JPH0533343Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a doctor blade used in an ink supply device of a printing press.

(Prior Art) FIG. 5 shows an ink supply device of a conventional offset rotary press, in which ink A in an ink tank 1a is collected by a screw (not shown), sucked by a pump 2, and filtered by a filter 3 to collect paper powder in the ink. After removing ink and foreign matter, the ink is supplied from the ink discharge nozzle 4 to the ink source roller 5a.

The ink supplied to the ink source roller 5a is made into a constant film thickness by the ink supply blade 6 and the gap 6c between the blade 6 and the ink source roller 5a, and is transferred to the high-speed delivery roller 7 at different circumferential speeds.
After being supplied to the plate cylinder 10 via the doctor roller 8 and the ink forming rollers 9a and 9b, it is further transferred to the printing press 12 via the blanket 11.

1b is a dampening water tank, and the dampening water B adheres to the water source roller 5b, is scattered by the rotation of the brush roll 13, and adheres to the water reciprocating rotor 14, and is located in front of the ink forming rollers 9a and 9b. Swimsuit roller 15
The ink is transferred to the plate cylinder 10 to form a water film on the surface of the non-image area of the plate, thereby preventing the ink from transferring to the non-image area.

Moreover, the excess water in the dampening water in the plate cylinder 10 is
The water-containing ink remaining on the doctor roller 8 is transferred from the plate cylinder 10 to the doctor roller 8 through the ink form rollers 9a, 9b together with the surplus ink after being supplied to the plates on the ink form rollers 9a, 9b.
The ink is scraped off by the hysteresis doctor blade 17 and collected in the ink tank 1a, sucked out again by the pump 2, reused, and circulated.

The doctor roller 8 is a copper-plated roll, and the history doctor blade 17 is held in a blade holder 16, protrudes 10 mm from the holder 16 as shown in FIG. 6, and contacts the doctor roller 8 at an angle of 30°. The history doctor blade 17 has a width of 800 mm and a length of 50 mm, as shown in Fig. 4.
It is a plate-like piece with a thickness of 0.15 mm.

As described above, in printing machines, a doctor blade is often used to remove excess ink and stains from paper dust on the rollers. This doctor blade wears out due to sliding with the mating roller, foreign matter in the ink, paper dust, etc., so a hardened copper blade was used.

However, since the blade life due to wear is extremely short, a blade material with excellent wear resistance has been desired in order to extend the life. Therefore, attention was focused on hard chrome plating because it has high hardness, no processing distortion, and good contact with metal, and it was discovered that blades coated with hard chrome plating have a long life.

(Problems to be solved by the invention) In the conventional ink supply device of an offset rotary press shown in Fig. 5, the doctor roller is a copper-plated roll,
The history doctor blade is made of SK steel (SK-5, hardness
Hv540), but the blade life with 5mm wear is
Even with Ni-P electroless plating (Hv2000), which has a shorter hardness of 10 to 15 days, it does not improve much. The lifespan of hard chrome-plated blades is 40 to 60 days, which is longer than that of SK steel, but it also saves you the trouble of replacing blades.
In order to improve the working efficiency of printing presses, blades with even longer lifespans are desired.

(Means for solving the problem) The present invention was proposed to solve the above problem, and is an ink supply characterized by coating the outer peripheral surface of a thin metal plate with a hard carbon film. This relates to the doctor blade of the device.

(Function) The hard carbon film coated on the outer peripheral surface of the thin metal plate that forms the main body of the doctor blade according to the present invention not only has high hardness and excellent wear resistance, but also has self-lubricating properties. Because
Adhesive wear can be prevented and the metal roll surface will not be damaged.

Furthermore, by using a composite coating of the hard carbon film and hard chrome plating, the wear resistance is further improved.

(Example) The present invention will be described below with reference to the illustrated embodiments.

FIG. 1 shows an example in which the present invention is applied to the ink supply device shown in FIG.
The blade 17 is made of SK steel (SK-5 hardness Hv540) with a width of 800 mm, a length of 50 mm, and a thickness of 140 μm.
This is a 5-μm-thick hard carbon film 18 coated on both sides of the blade over an area extending beyond the protruding length from the blade holder (40 mm).

Next, four types of SK steel, hard chrome plating, hard carbon film coating, and composite coating of hard chrome plating and hard carbon film were subjected to wear tests using the testing apparatus shown in FIG. 2. In FIG. 2, 18 is a test blade, and its dimensions are 35 mm in width, 50 mm in length, and 150 μm in thickness. 19 is a test roll, which has a diameter of 180 mm, a width of 50 mm, and a copper-plated surface. 20 is an ink leveling blade, and 21 is an ink leveling roll. The ink 22 in the ink tank 23 is supplied to the upper part of the test roll 19 by a pump 24, leveled by an ink leveling blade 20 and an ink leveling roll 21, and then scraped off by the test blade 19. In addition, 25 in the figure shows the test blade 18 as the test roll 1.
It is a spring that presses to 9. The test blade 18 was pressed against the test roll 19 with a contact angle of 30° and a pressing force of 135 g/cm by the spring 25, and the test roll 19 rotated at a peripheral speed of 500 m/min in the direction of the arrow. The ink 22 used is K-3 manufactured by Sakata Shokai.
It contains almost no water.

FIG. 3 shows the results of the test using the test device.
In FIG. 3, the abrasion volume is represented by the abrasion volume, which was calculated by measuring the abrasion weight loss and subtracting it by the average specific gravity of the base material and coating. From FIG. 3, it was found that the wear of the carbon film and composite coating was much lower than that of the others.

(Effects of the invention) As described above, since the doctor blade according to the invention is constructed by coating the outer peripheral surface of a thin metal plate with a hard carbon film, the amount of wear is significantly less than that of the conventional doctor blade. Longer lifespan. Furthermore, this reduces the frequency of replacing the doctor blade, improving the operating efficiency of the printing press and improving economic efficiency.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing an embodiment of the doctor blade according to the present invention, Fig. 2 is a side view showing the schematic configuration of a doctor blade wear test device, Fig. 3 is a chart showing the wear test results, and Fig. 4 is a diagram showing the wear test results. 5 is a perspective view of a conventional doctor blade, FIG. 5 is a longitudinal sectional side view of a conventional general offset rotary press, and FIG. 6 is a detailed view of the main parts in FIG. 5. 17...History doctor blade, 18...Carbon film.

Claims (1)

[Claims for Utility Model Registration] (1) A doctor blade for an ink supply device characterized by coating the outer peripheral surface of a thin metal plate with a hard carbon film. (2) A doctor blade for an ink supply device as claimed in the utility model registration claim, in which the outer peripheral surface of a thin metal plate is plated with hard chrome and a hard carbon film is coated thereon.