JPH0639991A - Scratching off blade - Google Patents

Abstract

PURPOSE:To obtain peeling off resistance and corrosion resistance of a scratching off blade as well as its affluent toughness and wear resistance also by a method wherein an edge part of a blade is formed by a ceramic sintered body wherein an ion is implanted in its front face, rear face and side face. CONSTITUTION:An edge part of a blade 1 is composed of a ceramics sintered body, and an ion 7 is implanted into a front face 4, a rear face 5, and both side faces 6 other than a contact face with a plate surface 2 of the edge part. Then, the ceramics should preferably be stabilized zirconia or alumina ceramics sheet (50mum) containing Y2O3 and MgO from a standpoint of high hardness, high strength, sheet workability, etc. However, when heat expansion, heat conductivity, etc., are regarded as important, alumina may be used. Energy to be implanted should be preferably from several tens kev to 1000kev, and an implantation quantity should be preferably 10<5>-10<8> ion/cm<2>.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scraping blade applied to a printing plate of a printing machine.

[0002]

2. Description of the Related Art For example, a scraping blade used to scrape off excess ink adhering to the plate surface of a printing plate to prevent background stains during printing and to keep the ink film thickness constant is shown in FIG. As shown in FIG. 6, the edge is ground obliquely to sharpen the portion that comes into contact with the plate surface, and further, the shape of FIGS. 7 and 8 in which the entire blade or only the tip is extremely thin It is used.

Most of these scraping blades are made of a hard metal such as tool steel or high speed steel or a hard surface treatment material such as plating or thermal spraying. Further, in recent years, a scraping blade made of a sintered material of ceramics such as zirconia has been studied, but all of them have problems such as high wear rate and chipping of the blade.

[0004]

Since the scraping blade scrapes the printing ink on the plate surface while bringing the blade edge into contact with the plate surface of the printing plate, the blade edge wears sharply due to impurities in the ink, paper dust, etc. Wear resistance is not so high,
It also has a short life due to corrosion from plating. As shown in FIG. 5 and FIG. 6, when the tip is processed obliquely, the blade edge gradually wears during the printing process and the contact area with the plate surface changes (increases), which leads to a change in the color tone of the printed matter. Therefore, the cycle of re-grinding or replacement of the blade is short, and the time required to replace the blade, various operations required to reproduce the color tone, and a loss such as an increase in wasted paper occur.

On the other hand, the thin and uniform thickness as shown in FIGS. 7 and 8 can solve the above-mentioned problems, but the thin steel alone has a high wear rate, and hard Cr plating or Al ₂ O ₃
Surface coating materials such as thermal spraying, and hard ceramics alone have also been studied. However, even if the surface coating is applied to the contact surface with the plate surface, only a short time effect can be obtained, and it is a considerable film to increase the average hardness of the entire blade by applying it to the non-contact surface, that is, the front and back surfaces of the blade. Since a thick film is required, the adhesion of the coating film is reduced due to a thick film, and the scraping performance is deteriorated (the thickness of the ink remaining on the plate surface after scraping is large) due to the increase in the total thickness of the blade. On the other hand, hard ceramics are extremely excellent in terms of wear resistance, but they are inferior in toughness and are liable to cause blade spillage, which also lacks reliability in high-quality printing.

The present invention has been developed to address such problems, and an object of the present invention is to provide a hard ceramic blade having excellent toughness.

[0007]

The structure of the present invention for achieving the above object will be described with reference to FIG. 1 and FIG. 2 corresponding to the embodiments. In the present invention, the blade portion of the blade 1 is a front surface 4 and a back surface. 5 and side surfaces 6 are formed of a ceramics sintered material in which ions 7 are implanted.

[0008]

According to the present invention, the blade portion made of the hard ceramics sintered material is significantly improved in wear resistance as compared with steel by the above-mentioned means, so that it is possible to reduce the thickness and improve the scraping performance of the printing plate surface and the printed matter. Stabilization of color tone is obtained. In addition, compressive residual stress is added to the surface layer of ceramics by ion-implanting various elements on the front, back and side surfaces of the blade, and at the same time, the toughness of the surface layer is improved and damage such as cracks and chips is greatly A scraping blade with a long life can be obtained, and ion implantation does not increase the thickness like other coating films (plating, thermal spraying, ion plating, etc.) and does not cause a temperature rise. A stable scraping blade can be obtained without peeling and deterioration of the substrate.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. Reference numeral 1 denotes a scraping blade, and the blade portion of the blade 1 is made of a ceramic sintered material, and a plate surface 2 of the blade portion is used. Ions 7 were implanted into the front surface 4, the back surface 5 and both side surfaces 6 other than the contact surface 3 with. The ceramic used in the present invention are Y ₂ O ₃ having a high hardness, high strength properties and sheet processability and the like, M
A thin plate (50 μm) of stabilized zirconia containing gO and alumina ceramics is desirable, but alumina may be used when thermal expansion, thermal conductivity, etc. are important. The type of ions to be implanted is not particularly limited because this implantation focuses on improving the toughness.

If the implantation energy is less than several tens keV, the energy cannot sufficiently enter the substrate. [For example, refer to page 1 of "Volume 26, No. 4 (1983), pages 287 to 293," Modification and thin film formation by combined use of ion implantation and vapor deposition ". If it exceeds 1000 kev, the substrate surface and the formed film are reversely sputtered and it is difficult to form the film. Therefore, the range is preferably several tens kev to 1000 kev.
On the other hand, considering the injection distribution and the injection time, the injection amount is preferably 10 ⁵ to 10 ⁸ ions / cm ^{2 in the} above energy range. FIG. 2 shows the abrasion test with a test machine in which the actual printing cylinder is modified using Examples 1 to 5 of the scraping blade of the present invention as shown in Table 1 and Comparative Examples 1 to 4 using various conventional blades. This is the result.

[0011]

[Table 1]

It can be seen that the blade having chrome plated SK5 has a remarkably high wear rate, and a thin blade cannot be expected to have a long life. On the other hand, in the case of ceramics alone, although the initial wear rate was low, the amount of wear increased rapidly at a certain point and a streak pattern was recognized on the printing plate surface at the same time. At this point, when the tip of the blade was inspected, a local defect was generated starting from the surface side of the blade as shown in FIG.
It was confirmed that the sharp increase in the amount of wear and the streak pattern on the printing plate surface were due to this defect.

In Examples 1 to 5 of the present invention, the same zirconia and alumina ceramics as those of Comparative Examples 2 to 4 were implanted with Ti ⁺ , N ⁻ and Cr ⁺ under the conditions shown in Table 2 on the front and back sides. However, no damage to the cutting edge was observed even after processing about 3.5 million copies, and it was confirmed that the wear rate was extremely low. This is considered to be due to the effect of adding the residual stress of the compressor and improving the toughness by the ion implantation as described above.

[0014]

[Table 2]

Table 3 shows the measurement results of residual stress when various ions are implanted into various ceramic substrate materials. It can be seen that the compressive stress is 0.5 to 6 GPa in all cases. This compressive stress is generated by irradiation defects and volume expansion of the implantation surface layer due to the introduction of implanted ions,
It is said that the presence of this compressive residual stress contributes to the improvement of the toughness of ceramics. In order to confirm this, the surface of Example 1 was indented with a Vickers hardness tester,
When observing the indentation microscopically, minute cracks were generated at the corners of the indentation of untreated ceramic, whereas no cracks were generated in the ion-implanted ones.
It was confirmed that the ion implantation has an effect of improving toughness.

[0016]

[Table 3]

On the other hand, FIG. 4 shows the fracture toughness value Kic and the hardness of the injection surface when N ⁺ is injected into the yttrium-stabilized zirconia (ZrO ₂ ) ceramics of the same substrate as in Example 3. Although it depends on the irradiation dose, Kic is 1.2 to 1.5 times that of the non-implanter and the hardness is 1.2 to 1.
It can be seen that it will rise four times. In this abrasion test, the one using alumina ceramics as the base material of the blade was tested at a low linear pressure in consideration of the characteristics of alumina (low toughness). By studying, it is possible to obtain a blade that can withstand higher linear pressure.

[0018]

As described above, according to the present invention, since the blade portion of the blade is formed of the ceramics sintered material in which the front surface, the back surface and the side surface are ion-implanted, the blade is hard and thin and has a high toughness. Wear resistance, of course,
It has excellent peeling resistance and corrosion resistance, and provides good scraping performance and stable color tone of printed matter over a long period of time.

Therefore, it is not necessary to re-grind the blade, and since the replacement cycle is long, the time required to replace the blade, various operations required to reproduce the color tone, and the loss such as the increase of waste paper, etc., are drastically reduced.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, (a) is a side view and (b) is a plan view.

FIG. 2 is a wear comparison test diagram of the present invention and a conventional example.

FIG. 3 is a defect diagram of a conventional example, (a) is a side view, and (b) is a plan view.

FIG. 4 is the fracture toughness (K
ic) and the hardness increase diagram.

FIG. 5 is a cross-sectional view of a conventional example.

FIG. 6 is a sectional view of a conventional example.

FIG. 7 is a sectional view of a conventional example.

FIG. 8 is a sectional view of a conventional example.

[Explanation of symbols]

 1 blade 7 ion

Claims (1)

[Claims] 1. A scraping blade, characterized in that a blade portion of the blade is formed of a ceramics sintered material into which ions are injected on the front surface, the back surface and the side surface.