JP6423771B2 - Fixing device using stainless steel - Google Patents

Description

  The present invention relates to a fixing device provided with a thin-walled tubular fixing member using stainless steel, and in particular, a fixing sleeve for fixing toner onto a sheet by applying heat and pressure in a laser printer or a copying machine, or fixing. The present invention relates to a fixing device including a roller.

  The fixing method of laser printers and copiers has changed from the conventional roller fixing method to the film fixing method. In the conventional roller fixing method, since the heater inside the roller warms the roller, it is necessary to keep the heater on while printing is waiting. On the other hand, the fixing sleeve formed with a small thickness has high heat conduction efficiency, small heat capacity, and the heater operates only when it rotates, so that it is possible to save power and shorten the standby time. As the thin tubular body serving as the base layer of the fixing sleeve, a metal such as stainless steel or a resin such as polyimide is used. However, in order to save power and shorten standby time, it is preferable to use a metal such as stainless steel that has strength and a small heat capacity.

  The fixing sleeve is required to have circumferential flexibility and durability that can withstand deformation. When stainless steel is used as the base layer of the fixing sleeve, the thickness is manufactured to an extremely thin thickness of 20 to 50 μm. As a method for producing such an extremely thin metal tubular body, one using a spinning process is known (see Patent Document 1).

  An ultra-thin fixing sleeve using stainless steel has a small heat capacity (specific heat is smaller than that of a conventional aluminum fixing sleeve), and therefore has a good thermal response. In addition, an extremely thin fixing sleeve using stainless steel has a thin wall thickness, so that the temperature rise in the thickness direction of the fixing sleeve is quick. However, since the thermal conductivity is smaller than that of a conventional aluminum fixing sleeve, the axial thermal conductivity of the fixing sleeve is inferior. Furthermore, it is more likely that heat is taken away from the central portion in the axial direction to the recording paper side during paper feeding than the heat radiation from both ends in the axial direction. Accordingly, the temperature in the axial center of the fixing sleeve decreases and the temperature increases only at both ends in the axial direction, so the temperature in the axial direction of the fixing sleeve is not uniform, and so-called thermal unevenness of the fixing sleeve is a problem. It has become.

  As a method for eliminating the thermal unevenness of the fixing sleeve, there is a method in which the thickness (thickness) of the central portion in the axial direction of the fixing sleeve is reduced and the thickness (thickness) of both end portions in the axial direction is increased. is there. The central part in the axial direction is thin, so the heat capacity is small, and the temperature of the central part in the axial direction of the fixing sleeve is lowered during feeding, but the central part in the axial direction has a small heat capacity. Therefore, it is possible to reduce the heat unevenness of the fixing sleeve.

  Since the conventional aluminum fixing sleeve is relatively thick, the outer diameter side is cut or ground to create an inverted crown shape (the inner diameter side has a constant diameter, and the axial center thickness is set at both axial ends. The thickness of the fixing sleeve is less than that of the fixing sleeve. However, since the fixing sleeve using stainless steel is extremely thin, it is difficult to form the outer crown side into an inverted crown shape by cutting or grinding.

  The fixing sleeve using the stainless steel of Patent Document 2 is formed into an inverted crown shape by increasing the pressure applied to the rollers at both ends by bulging after spinning or by spinning. However, since the fixing sleeve of Patent Document 2 has a constant plate thickness (thickness), it is possible to prevent the occurrence of wrinkles and gloss unevenness of the recording paper, but it is not possible to reduce the heat unevenness of the fixing sleeve.

JP 2013-105057 A JP 2003-156554 A

  An object of the present invention is to form an ultra-thin fixing sleeve using stainless steel by spinning, and to make the plate thickness at the central portion in the axial direction into a reverse crown shape thinner than the thickness at both end portions in the axial direction. Another object of the present invention is to provide a fixing device using stainless steel in which the heat unevenness of the fixing sleeve is reduced.

According to the first aspect of the present invention, there is provided a method of manufacturing a fixing device using stainless steel, comprising: a thin-walled tubular fixing member that is heated by a heating element installed therein; A fixing device manufacturing method for fixing on a recording medium, wherein the fixing member includes a step of inserting a mandrel into an inner peripheral surface of a stainless steel cup-shaped tubular body, and a roller is pressed against the outer peripheral surface of the cup-shaped tubular body , Manufactured by a spinning process by controlling the radial and axial positions of the rollers, and gradually increasing the outer diameter and inner diameter of the cup-shaped tubular body from the axial center to both ends. The reverse crown shape of the outer diameter is larger than the reverse crown amount of the inner diameter.

The manufacturing method of the fixing device using the stainless steel of the second aspect of the present invention includes the step of pulling out the mandrel from the inner peripheral surface of the cup-shaped tubular body as the subsequent step of the spinning process in the first aspect of the present invention. It is characterized by that.

The fixing device manufacturing method using the stainless steel according to the third aspect of the present invention is the same as that of the first aspect of the present invention, in which the both ends of the cup-shaped tubular body are cut to form a base layer. It has the process of forming a tubular body.

The fixing device using the stainless steel manufactured by the manufacturing method of the present invention is such that the outer peripheral surface (outer diameter) and inner peripheral surface (inner diameter) of the tubular body are directed from the central portion in the axial direction to both ends by spinning. Since it is formed into a reverse crown shape that gradually increases and the thickness of the central portion in the axial direction is made thinner than the thickness of both end portions, the number of processing steps is reduced, and the heat unevenness of the fixing member is reduced. can do.

FIG. 1 is an explanatory diagram showing an outline of an image forming apparatus to which a fixing device manufactured by the manufacturing method of the present invention is applied. FIG. 2 is an explanatory view showing the fixing device using the stainless steel manufactured by the manufacturing method of the present invention in a sectional view. FIG. 3 is a process diagram showing a method for manufacturing a fixing member using the stainless steel of the present invention. 4A and 4B show a method for manufacturing a fixing roller according to an embodiment of the present invention. FIG. 4A is a longitudinal sectional view showing a cup-shaped tubular body forming step by deep drawing, and FIG. It is a perspective view which shows the cup-shaped tubular body. FIG. 5 shows a post-process of FIG. 4, FIG. 5 (a) is an explanatory view showing a process of inserting a mandrel into the inner peripheral surface of the cup-shaped tubular body of FIG. 4 (b), and FIG. It is explanatory drawing which shows the process of pressing a roller on the outer peripheral surface of a tubular shape and performing a spinning process. FIG. 6 is an explanatory view showing the end of the step of FIG. 5B and showing a state in which the spinning process of the cup-shaped tubular body is completed. FIG. 7 is an explanatory view showing a post-process of FIG. 6 and a process of pulling out the mandrel from the inner peripheral surface of the cup-shaped tubular body after the spinning process of FIG. 6 is completed. FIG. 8 is an explanatory diagram showing a process of forming a tubular fixing roller by cutting both ends of the cup-shaped tubular body after the spinning process is completed, showing the post-process of FIG. FIG. 9 shows measurement data of the outer diameter, plate thickness, and inner diameter of a tubular fixing roller having both ends cut, and is an explanatory diagram showing measurement data and average values of three fixing rollers. FIG. 10 is a line graph showing an average value of the outer diameter measurement data and the inner diameter measurement data of FIG. FIG. 11 is a calculation formula for calculating the outer diameter reverse crown amount, the inner diameter reverse crown amount, and the plate thickness difference from the average values of the measurement data in FIG.

[Overview of image forming apparatus]
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing an outline of an image forming apparatus to which a fixing device manufactured by the manufacturing method of the present invention is applied. The present invention relates to the fixing device 9. First, an outline of the configuration of the image forming apparatus 1 to which the fixing device 9 is applied will be described. The image forming apparatus 1 has various forms and is well known. For example, the image forming apparatus 1 related to a laser printer will be described. The image forming apparatus 1 includes a main body 2, an exposure unit 3, a photoconductor 4, a transfer unit 5, a tray 6, a paper feed unit 7, a registration roller 8, a fixing device 9, and the like. Since the function and configuration of each element are known, detailed description thereof is omitted. Next, an outline of the operation of the image forming apparatus 1 will be described.

  At the time of copying, the photosensitive member 4 is irradiated with laser light A of an image to be copied from the exposure unit 3. A toner image is formed by the toner 11 through charging, exposure, and development processes while rotating the photosensitive drum of the photosensitive member 4. The toner 11 is obtained by encapsulating a colorant and wax in particles, and a toner image is formed on the photoreceptor 4 through the above-described steps. This toner image is transferred to the paper 12 sent from the paper feeding unit 7 by the registration roller 8 in the transfer unit 5 through a transfer roller provided opposite to the photoconductor 4.

  The sheet 12 that has passed through the transfer unit 5 is sent to the fixing device 9. In the fixing device 9, the paper 12 is sent while being sandwiched between the fixing roller 13 and the pressure roller 14, and the toner image is fixed on the paper 12 by heat and pressure. The fixed sheet 12 is discharged as an output image to the tray 6 in a flow indicated by an arrow. Basically, copying with a laser printer is performed by the above-described process.

Next, the fixing device 9 will be described. FIG. 2 is an explanatory view showing the fixing device 9 using the stainless steel manufactured by the manufacturing method of the present invention in a sectional view. A fixing device 9 to which the present invention is applied basically includes a fixing roller (fixing member) 13, a pressure roller 14, a halogen heater that is a heating element 15, and the like. This apparatus is configured to press the pressure roller 14 against the thin tubular fixing roller 13 and fix the toner image on the paper 12. First, the fixing roller 13 will be described. The fixing roller 13 is heated by a halogen heater which is a heating element 15 installed in the fixing roller 13.

  The fixing roller (fixing member) 13 is formed of stainless steel having a base layer thickness of 100 to 300 μm. Instead of the fixing roller 13 having a relatively large thickness, a fixing sleeve (fixing film as a fixing member) formed of ultrathin stainless steel having a thickness of 20 to 50 μm may be used. If an extremely thin fixing sleeve is used, a nip portion having a predetermined nip width is formed between the pressure roller 14 and the heating element 15, the fixing sleeve is pressed, and only the nip portion is heated. Heat fixing becomes possible.

[Method for Manufacturing Fixing Roller 13]
FIG. 3 is a process diagram showing a method for manufacturing a fixing member using the stainless steel of the present invention. FIG. 4 shows a method for manufacturing a fixing roller according to an embodiment of the present invention. FIG. 4A is a longitudinal sectional view showing a step of forming a cup-shaped tubular body by deep drawing in STEP 1 of FIG. b) is a perspective view showing a molded cup-shaped tubular body 200. FIG. A fixing sleeve made of ultra-thin stainless steel having a wall thickness of 20 to 50 μm can also be manufactured by the same manufacturing method as the fixing roller. As shown in FIG. 4A, a stainless steel thin plate 100 such as SUS304 is deep-drawn with a female die 101 and a punch 102 to form a cup-shaped tubular body 200 shown in FIG. 4B.

  FIG. 5 shows the post-process of FIG. 4, FIG. 5A shows the process of STEP 2 of FIG. 3, and is an explanatory view showing the process of inserting the mandrel 300 into the inner peripheral surface 201 of the cup-shaped tubular body 200. . As shown in FIG. 5, the mandrel 300 is fitted into the inner peripheral surface 201 of the cup-shaped tubular body 200, and the mandrel 300 is rotated to rotate the cup-shaped tubular body 200.

  FIG. 5B shows the process of STEP 3 of FIG. 3, and is an explanatory view showing the process of performing the spinning process by pressing the roller 301 against the outer peripheral surface 202 of the cup-shaped tubular body 200. Spinning is performed by simultaneously controlling the radial and axial positions of the roller 301 in two axes. The cup-shaped tubular body 200 is plastically deformed in the radial direction and the axial direction of the cup-shaped tubular body 200 to become thin, and is elongated in the axial direction. The inner peripheral surface (inner diameter) 201 and the outer peripheral surface (outer diameter) 202 of the cup-shaped tubular body 200 are formed in an inverted crown shape that gradually increases from the central portion in the axial direction toward both end portions.

  The positions of the rollers 301 in the radial direction and the axial direction are simultaneously controlled so that the reverse crown amount of the outer peripheral surface (outer diameter) 202 is larger than the reverse crown amount of the inner peripheral surface (inner diameter) 201. FIG. 6 is an explanatory view showing the end of the process of FIG. 5B and showing a state in which the spinning process of the cup-shaped tubular body 200 is completed. FIG. 7 is an explanatory view showing the process of drawing the mandrel 300 from the inner peripheral surface 201 of the cup-shaped tubular body 200 after the spinning process of FIG. .

  FIG. 8 is an explanatory view showing the step of STEP 5 in FIG. 3 and the step after FIG. 7 and showing the step of forming a tubular fixing roller by cutting both ends of the cup-shaped tubular body 200 after the spinning process. . As shown in FIG. 8, a stainless steel tubular body having a thickness of 100 to 300 μm and serving as a base layer of the fixing roller 13 is obtained by cutting both ends of the cup-shaped tubular body 200 after the spinning process with cutting tools 302 and 302. 400 is obtained. It is also possible to manufacture a stainless steel tubular body 400 having a thickness of 20 to 50 μm and being applicable to a fixing sleeve by spinning in the same process.

  FIG. 9 shows measurement data of the outer diameter, plate thickness (thickness), and inner diameter of the stainless steel tubular body 400 serving as the base layer, and the stainless steel tubular body (fixing roller) 400 (No. It is explanatory drawing which shows the measurement data (The length of an axial direction is measured at an interval of 10 mm), and the average value of three. FIG. 10 is a line graph showing the average value of the three outer diameter measurement data and inner diameter measurement data of FIG. FIG. 11 is a calculation formula for calculating the outer diameter reverse crown amount, the inner diameter reverse crown amount, and the plate thickness difference (thickness difference) from the measurement data of the three average values in FIG.

  The nominal dimensions of the stainless steel tubular body 400 as the base layer shown in FIGS. 8 to 10 are an outer diameter of 20 mm, a plate thickness (thickness) of 200 μm, and an axial length of 260 mm. As shown in FIGS. 8 to 10, the outer peripheral surface (outer diameter) 402 and the inner peripheral surface (inner diameter) 401 of the stainless steel tubular body 400 serving as the base layer gradually move from the central portion 400 </ b> C in the axial direction toward both ends. It is formed in an inverted crown shape that becomes larger. As shown in FIG. 11 (1), the reverse crown amount of the outer diameter is 267 μm, and as shown in FIG. 11 (2), the reverse crown amount of the inner diameter is 162 μm, and the reverse crown amount of the outer diameter is the reverse crown amount of the inner diameter. It is formed larger than. The plate thickness (thickness) is 136 μm (tD2) at the axial center 400C, 191 μm (tD1) and 186 μm (tD3) at both ends in the axial direction, and the central thickness in the axial direction is thin. Small heat capacity. Accordingly, the temperature of the central portion in the axial direction of the fixing roller 13 is lowered during paper feeding, but since the heat capacity is small in the central portion in the axial direction, the temperature in the central portion in the axial direction is easily increased, and the heat of the fixing roller 13 is increased. Unevenness can be reduced.

The fixing device using stainless steel manufactured by the manufacturing method of the present invention is a process of forming a stainless steel tubular body 400 as a base layer by thinning the cup-shaped tubular body 200 by spinning. The outer peripheral surface (outer diameter) 402 and the inner peripheral surface (inner diameter) 401 are formed in an inverted crown shape that gradually increases from the central portion 400C in the axial direction toward both ends. As a result, since the plate thickness at the central portion in the axial direction is formed thinner than the plate thickness at both end portions, the number of processing steps is reduced, and the thermal unevenness of the fixing member can be reduced at low cost.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 2 ... Main body 3 ... Exposure part 4 ... Photoconductor 5 ... Transfer part 6 ... Tray 7 ... Paper feed part 8 ... Registration roller 9 ... Fixing device 11 ... Toner 12 ... Paper 13 ... Fixing roller 14 ... Pressure Roller 15 ... Heating element A ... Laser beam 100 ... Stainless steel thin plate 101 ... Female mold 102 ... Punch 200 ... Cup-shaped tubular body 201 ... Inner peripheral surface 202 ... Outer peripheral surface 300 ... Mandrel 301 ... Roller 302 ... Cut-off tool 400 ... Base layer Stainless steel tubular body 401 ... inner peripheral surface 402 ... outer peripheral surface 400C ... central portion in the axial direction

Claims (3)

An image forming apparatus for copying with toner, comprising a thin tubular fixing member heated by a heating element installed therein, and a method of manufacturing a fixing apparatus for heating and fixing a toner image on a recording medium,
The fixing member is
Inserting a mandrel into the inner peripheral surface of a stainless steel cup-shaped tubular body;
A roller is pressed against the outer peripheral surface of the cup-shaped tubular body, and is manufactured in a step of performing spinning by controlling the radial and axial positions of the roller,
An outer diameter and an inner diameter of the cup-shaped tubular body are formed in an inverted crown shape that gradually increases from the central portion in the axial direction toward both ends, and the reverse crown amount of the outer diameter is larger than the reverse crown amount of the inner diameter. A method for manufacturing a fixing device using stainless steel, characterized in that it is formed large. In the manufacturing method of the fixing device using the stainless steel according to claim 1 ,
A method of manufacturing a fixing device using stainless steel, comprising a step of pulling out the mandrel from an inner peripheral surface of the cup-shaped tubular body as a subsequent step of the spinning process. In the manufacturing method of the fixing device using the stainless steel according to claim 1 ,
A fixing device using stainless steel, comprising a step of forming a stainless steel tubular body as a base layer by cutting both ends of the cup-shaped tubular body as a subsequent process of the spinning process Manufacturing method.

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