JP2540519B2 - Ink supply device doctor blade - Google Patents

Description

TECHNICAL FIELD The present invention relates to a doctor blade used in an ink supply device of a printing machine.

(Prior Art) An example of a conventional ink supply device for an offset rotary press will be described with reference to FIG. 5. Ink A in the ink tank 1a
Are collected by a screw (not shown) and sucked by the pump 2, paper dust and foreign matters in the ink are removed by the filter 3, and 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 to have a constant film thickness by the ink supply blade 6 and the gap 6c, transferred to the high-speed delivery roller 7 at different peripheral speeds, and the doctor roller 8 and the ink application rollers 9a and 9b are transferred. After that, it is supplied to the plate cylinder 10. Further, it is transferred to the printing paper 12 via the blanket 11.

1b is a dampening water tank, and dampening water B adheres to the water source roller 5b, is scattered by the rotation of the brush roller 13 and adheres to the water reciprocating roller 14 and is located in front of the inking rollers 9a and 9b. After passing through the roller 15, it is transferred to the plate cylinder 10 to form a water film on the surface of the non-image area of the plate to prevent the ink from transferring to the non-image area.

Excess water in the dampening water on the plate cylinder 10 is transferred from the plate cylinder 10 through the inking rollers 9a, 9b to the inking rollers 9a, 9b.
Doctor roller 8 together with the excess ink after being supplied to the plate on 9b.
The residual water-containing ink transferred to the doctor roller 8 is scraped off by the history doctor blade 17 and collected in the ink pan 1a, sucked again by the pump 2 and reused for circulation.

By the way, the doctor roller 8 is a copper plating roll, the history doctor blade 17 is spring steel (SK-5, hardness HV540),
The blade 17 is held by the blade holder 16,
As shown in FIG. 6, it projects 10 mm from the holder 16 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 m, as shown in FIG.
m, thickness 0.15 mm.

As described above, in a printing machine, a doctor blade is often used in order to remove excess stains on the rollers due to ink and paper dust. Since this doctor blade is abraded by sliding with the mating roller, foreign matter in the ink, paper dust, etc., it has been used hardened steel with high hardness.

(Problems to be Solved by the Invention) In the ink supply device for the conventional offset rotary press shown in FIG. 5, the doctor roller is a copper plating roll and the history doctor blade is SK steel (SK-5, hardness HV540). But 5
mm wear of the blade life is as short as 10 to 15 days, even those further subjected to N _i -P electroless plating (Hv 1000) with higher hardness, not so much improved.

The doctor blade that is commonly used is spring steel (SK-
Hardened 5), the hardness is about HV540, but depending on the use environment, these will wear 1-5 mm in 10-30 days,
I had to replace it. As described above, the conventional doctor blade has a short service life and needs to be replaced frequently, which not only deteriorates the working efficiency of the printing press but is also economically disadvantageous.

The present invention is intended to provide a doctor blade with a small amount of wear and a long life. (Means for Solving the Problems) For this reason, according to the present invention, the ink supplied onto the doctor roll whose surface is copper-plated is scraped uniformly and thinly on the outer peripheral surface of the blade made of a thin plate made of spring steel. It is provided with a chrome-plated layer and is used as a means for solving problems.

(Operation) In order to reduce wear, the present invention is one in which hard chrome plating is applied to both sides of the blade so that the hardness is large, there is no processing strain, and the contact relationship with the copper-plated doctor roll is good. is there. Also, since chromium easily oxidizes, an oxide film is easily formed on the surface even when it comes into contact with a copper-plated doctor roll, and adhesion wear is prevented, so it is effective in increasing hardness and extending the life. .

(Embodiment) The present invention will be described below with reference to embodiments of the drawings.
The figure is a perspective view of a history doctor blade 17 in which the present invention is applied to the ink supply device shown in FIG. 5, and the blade 17 has a width of 800 mm, a length of 50 mm, and a thickness of 100 μ of SK steel (SK-
5 hardness of HV540), on both sides over the range (40 mm) beyond the protruding length from the blade holder,
It is formed by applying a hard chrome plating 18 having a thickness of 25μ.

The following tests were performed in selecting this blade. That is, first, to obtain wear resistance, the hardness HV
List the coating methods that are over 1000,
The strain when they were processed was measured. Length 1m,
We put stainless steel (SUS304) with a width of 50 mm and a thickness of 0.1 mm with various coatings on the surface plate and measured the gap formed between the surface plate and the surface plate. As a result, were as shown in Table 1, it was found N _i -P electroless plating, chrome plating, those not coated is good.

Next, four kinds of spring steel (SK-5) added to the above-mentioned three kinds were subjected to a wear test with a test apparatus shown in FIG. In Fig. 2, 18 is a test blade, and the width is
The thickness was 35 mm, the length was 50 mm, and the thickness was 150 μ. 19 is a test roll with a diameter of 180 mm and a width of 50 mm, the surface of which is steel-plated. 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 the pump 24, leveled by the ink leveling blade 20 and the ink leveling roll 21, and scraped off by the test blade. Reference numeral 25 is a spring that presses the test blade 18 against the test roll 19. The test blade 18 has a contact angle of 30 ° with the test roll 19 and a pressing force of 135 g by the spring 25.
Pressed at / cm. The test roll 19 rotates at a peripheral speed of 500 m / min in the direction of the arrow. Ink 22 is made by Sakata Shokai K-
At 3, it contained almost no water.

As a result, the test results are shown in FIG. In FIG. 3, the wear amount is represented by the wear volume, and the wear weight loss was measured and calculated by dividing it by the average specific gravity of the base material and the coating. As can be seen from FIG. 3, the wear of the chrome plating was found to be significantly lower than the others.

When the blade shown in FIG. 1 was mounted on the actual machine shown in FIG. 5 and subjected to an endurance test, it was 40 to 60 days until 5 mm wear under the same conditions as spring steel (SK-5). .

(Effects of the Invention) As described above, the present invention is a chrome-plated layer on the outer peripheral surface of a blade made of a spring steel thin plate for uniformly and thinly scraping off ink supplied on a doctor roll having a copper-plated surface. As a result, the blade has a small distortion, and a blade with significantly improved wear resistance can be obtained by combining with a doctor roll plated with copper. In addition, this reduces the frequency of replacement of the doctor blade, prevents deterioration of the working efficiency of the printing machine, and improves the economy.

[Brief description of drawings]

FIG. 1 is a perspective view of a doctor blade showing an embodiment of the present invention, FIG. 2 is a side view showing a schematic structure of a wear test device, FIG. 3 is a view showing wear test results, and FIG. FIG. 5 is a perspective view of a doctor blade of FIG. 5, FIG. 5 is a side sectional view of a conventional general offset rotary press, and FIG. 6 is a detailed view of a main part in FIG. Explanation of the main parts of the figure A …… Ink 1a …… Ink tank 5a …… Ink source roller 7 …… Transfer roller 8 …… Doctor roller 16 …… Blade holder 17 …… History doctor blade 18 …… Chrome plating

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hidenori Yamane, Inventor 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima-shi, Hiroshima Mitsubishi Heavy Industries, Ltd. Hiroshima Research Institute (72) Inventor Katsuhiko Morimoto Kannon, Nishi-ku, Hiroshima-shi, Hiroshima 4-6-22 Shinmachi, Mitsubishi Heavy Industries, Ltd. Hiroshima Research Laboratory (56) Reference JP-A-58-42463 (JP, A) US Patent 2404689 (JP, A) International Publication 61093 (WO, A)

Claims (1)

(57) [Claims] 1. A chrome-plated layer is formed on the outer peripheral surface of a blade made of a spring steel thin plate that scrapes the ink supplied onto a doctor roll whose surface is copper-plated uniformly and thinly. Doctor blade for ink supply device.