control equipment, the output of the load cell 118, and Table 1
Movement amount of 04, and is connected to capture rotational movement of the blanket cylinder 5.

5 and 6 are conceptual views showing a method of mounting and fixing the blanket 1 on the blanket cylinder 5 in the offset printing apparatus of FIG. 4 in the order of steps, and the reference numerals are the same as those in FIG. A method for mounting and fixing the blanket 1 of the present invention will be described with reference to FIGS.

First, a groove-shaped arrangement hole 6a for positioning the lower metal fitting, which is provided on the flat plate 2a of the parallelizing jig 2 attached to the apparatus,
The lower brackets 3b and 4b of the blanket brackets 3 and 4 are fitted to the 6b and positioned. At this time , the groove depth is the same as the height of the lower metal fitting, so after inserting the lower metal fitting , the groove will be filled ,
The flat plate 2a becomes flat. Next, put the blanket 1 on the flat plate 2a.
The four pins 12 on the flat plate 2a provided for the purpose of arranging the blanket brackets 3 and 4 on the blanket metal fittings 3 and 4 to determine the arrangement.
Fit the holes 13 at the four outer corners of the blanket 1,
Place the blanket 1 without wrinkles or sagging.

Next, pins 8a and 8b provided outside the groove-shaped arrangement holes 6a and 6b on the flat plate 2a of the parallelizing jig 2.
The holes 7a, 7b provided in the upper metal fitting are inserted into the upper metal fitting 3a, the upper metal fitting 3a
4a is positioned with respect to the lower metal fittings 3b, 4b, and the upper and lower parts are connected and fixed with screws or the like. Up to this state is the process of preparing outside the device, the blanket metal fittings prepared here are
When the blanket 1 accurately attached in parallel to both ends is brought into the apparatus, the metal fitting 3 on one side is engaged with the positioning pin 21 and the positioning hole 20 on the fixed base 11 on the table 104 side, and the fixed wedge part 22 is operated. , The blanket metal fitting 3 is moved in conjunction with this (for example, by a link mechanism not shown), and the wedge slopes 18 and 19 on the blanket metal side and the wedge slope 14 on the fixed base side,
The blanket 1 is sandwiched by 15.

At this time, the blanket 1 is bent into an acute angle at a wedge angle θ ₁ formed by the wedge mating surfaces 18, 19 (14, 15), and the wedge mating slope 23 of the fixed wedge part 22 is fixed to the fixed base 11. Wedge slope 1
It becomes a temporary fixed state when it is combined with 6. Next, the fastening screw 24 is inserted into the fastening portion provided on the fixed wedge component 22 to fix the fixed wedge component 22 to the fixed base 11. This tightening force P is decomposed into a force for pressing the blanket fitting 3 by the wedge-matching slopes 16 and 23, and the blanket 1 is fixed with a stronger force F. This is set by engaging the second claw 26 of the fixed base 11 with the tension jig 117 attached to the front of the printing method of the table 104 on the apparatus. (FIG. 5a) The other metal fitting 4 of the blanket 1 is passed under the blanket cylinder 5 to fix the fixed holding portion 1 on the blanket cylinder 5.
When the positioning pin 21 and the positioning hole 20 are engaged with the fixed base 10 of 15, and the fixed wedge part 22 is operated,
The blanket fitting 3 is moved in conjunction with this (for example, by a link mechanism (not shown) or the like), and the blanket 1 is sandwiched by the wedge slopes 18 and 19 on the blanket fitting side and the wedge slopes 14 and 15 on the fixed base side.

At this time, the blanket 1 is bent into an acute angle at a wedge angle θ1 formed by the wedge mating surfaces 18, 19 (14, 15), and the wedge mating slope 23 of the fixed wedge part 22 is wedged by the fixed base 11. Mating slope 1
It becomes a temporary fixed state when it is combined with 6. Next, the fastening screw 24 is inserted into the fastening portion provided on the fixed wedge component 22 to fix the fixed wedge component 22 to the fixed base 11. This tightening force P is decomposed into the force for pressing the blanket metal fitting 3 by the wedge mating slopes 16 and 23,
The blanket 1 is fixed with a stronger force F.

At this time, the stroke position of the table 104 moves to L1 which is shorter than the natural length L of the blanket 1 and is stopped, so that the blanket 1 is attached to the apparatus with a slack. (FIG. 5b) After fixing the blanket 1 to the fixed holding portion 115 of the blanket cylinder 5, the blanket cylinder 5 is tangentially extended from the blanket cylinder 5 and is stopped by rotating the blanket cylinder 5 until the blanket 1 is horizontal. The table 104 for the same stroke as the amount also operates at the same time, and the L1 length does not change.

Next, with the blanket cylinder 5 stopped, the slack of the blanket 1 is removed from the table 104 (+).
It moves in small amounts in the X direction) and stops when the output f0 of the load cell 118 is detected. Output f0 at this time
Indicates that the blanket 1 is stretched without slack, and the natural length L of the blanket 1 can be obtained by measuring the moving stroke of the table 104 with a length measuring device. (FIG. 5c) From this position, the set tension value F is applied to the load cell 118.
With the blanket cylinder 5 stopped until the output of
The table 104 is moved in the + X direction by a small amount. When the set tension value F equals the load cell output value f, the load is stopped, and the tension f is applied to measure the amount of expansion of the blanket 7 as the movement amount ΔL of the table 104 by the length measuring device. (FIG. 6 d) From here, the rotation angle of the blanket cylinder 5 and the table 104
The amount of movement is synchronized with the position control so that the tension f is maintained and winding is performed. At this time, the output value of the load cell 118 is
It is taken into the control as a correction of the position control. The winding operation is continuously stopped until the edge movement holding portion 116 of the blanket cylinder 5 comes to the bottom and the edge holding portion becomes horizontal. (FIG. 6e) In this state, the blanket edge 114 is engaged with the edge movement holding portion 116, and the output value of the load cell 118 is -Δ.
The edge moving / holding portion 116 is advanced until f. That is, the tension f is not released midway, and the edge movement holding portion 11 of the blanket cylinder 5 is removed from the tension jig 117.
The holding state is transferred to 6. After that, the edge movement holding portion 116 and the blanket edge portion 114 are fixed with bolts or the like, and the tension jig 117 is removed from the table 104. (FIG. 6f) The blanket mounting and fixing is completed through the above steps. Figure 7
Represents the relationship between the force P given by the tightening screw 24 and the pinching force F that fixes the blanket 1 by the angle θ of each wedge slope. That is, this example shows that a large blanket fixing force can be obtained with a smaller number of tightening screws as compared with the conventional fixing method. According to this, the blanket fixing force conventionally obtained by using 19 screws with a diameter of 6 mm is about 9600 kgf, whereas the same tightening effect according to the present embodiment is obtained by using 6 screws with a diameter of 6 mm. (Blanket presser wedge slope angle 5 °, fixed wedge slope angle 10 °)

The features of this embodiment will be described below. In the above-mentioned method for fixing the end metal fittings of the blanket in parallel accuracy and mounting method to the blanket cylinder, firstly, without being affected by the deterioration of the accuracy of cutting and drilling as the blanket becomes large (large area). A major feature is that it is easy to maintain the parallel accuracy of fixing the blanket, which was the cause of unbalanced tension. Secondly, it is a great feature that a large fixing force is obtained by combining the wedge-shaped pressing parts and by a small tightening force (that is, the number of screw tightening work steps is reduced). Further, by forming the edge portion 17 serving as a fixed end outlet in the opening portion of the fixed base 10 (and 11), the blanket 1 is folded to maximize the friction with the back surface of the blanket and the tension is not directly applied to the wedge portion. The feature is that it works.

[0032]

As described above, in the conventional blanket winding method, the blanket itself, which has been a problem when the blanket becomes large in size (large area) , is cut into the soft structure of the cloth fabric. Since it is difficult to machine the dimensions and the dimensions of the holes with high precision , the tension imbalance caused by the positioning error is a problem.
Was becoming. In contrast, according to the present invention, a metal fitting for fixing the blanket end which is vertically divided, by parallel-out jig which can assembled to blanket the fitting outside of the apparatus, the blanket cylinder the blanket ends winding setting that gave the tension that has been set unbalance not to attach parallel to it has become possible.

Further, by utilizing the wedge effect due to the shape of the metal fitting for fixing and holding the blanket, even if the blanket is pulled by a large tension at the time of winding, it will not slip or loosen. Further, since the wedge mechanism is used also in the fixing means, there is an effect that a large fixing force can be obtained with a small tightening force.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a blanket fitting and a parallelizing jig according to an embodiment of the present invention.

FIG. 2 is a diagram showing a fixed portion of a blanket metal fitting according to an embodiment of the present invention.

FIG. 3 is a diagram showing a fixed portion of a blanket metal fitting according to an embodiment of the present invention.

FIG. 4 is a perspective view showing an offset printing apparatus according to an embodiment of the present invention.

FIG. 5 is a diagram showing a procedure for mounting a blanket on a blanket cylinder in the apparatus shown in FIGS.

FIG. 6 is a diagram showing a procedure for mounting a blanket on a blanket cylinder in the apparatus shown in FIGS. 2 and 3.

FIG. 7 shows the relationship between the tightening force and the blanket fixing force according to the embodiment of the present invention.

FIG. 8 is a perspective view of a conventional blanket mounting device.

FIG. 9 is a method of fixing a blanket end of a conventional example.

FIG. 10 is a sectional view of a conventional blanket.

[Explanation of symbols]

1: blanket, 2: parallelizing jig, 3-4: blanket fitting, 3a, 4a: upper fitting of blanket fitting,
3b, 4b: lower bracket of blanket metal fitting, 5: blanket cylinder, 6a, 6b: groove-shaped arrangement hole for positioning lower metal fitting,
7a, 7b: Upper metal fitting positioning hole, 8a, 8b: Upper metal fitting positioning pin, 9: Table, 10, 11: Fixed base,
12: Blanket arranging pin, 13: Blanket arranging hole, 14-15: Wedge mating slope (fixed base side), 16: Wedge slope (fixed base side), 17: Edge, 18-19: Wedge mating slope ( Metal fitting side), 20: Hole for blanket metal fitting positioning, 21: Pin for blanket metal fitting positioning, 22: Fixed wedge part, 23: Wedge mating slope (fixed wedge part side), 24: Tightening screw, 25: First Claw (fixed base on the table side), 2
6: Second claw (fixed base on the table side), 101: Main body base, 102: Linear guide, 104: Table,
105: table drive motor, 106: ball screw,
110: blanket cylinder drive motor, 114: edge,
115: fixed holding part, 116: moving holding part, 11
7: tension jig, 118: load cell.

Claims (4)

(57) [Claims] 1. A method of attaching a blanket to a blanket cylinder of an offset printing apparatus having a rotating blanket cylinder , wherein a fixing metal fitting is positioned parallel to an end of the blanket and is attached. And a step of sandwiching the blanket with a fixed-side recess having the same wedge angle as the wedge shape of the cross section of the positioned blanket metal fitting and fixing the metal fitting with a fixing part having a different wedge shape. Characteristic blanket mounting method. 2. The blanket metal fitting positioning step comprises:
It is possible to attach the metal fittings that are positioned parallel to both ends to the blanket laid flat by a parallelizing jig that is attached to the offset printing device and has the positioning to set the metal fittings for fixing the ends in parallel with each other. The blanket mounting method according to claim 1, wherein the blanket mounting method is performed by a different structure. 3. An offset printing apparatus having a rotating blanket cylinder , wherein mounting of the blanket on the blanket cylinder is performed by positioning a fixing metal fitting in parallel at an end of the blanket. And a mechanism that clamps the bracket with a fixed part having another wedge shape by sandwiching the blanket with a recess on the fixed side having the same wedge angle as the wedge shape of the cross-section of the positioned blanket metal fitting. The offset printing apparatus is characterized in that Wherein said blanket fitting, according to claim 3, characterized in that the apex angle is less wedge cross-sectional shape 90 °
The offset printing apparatus described in.