JPS63208892A - Production of roller for pressure fixing - Google Patents

Abstract

PURPOSE:To permit reduction of the size and weight of a pressure fixing roller while sufficient rigidity is maintained and to obtain the roller adequate for the assembly of the entire part of a device to a compact unit by calcining a hollow cylindrical multi-layered molding made of ceramics and forming a hand drum-shaped cylindrically curved surface by differences in the rates of shrinkage of the respective layers. CONSTITUTION:The hollow cylindrical multi-layered molding integrated with plural cylindrical moldings made of ceramics having different densities is prepd. Such multi-layered molding is calcined to form the pressure fixing roller having the hand drum-shaped cylindrically curved body by the differences in the shrinkage rates of the respective layers. Since this pressure fixing roller is hollow and consists of the calcined ceramic body, the roller can be formed to the smaller size and weight while the sufficient rigidity is maintained. Since the roller has the hand drum shape, a uniform pressure can be exerted over the entire part of recording paper at the time of fixing, by which the uniformity of fixing is attained and the copied image, etc., having high quality are obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method of manufacturing a pressure fixing roller for office equipment, particularly a pressure fixing roller for a copying machine.

[Conventional technology]

As a typical fixing method for copying machines and the like, a method using a heat fixing roller or a pressure fixing roller is known. Among these, the heat fixing roller requires a large amount of electric power as a heat source. Also, warm-up (the time from when the switch is turned on until the actual copying is possible, that is, the time it takes for the heater to warm up)
There are disadvantages such as time consuming. Therefore, recently, a fixing method using a pressure fixing roller has been attracting attention. This method involves passing recording paper with toner or other objects attached between a pair of rollers that are pressed together under high pressure.
This is a method of fixing an image on an object. The pressure fixing port used in this method is shown in FIG. A pair of rollers are
As shown in the figure, the rollers are generally slightly crossed so that even pressure is applied to the recording paper passing between the rollers and to prevent wrinkles from forming on the paper.

(Problems to be Solved by the Invention) Since such a pair of rollers is brought into contact with each other under high pressure, it is necessary to increase the rigidity. However, if this condition is to be met, the rollers are generally made of steel, which has the disadvantage that their external dimensions become large, resulting in an increase in the size and weight of the entire device.

Even if there is a ceramic pressure fixing roller that eliminates these drawbacks, since it is a single cylindrical roller, there will be uneven fixing due to uneven pressure on the recording paper during fixing.
However, there remained the problem of deterioration in the quality of copied images.

In order to make such a roller into a chain-like roller suitable for uniform fixing, a considerable amount of complicated machining such as cutting would have to be carried out, which would be costly in terms of time, labor, and cost.
Many problems arise in terms of accuracy.

The purpose of the present invention is to make the entire device more compact;
Moreover, it is an object of the present invention to provide a method for easily manufacturing a pressure fixing roller that can achieve uniform fixation and improve the quality of copied images, etc., without using any complicated machining such as cutting.

(Means for solving the problem) The above purpose is to produce a hollow cylindrical multilayer molded body in which a plurality of ceramic cylindrical bodies having different densities are integrated, and then to sinter the multilayer molded body. This can be achieved by a method of manufacturing a pressure fixing roller, in which the roller has a cylindrical curved surface in the shape of a chain due to the difference in shrinkage rate of each layer.

The above-mentioned multilayer molded body typically combines (a) a core mold and a pressurizing mold a that maintains a cylindrical space A around the core mold, and after filling the cylindrical space A with ceramic powder, pressurizing the pressurizing mold a. (b) After installing a pressure mold around the molded product formed by the above operation to maintain the cylindrical space B, the cylindrical space is B was filled with ceramic powder, and then the pressure mold was pressed mainly with a force weaker than the previous pressing force, so that the molded body formed by the above operation and the newly formed molded body were integrated. The pressing molds a and b may be the same or different. Furthermore, when the operation (b) is performed more than once, the pressure mold used each time may be the same or different.

The method for manufacturing a pressure fixing roller according to the present invention has been completed by focusing mainly on the following points.

As shown in Figure 1, a ceramic powder material 4 is pressed using a uniaxial press using a mold consisting of a die 1, an upper punch 2, and a lower punch 3 to form a prismatic molded body. Due to contraction of the body, the lower punch 3 side that is pressurized generally becomes concave, and the prismatic fired body takes on an arch shape. This phenomenon is considered to be mainly caused by the density distribution during molding. Therefore, when producing molded bodies, a double-wheel press is usually used to ensure uniform density. However, the method for manufacturing the pressure fixing roller of the present invention is different from this usual method, and was conceived because deformation with a white surface occurs due to firing in a -axial press.
It is complete. That is, the method of the present invention as summarized above takes advantage of such a modification and applies this modification to unexpected fields.

Next, the reason why the pressure fixing roller produced by the method of the present invention has a cone-shaped curved surface will be explained based on experimental data that formed the basis of this manufacturing method.

When a ceramic powder material is pressure-molded using a uniaxial press using a mold, as shown in FIG. 2, when the compacting pressure is increased, the powder becomes densely packed and the density of the compact increases. Therefore, by changing the molding pressure, molded bodies with different densities can be produced. When the molded bodies having different densities thus formed are fired at a constant temperature, it can be seen that the higher the density of the molded body, the higher the density of the fired body, as shown in FIG. Here, when calculating the shrinkage rate, the fourth
As shown in the figure, the higher the compact density, the smaller the shrinkage rate.

From the above results, as shown in FIG. 5, as the molding pressure increases, the shrinkage rate during firing decreases.

Therefore, if a molded body is made in which a plurality of layers 5 and 6 with different densities are integrated as shown in FIG.
As shown in the figure, the fired body can have a concave surface. Therefore, if the molded body is made into a multilayer cylindrical body having different densities, it becomes possible to obtain a chain-shaped pressure fixing roller as shown in FIG. 8 by firing.

Next, the method for manufacturing the pressure fixing roller of the present invention will be explained in more detail using representative examples. 9 as the first step
As shown in the figure, a ceramic powder material 4 to which additives such as a binder have been added as required is filled into a mold and sealed. That is, first, the cylindrical body 8 (
A typical example of a core mold) is inserted, and a cylindrical hollow thin-walled rubber mold 9 is fitted into the lower lid 7 for compression molding. Subsequently, after sealing the gap 10 between the compression molding lower lid 7 and the rubber mold 9 with tape, this is placed on a vibrating plate, and the ceramic powder material 4 is filled while applying vibration. Next, after covering with the compression molding top lid 11, the gap chamber 2 formed between the compression molding top lid and the rubber mold is sealed with tape. In addition, examples of ceramic materials that can be used include alumina,
Examples include zirconia, silicon nitride (5lain), silicon carbide, and composite materials thereof.

As a second step, the thus sealed filling is pressurized using a cold isostatic press, and then the pressurized molded body is machined into a cylindrical shape to form a molded body A.

In the next third stage, processing is performed as shown in FIG. That is, first, the cylindrical body 8 is reinserted into the lower lid 7 for compression molding, and
The rubber mold 9 is also fitted into the compression molding lower lid 7 again. After that, a gap 1 is formed between the compression molding lower cover 7 and the rubber mold 9.
Seal 0' with tape. In this mold with only the top open,
The molded body A produced in the second step is inserted, and then the space between the rubber mold 9 and the molded body A is filled with ceramic powder material 4' while being vibrated. Next, after covering with the upper lid 11 for compression molding, the gap 12' created between the upper lid 11 for compression molding and the rubber mold 9 is sealed with tape.

In the fourth stage, a cold isostatic press equipment is used to
Apply a lower pressure than that used in the step. The resulting molded body is subjected to cylindrical processing to obtain a cylindrical molded body with a two-layer structure.

In the fifth step, the molded body is fired and, if necessary, subjected to polishing treatment, etc., to obtain a pressure fixing roller.

Since the pressure fixing roller manufactured according to the present invention as described above is hollow and made of a fired ceramic body, it can be made smaller and lighter while maintaining sufficient rigidity. [Note that the hollow shape is because the Young's modulus of ceramics is larger than that of conventional steel, and the rigidity of the roller is proportional to (4th power of the outer diameter - 4th power of the inner diameter). It is almost impossible to cause a decrease in stiffness. ] In addition to the above-mentioned advantages, since the pressure fixing roller manufactured according to the present invention is not cylindrical but has a cylindrical shape, it is possible to apply even pressure to the entire recording paper during fixing.
Uniform fixation can be achieved and high quality copied images can be obtained.

The most important point of the method of the present invention, which can manufacture a pressure fixing roller having such many advantages, is that it also has the following advantages. In other words, by calculating the amount of firing shrinkage of the prototype shaped body and adjusting the molding pressure during actual molded body production accordingly, the fired body (pressure fixing roller) with the desired cone-like curved surface is formed. The advantages are that the body can be easily made, and that the fired body itself can be easily set to a curved surface closer to the final dimension. As a result, pressure fixing rollers with different shapes can be manufactured from one rubber mold, the overall manufacturing cost can be reduced, almost no machining is required, and processing costs, labor, etc. can be greatly reduced.

In the manufacturing method of the present invention, it is preferable that the physical properties of each layer of the molded product, other than the density, be as similar as possible to prevent distortion, cracking, cracks, etc. from occurring during firing. Furthermore, if the densities of the respective layers of the molded body are too different, distortion etc. are likely to occur as well, so it is also effective to increase the number of layers and gradually change the density difference between the layers.

In the above manufacturing example, a multilayer molded body with different densities was molded by applying different molding pressures and then fired. The present invention may be carried out by utilizing the difference in shrinkage during firing of the layers.

In addition, in the manufacturing method of the present invention, after the fifth step, the surface of the pressure fixing roller is of course coated with electroless plating, thermal spraying, etc.
Treatments such as vapor deposition and resin coating may also be applied.

[Example] Example 1 A pressure fixing roller of the present invention was manufactured using a mold as shown in FIG. 9.10 and the method described above. The ceramic powder material used was Showa Light Metal Alumina 160.
It is 3GT3. To this 100 parts, 1 part of PVA, 3 parts of acrylic acid binder, and 1 part of stearic acid binder were added.

The outer diameter of the cylindrical body used was 23.5 mm, and the inner diameter of the rubber mold was 57 mm.
■-. When the mold is sealed, the distance between the top and bottom lids is 3051
■It is.

The pressure of the cold isostatic press was 2t/C■2.
The second time was 1 t/cm2. The firing conditions are as shown in Fig. 1t. The thickness of the fired body was 16 m1, and the difference in diameter between the narrowest part near the center of the roller and the thickest part near the edge was 2.411.

(Effects of the Invention) As explained in detail above, according to the method of the present invention, it is possible to reduce the size and weight while maintaining sufficient rigidity, and it is possible to reduce the size and weight of the entire device. A chain-shaped pressure fixing roller that can also improve quality can be easily obtained.

In addition, the method of the present invention has the advantage of significantly reducing the cost of molds used during production, reducing overall costs, and requires less final processing, so it is less expensive and labor-intensive than conventional methods. , it has the advantage of being able to achieve significant improvements in terms of accuracy and time.

[Brief explanation of the drawing]

Figure 1 is a diagram showing how uniaxial pressing is performed, the second group is a diagram showing the relationship between compacting pressure and compact density, Figure 3 is a diagram showing the relationship between compact density and fired compact density, and Figure 4 is a diagram showing the relationship between compact compact density and fired compact density. A diagram showing the relationship between molded body density and shrinkage rate during firing, Figure 5 is a diagram showing the relationship between molding pressure and shrinkage rate during firing, and Figure 6 is a diagram showing a molded body consisting of two layers with different densities. FIG. 7 is a diagram showing the shape of the molded body of FIG. 6 after firing, FIG. 8 is a schematic diagram of a pressure fixing roller manufactured according to the present invention, and FIGS. 9 and 10 are respectively according to the present invention. Figure 11 is a diagram showing the process of manufacturing the pressure fixing roller in Example 1. Figure 11 is a diagram showing the firing conditions in Example.
FIG. 2 is a diagram showing how the pressure fixing roller is installed. 1: Die 2: Upper punch 3: Lower punch 4.4': Ceramic powder material 5.6: Layer 7 2 Lower cover for compression molding 8: Cylindrical body ゛9; Rubber mold 10.10', 12.12': Gap 11: Upper lid for compression molding

Claims (1)

[Claims] 1) A hollow cylindrical multilayer molded body is produced by integrating a plurality of ceramic cylindrical bodies with different densities, and then the multilayer molded body is fired to determine the shrinkage rate of each layer. Depending on the difference, the roller has a cylindrical curved surface,
A method of manufacturing a pressure fixing roller. 2) The production of the hollow cylindrical multilayer molded body is performed as follows (a)
A method of manufacturing a pressure fixing roller according to claim 1, which is carried out by sequentially carrying out the steps of (b) and (b). (a) It has a core mold and a pressure mold a that maintains a cylindrical space A around it, and after filling the cylindrical space A with ceramic powder, pressurizes the pressure mold a to form a hollow cylindrical molded body. A step of carrying out a molding operation, and (b) ``After installing a pressurizing mold b that maintains a cylindrical space B around the molded object made by the above operation, filling the cylindrical space B with ceramic powder, and then , an operation of pressurizing the pressurizing mold b to produce a molded object in which the molded object formed by the above operation and the newly formed molded object are integrated.''
A process in which the process is performed more than once. 3) The method of manufacturing a pressure fixing roller according to claim 2, wherein the same ceramic powder is used for all the ceramic powders.