JPH0151837B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims to improve the surface temperature distribution of a heat fixing roll used in an electrophotographic copying device, particularly a heat fixing roll incorporating a heating element, and to increase the strength of the shaft portion of the roll. The present invention relates to a heat fixing roll having a shaft portion formed under pressure.

For example, in an electrophotographic copying device, it is common to electrophotographically form an image using thermoplastic powder (toner) on a photoreceptor, transfer the toner image onto transfer paper, and then fix it. It is a copying process,
As a method for fixing this toner image, a fixing method using a contact heating roll is often used. A fixing method using a contact heating roll is also used in dry electrostatic printers.

In this heat fixing method, a roll whose surface is coated with a layer of heat-resistant release material such as silicone rubber is brought into contact with a heat-resistant and flexible pressure roll while applying a constant pressure. is passed through the paper to be fixed and fixed.

An example of a heating roll used in this fixing method is one that uses a cylindrical metal material with high thermal conductivity and is equipped with a heating element inside the heating roll. Some are provided in the center, while others are installed as a heat generating layer inside the cylinder. The conventionally known and practically used structure of such a heating roll is schematically shown in FIG. In this heating roll, the roll base 1 is made of aluminum or aluminum alloy, and the joint pipes 2 made of the same or different metal as the roll base 1 or non-metallic material as the case may be are joined to both ends of the roll base 1. A heating roll with a similar structure is used.
A heating element 3 is provided inside the heating roll, and the surface of the roll base 1 is coated with a layer 4 of a heat-resistant release material (for example, silicone rubber).

According to the structure of the conventional heating roll as described above,
The temperature at both ends of the roll is lower than the temperature at the center of the roll due to the heat capacity of the joining joint and heat dissipation from the joining joint, and the heat loss due to heat radiation from the joining joint is large, causing excessive heat power. will be consumed. One possible way to solve these problems of temperature distribution and heat loss is to use a metal with relatively low thermal conductivity as the material for the joining joint, but the strength of the joint against intermittent heat and pressure during fixing is limited. It has the disadvantage of being weak in some areas. In other words, it is possible to use stainless steel as a metal with relatively low thermal conductivity as the material for the joining joint, but for joining the stainless steel joint and the roll base (made of aluminum or aluminum alloy), for example, argon welding,
There are methods such as press-fitting and pinning, but in the case of argon welding, metals with different coefficients of thermal expansion are welded, so the welded part may peel off due to intermittent heat and pressure. In addition, in the case of press-fitting, there is a difference in the diameter of the shaft and roll due to the difference in thermal expansion coefficient, causing the shaft to be separated, and in the case of pinning, there is no possibility of wobbling during use, and the joint strength is not satisfactory. I couldn't get it. Further, even if the two are joined by a method that utilizes metal melting through frictional contact (hereinafter referred to as a pressure welding method), since the melting points of the stainless steel and the roll base are different, only mechanical joining can be performed. As a result, due to thermal insulation, gaps were created at the joint surfaces due to the difference in thermal expansion coefficients between stainless steel and aluminum, and eventually they separated, making it impossible to obtain a joint that could withstand long-term use.

The present invention was made in view of the above circumstances, and its purpose is to use stainless steel, which has a relatively low thermal conductivity, for the shaft portion of the heating roll.
The stainless steel shaft and the aluminum or aluminum alloy roll base can be firmly joined,
The present invention provides a heat fixing roll that has a longer life than conventional heat fixing rolls.

An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a cross-sectional view in the roll axis direction showing the structure of an embodiment of the heat fixing roll of the present invention.

In FIG. 2, the heating roll main body has a structure consisting of a cylindrical tube 11 made of aluminum or aluminum alloy, and joining joints 12 made of die-cast aluminum or aluminum alloy firmly fixed to both ends of the cylindrical tube 11 by pressure welding, A stainless steel core 13 is cast into the aluminum or aluminum alloy die-cast joining joint 12 to form a shaft portion. Here, the pressure welding method used for fixing the cylindrical pipe 11 and the joining joint 12 is a joining method known to those skilled in the art, which uses melting due to frictional contact to fuse the two as described above. . Also at this time, the cylindrical tube 1
Since the joining joint 1 and the joining joint 12 are made of the same material, their melting points are the same, and a strong joined state that can withstand long-term use can be obtained in this part. Further, a heating element 18 such as an infrared lamp or a nichrome wire is provided inside the cylindrical tube 11, and the surface of the cylindrical tube 11 is coated with a layer 15 of heat-resistant mold release material such as silicone rubber. There is.

The core metal 13 cast into the aluminum or aluminum alloy die-cast joining joint 12 is made of stainless steel pipe material by cold forging, press working, etc.
As shown in FIGS. 6 to 6, a flange portion 14 that is cast into a die cast is processed to have a rotation-preventing shape.

3 to 6 show the shape of the core bar 13.
In the figure, circular holes 15 and semicircular notches 16 are provided in the flange portion 14, and a rotation preventing function is produced by inserting an aluminum or aluminum alloy die-cast member into the circular holes and semicircular notches.

Further, in FIG. 4, cutout recesses 17, 17 are provided in a part of the flange portion 14 to form a rotation preventing shape. Further, in FIG. 5, a rotation stopper is formed by cutting out a part of the circumference of the flange portion 14. Further, in FIG. 6, a portion of the flange portion 14 is bent at a predetermined angle to form a rotation stopper. Note that the shape of the rotation stopper of the flange portion of the core metal 13 is not limited to the shapes shown in FIGS. 3 to 6 above, and various modifications such as an ellipse, tooth shape, outer diameter knurling, etc. are possible.
Further, it is possible to use various shapes such as a combination of the shapes shown in FIGS. 3 to 6.

By casting the core metal 13 having such a shape into the die casting 12, the core metal 13 and the die-cast joining joint 12 are firmly connected, and a shaft portion is formed that does not cause rotational misalignment or play in connection due to rotation.

According to the structure described above, since stainless steel, which is a metal with relatively low thermal conductivity, is used for the shaft, heat loss due to heat diffusion from the shaft can be minimized, and Even though stainless steel is used, the bond between the dissimilar metal of aluminum or aluminum alloy becomes stronger when the core metal is die-cast. Furthermore, since the joining joint made of aluminum or aluminum alloy die-cast with a cored metal cast inside and the aluminum or aluminum alloy cylindrical tube are joined by pressure welding, the roll base and shaft are integrally joined. It has a structure that can withstand long periods of intermittent heat and pressure.

EXAMPLE A more detailed example of the heat fixing roll of the present invention having the structure shown in FIG. 2 will be described.

Chemical composition, Si0.2-0.6, Fe0.35 or less, Cu0.1 or less, Mn0.1 or less, Mg0.45-0.9, Cr0.1 or less,
A third stainless steel pipe is installed at both ends of a cylindrical tube 11 with a diameter of φ40 mm made of an aluminum alloy material with a composition of Zn 0.1 or less, Ti 0.1 or less, others 0.15 or less, and the remainder Al.
Chemical composition of the core metal 13 pressed into the shape shown in the figure: Cu0.2 or less, Si0.3 or less, Mg4.0~
8.5, Zn0.1 or less, Fe1.8 or less, Mn0.3 or less, Ni0.1
Below, die casting 12 of an aluminum alloy material having a composition of Sn0.1 or less and the balance of Al
Rotate the cast shaft at 2400 rpm and apply pressure to 1 cm ²
They were joined by pressure welding under the conditions of 5 kg per unit and a frictional heat generation feed time of 6 to 7 seconds to form the shape shown in Figure 2.
Further, the layer 15 of heat-resistant mold release material was formed of silicone rubber, and an infrared lamp 18 was installed as a heating element inside the tube.

Attach this heating roll to a pressure heat fixing device,
Pressure was applied using a pressure roller and the fixing operation was repeated at a temperature of 230 degrees Celsius, but there was no damage or cracking in the shaft despite long-term use. In addition, power consumption was reduced and the temperature distribution on the roll surface was uniform, achieving extremely excellent effects that eliminated the drawbacks of the conventional method.

As described above, according to the present invention, since stainless steel is used for the core of the shaft, heat diffusion from the shaft of the heat fixing roll is reduced, temperature distribution on the roll surface is made uniform, and power consumption is reduced. can be reduced. Furthermore, it has the advantage that it is less likely to be scratched during the work process, making it easier to manage the work, and it also has the advantage that a wide range of materials can be used for the core metal receiving member. In addition, the aluminum or aluminum alloy die-cast shaft, in which the core metal is cast into the die-cast, is connected to both ends of the aluminum or aluminum alloy cylindrical tube by pressure welding to form an integral structure. It has the advantage of being able to withstand sufficient pressure.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a heating roll incorporating a conventional heating element in the roll axis direction, FIG. 2 is a cross-sectional view of the heat fixing roll of the present invention in the roll axis direction, and FIGS. 3 to 6 are each a cross-sectional view of the present invention. It is a figure showing the shape of the core metal used for. 11...Cylindrical pipe, 12...Die-cast joining joint, 13...Core metal.

Claims (1)

[Claims] 1. A heat fixing roll characterized in that a shaft portion is formed by pressure-welding joining joints made of aluminum or aluminum alloy die-casting with a stainless steel core cast into both ends of a cylindrical aluminum or aluminum alloy roll. .