Fixing device

Abstract

It was necessary to ensure thermal insulation using only sliding components, without using any other thermal insulation materials. [Solution] The fixing device according to this application comprises an endless, rotatable belt for heating a recording material; a contact member that contacts the outer circumferential surface of the belt; a pad member positioned on the inner circumferential surface of the belt, opposite the contact member with the belt in between, and forming the nip portion between the belt and the contact member; the pad member comprises a sliding member that slides against the inner circumferential surface of the belt and a holding member that holds the sliding member, wherein the sliding member has a plurality of protrusions on the surface that slides against the inner circumferential surface of the belt and a plurality of recesses on the surface that contacts the holding member.

Description

Technical Field

[0001] The present invention relates to a fixing device suitable for an image forming apparatus using electrophotographic technology such as a printer, a copier, a facsimile machine, or a multifunction peripheral.

Background Art

[0002] An image forming apparatus includes a fixing device that fixes a toner image on a recording material by applying heat and pressure to the recording material on which an unfixed toner image is formed.

[0003] As a fixing device, one including an endless fixing belt, a roller (pressure roller) that contacts the outer peripheral surface of the fixing belt, a sliding member that presses the fixing belt from the inner peripheral surface toward the roller side, and a stay that supports the sliding member is used.

[0004] In this fixing device, a fixing nip portion formed between the fixing belt and the roller sandwiches and conveys the recording material in a heated and pressurized state, whereby the toner image is fixed on the recording material.

[0005] The sliding member presses the fixing belt from the inner peripheral surface side toward the fixing nip portion in order to secure the nip pressure in the fixing belt.

[0006] In a belt-type fixing device, in recent years, there has been a demand for further shortening of the time required to reach a predetermined temperature (reload temperature) at which printing is possible from a normal temperature state such as when the power is turned on, that is, the warm-up time.

[0007] Also, shortening of the time (first print time) from when a print request is received until the printing operation is performed after printing preparation and the paper discharge is completed is desired.

[0008] Therefore, conventionally, as disclosed in Patent Document 1, a method has been taken in which a heat insulating member is provided to improve the heat insulation from the sliding member to other components such as a stay.

Prior Art Documents

Patent Documents

[0009] [Patent Document 1] Japanese Patent Publication No. 2016-053632 [Overview of the project] [Problems that the invention aims to solve]

[0010] However, in the conventional example described in Patent Document 1 above, even if an insulating material is used, heat escape from the sliding member to the stay and other materials remains, resulting in problems such as increased power consumption during long-term continuous operation and a reduced heater lifespan.

[0011] This invention has been made in view of these points, and its purpose is to ensure thermal insulation using only sliding members, without using thermal insulation members. [Means for solving the problem]

[0012] To achieve the above objective, the fixing device according to this application is a fixing device for fixing a toner image supported on a recording material at a nip portion to the recording material, comprising: an endless, rotatable belt for heating the recording material; a contact member that contacts the outer circumferential surface of the belt; a pad member disposed on the inner circumferential surface of the belt, facing the contact member with the belt in between, and forming the nip portion between the belt and the contact member; the pad member comprising a sliding member that slides against the inner circumferential surface of the belt and a holding member that holds the sliding member, wherein the sliding member has a plurality of protrusions on the surface that slides against the inner circumferential surface of the belt and a plurality of recesses on the surface that contacts the holding member. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a component configuration that can improve the thermal insulation of a sliding member by reducing the contact area between the sliding member and other members and forming an air layer. [Brief explanation of the drawing]

[0014] [Figure 1] Schematic diagram showing the configuration of the image forming apparatus according to the present embodiment [Figure 2] Schematic diagram showing the fixing device according to the present embodiment [Figure 3] Schematic perspective view showing the sliding member according to the present embodiment [Figure 4] Perspective sectional view showing the characteristics of the sliding member according to the present embodiment [Figure 5] Partial sectional view of the sliding member and the holding member according to the present embodiment [Figure 6] Perspective sectional view showing the characteristics of the sliding member according to the second embodiment [Figure 7] Partial sectional view of the sliding member according to the second embodiment [Figure 8] Partial top view showing an example of the concave shape according to the second embodiment [Figure 9] Partial top view and partial sectional view showing another example of the concave shape according to the second embodiment [Figure 10] Partial top view and partial sectional view showing another example of the concave shape according to the second embodiment [Figure 11] Partial top view and partial sectional view showing another example of the concave shape according to the second embodiment [Figure 12] Schematic sectional view showing the pressing method of the sliding member

Mode for Carrying Out the Invention

[0015] The fixing device which is an embodiment of the present invention will be described with reference to the drawings. Note that the embodiments and examples shown below are illustrative, and for example, those skilled in the art can appropriately modify and implement the detailed configurations without departing from the spirit of the present invention.

[0016] In the drawings referred to in the following description, unless otherwise specified, elements denoted by the same reference numerals have the same functions.

[0017] The present embodiment will be described. An image forming apparatus suitable for using the fixing device according to the present embodiment will be described with reference to FIG. 1. The image forming apparatus 100 shown in Figure 1 is a tandem-type intermediate transfer full-color printer in which yellow, magenta, cyan, and black image forming units Pa, Pb, Pc, and Pd are arranged along an intermediate transfer belt 20.

[0018] First, the material transport process of this image forming apparatus 100 will be described. The recording material P is stored in a stacked form within the paper feed cassette 10 and is fed out from the paper feed cassette 10 by the paper feed roller 13 in accordance with the image formation timing.

[0019] The recording material P, fed out by the paper feed roller 13, is transported to the registration roller 12 located in the middle of the transport path 114. Then, after the registration roller 12 corrects the skewness and timing of the recording material P, the recording material P is sent to the secondary transfer section T2.

[0020] The secondary transfer section T2 is a transfer nip section formed by the secondary transfer inner roller 21 and the secondary transfer outer roller 11, and transfers a toner image onto the recording material in response to the application of a secondary transfer voltage to the secondary transfer outer roller 11.

[0021] Next, we will explain the image formation process, which is delivered to the secondary transfer section T2 at a similar timing to the transport process of the recording material P to the secondary transfer section T2 described above.

[0022] First, let me explain the image forming section. The image forming sections Pa, Pb, Pc, and Pd for each color are configured almost identically, except that the toner colors used in the developing units 1a, 1b, 1c, and 1d are yellow, magenta, cyan, and black.

[0023] Therefore, in the following, we will explain the black image forming unit Pd as a representative example, and omit explanations of the other image forming units Pa, Pb, and Pc.

[0024] The image forming unit Pd mainly consists of a developing device 1d, a charging device 2d, a photosensitive drum 3d, a photosensitive drum cleaner 4d, and an exposure device 5d, etc.

[0025] The surface of the photosensitive drum 3d, which rotates in the direction of arrow R1 in the figure, is uniformly pre-charged by the charging device 2d, and then an electrostatic latent image is formed by the exposure device 5d, which is driven based on the image information signal.

[0026] Next, the electrostatic latent image formed on the photosensitive drum 3d is developed into a toner image using a developer by the developing device 1d.

[0027] Then, when a primary transfer voltage is applied to the primary transfer roller 6d, which is positioned between the image forming unit Pd and the intermediate transfer belt 20, the toner image formed on the photosensitive drum 3d is primary transferred onto the intermediate transfer belt 20.

[0028] The small amount of primary transfer toner remaining on the photosensitive drum 3D is collected by the photosensitive drum cleaner 4D and prepared again for the next imaging process. The intermediate transfer belt 20 is tensioned by the secondary transfer internal roller 21, tension roller 22, and tension roller 23, and is driven in the direction of arrow R2 in the figure.

[0029] In this embodiment, the secondary transfer roller 21 also serves as a drive roller for driving the intermediate transfer belt 20. The image formation process for each color, which is processed in parallel by the image forming units Pa to Pd, is performed at the timing when the images are sequentially superimposed onto the toner images of the upstream colors that have been primary transferred onto the intermediate transfer belt 20.

[0030] As a result, a full-color toner image is ultimately formed on the intermediate transfer belt 20 and transported to the secondary transfer section T2. Furthermore, any remaining toner after passing through the secondary transfer section T2 is recovered by the transfer cleaner device 30.

[0031] Based on the transport and imaging processes described above, the timing of the recording material P and the full-color toner image are synchronized in the secondary transfer section T2, and secondary transfer is performed.

[0032] Subsequently, the recording material P is transported to the fixing device 50, where a predetermined amount of pressure and heat is applied to fix the toner image onto the recording material. The recording material P, on which the toner image has been fixed, is then discharged directly onto the output tray 120 by the output roller 14 when a single-sided image is not required.

[0033] In the case of double-sided image formation, the transport path is switched by a switching member 110 (sometimes called a flapper) from the path leading to the paper output tray 120 to the double-sided transport path 111, and the recording material P transported by the discharge roller 14 is transported to the double-sided transport path 111.

[0034] Subsequently, the leading and trailing ends are swapped by the reversing roller 112, and the material is sent again to the transport path 114 via the double-sided path 113. The subsequent transport and imaging process on the reverse side are the same as described above, so we will omit further explanation.

[0035] <Fusing device> Next, the fixing device 50 of this embodiment will be described with reference to Figure 2. As shown in Figure 2, the fixing device 50 of this embodiment can be broadly divided into a belt unit 300 and a pressure roller 330.

[0036] The pressure roller 330, acting as a rotating body, has its rotation axis supported by the frame 380 of the fixing device 50, and although not shown in the illustration, it is rotated via gears by a drive source. The pressure roller 330, acting as a contact member, contacts the outer circumferential surface of the fixing belt 310 of the belt unit 300, thereby applying pressure to the fixing belt 310.

[0037] The pressure roller 330 is movable between a pressure position, where it contacts and applies pressure to the fixing belt 310, and a non-pressure position, where it is separated from the fixing belt 310 and does not apply pressure. To enable the pressure roller 330 to move between a pressurized position and a non-pressurized position, the pressure roller 330 is supported by a pressurized lever 383 which is oscillated by a pressurized motor (not shown).

[0038] The pressure roller 330 may be, for example, one having an elastic layer of silicone rubber, fluororubber, or fluororesin on the outer circumference of a metal rotating shaft (core), or one having a release layer made of fluororesin such as PTFE, PFA, or FEP on the outer circumference of the elastic layer. In this embodiment, a pressure roller 330 was used, which had an elastic layer made of silicone rubber with a thickness of "3 mm" and a release layer made of PFA with a thickness of "30 μm".

[0039] <Belt Unit> As shown in Figure 2, the belt unit 300 mainly consists of an endless (cylindrical) and flexible, rotatable fixing belt 310, a heating roller 340, a steering roller 350, and a pressure pad member 400 (hereinafter referred to as pad 400).

[0040] In this embodiment, the fixing belt 310 is stretched by a heating roller 340, a steering roller 350, and a pad member 400. As the fixing belt 103, a resin belt made of resin, for example, which has an elastic layer with high thermal conductivity and low heat capacity, or a composite layer structure belt with a metal belt such as stainless steel (SUS) as the base layer and an elastic layer, a release layer, etc. on its outer circumference may be used.

[0041] In this embodiment, a fixing belt 103 was used, which had a base layer made of SUS, an elastic layer with a thickness of approximately 250 μm made of silicone rubber with a thermal conductivity of approximately 1.0 W / m·K, and a release layer with a thickness of 30 μm made of PFA tubing.

[0042] Furthermore, the release layer is preferably a sheet or coating layer with high release properties, and for example, fluororesins such as PFA or PTFE can be used. Alternatively, a highly heat-resistant sheet-like material, such as polyester, polyethylene terephthalate, or polyimidoamide, may be used as the base layer, with a conductive layer laminated on top of it, and a surface release layer further on top of that. In this specification, the term "fixing belt 310" includes thin, film-like belts.

[0043] The heating roller 340 is, for example, a stainless steel pipe with a thickness of 1 mm, and a halogen heater (not shown) is installed inside it. The heating roller 340, although not shown in the illustration, is rotated by a drive source via a gear. The fixing belt 310 rotates in accordance with the rotation of the heating roller 340.

[0044] Furthermore, as the heating roller 340 is heated by the halogen heater, the temperature of the fixing belt 310 rises via the heating roller 340. The fixing belt 310 is adjusted to a predetermined target temperature, for example, depending on the type of recording material P used for image formation, based on the detection result of a temperature sensor (not shown), such as a thermistor sensor.

[0045] The steering roller 350 presses the anchoring belt 310 from the inside outwards in order to tension the anchoring belt 310 to a predetermined tension. To that end, the steering roller 350 is biased by the spring 351. Thus, the steering roller 350 has the function of applying a predetermined tension to the anchoring belt 310.

[0046] Furthermore, the steering roller 350 controls the meandering of the anchor belt 310 in the direction of the rotation axis by turning a steering angle with its center or one end in the direction of its rotation axis (width direction) as the pivot point. In other words, the steering roller 350 also has the function of controlling the angle of the anchor belt 310.

[0047] The pad member 400 is positioned on the inner circumference side of the fixing belt 310, facing the pressure roller 330 with the fixing belt 310 in between. The pad member 400 has a stay 360, a holding member 320, and a sliding member 410. In particular, the holding member 320 and the sliding member 410 are sometimes collectively referred to as the pad member.

[0048] The stay 360 is a rigid metal member, such as stainless steel, that extends in the width direction along the fixing belt 310, and supports the holding member 320 so that it can be attached on the pressure roller 330 side.

[0049] The retaining member 320 supports the sliding member 410 so that it can be attached to the pressure roller 330 side. The retaining member 320 is a resin member formed to extend in a width direction intersecting the rotational direction of the fixing belt 310 along the stay 360. Such a retaining member 320 is formed from a material with good insulating and heat-resistant properties, such as phenolic resin, polyimide resin, polyamide resin, polyamide-imide resin, PEEK resin, PES resin, PPS resin, PFA resin, PTFE resin, or LCP resin.

[0050] The sliding member 410 slides against the inner circumferential surface of the anchoring belt 310. The sliding member 410 is fixed to the stay 360 with screws or the like via the retaining member 320. The sliding member 410 may be integrated with the retaining member 320. Alternatively, the sliding member 410 may be partially fixed to the stay 360 or the retaining member 320. For example, the sliding member 410 may be fixed to the retaining member 320 with screws or the like using the screw holes 420 at both ends in the width direction of the sliding member 410.

[0051] In this embodiment, a sliding member 410 attached to a retaining member 320 supported by a stay 360 contacts the inner circumferential surface of the fixing belt 310, pressing the fixing belt 310 from the inner circumferential surface side toward the fixing nip portion N.

[0052] This ensures that the fixing nip section N, which holds, transports, pressurizes, and heats the recording material P on which the toner image has been formed, is formed more reliably.

[0053] Furthermore, by supporting the sliding member 410 and the holding member 320 on the rigid stay 360, the deflection generated in the sliding member 410 by the pressure from the pressure roller 330 is reduced, thereby ensuring a uniform nip width in the direction of the rotation axis of the pressure roller 330.

[0054] Furthermore, it is preferable to interpose a lubricant, such as silicone oil, between the sliding member 410 and the fixing belt 310 so that the fixing belt 310 and the sliding member 410 can slide smoothly against each other.

[0055] <Sliding member> Next, the sliding member 410, which is a feature of the present invention, will be described with reference to Figures 3 and 4. Please note that these drawings are schematic representations for the sake of explanation and may not accurately depict the actual shape, size, or arrangement of the objects.

[0056] Figure 3 is a schematic perspective view of the sliding member 410. The region of the sliding member 410 held by the retaining member 320 is indicated by α. Region α is the area from dashed line x to dashed line y in Figure 3, excluding the parts that form the screw fastening holes 420 formed at both ends in the width direction of the sliding member 410. Dashed lines x and y indicate the ends in the width direction where the sliding member 410 is held by the retaining member 320.

[0057] As shown in Figure 3, multiple convex-shaped protrusions 411 are formed on the sliding surface of the sliding member 410. These protrusions 411 are sometimes referred to as embossing.

[0058] This protrusion 411 is a sliding surface with the fixing belt, and is designed to retain lubricant and reduce the contact area so that the coefficient of friction with the inner surface of the fixing belt does not exceed a predetermined value. The protrusion 411 can be any shape as long as it reduces the contact area and can hold the lubricant, and there are no restrictions on the shape of the protrusion 411, such as cylinder, prism, or hemisphere. There are also no restrictions on the presence or absence of corner radii or tapers.

[0059] Among these, the frustoconical shape shown in Figure 3 is preferable, with a tip diameter of Φ0.15mm to Φ0.45mm, a height (a) of 0.15mm to 0.3mm, and a taper angle of 5° to 50° being particularly effective.

[0060] It is desirable for the taper angle to be constant, and it should be avoided if it widens towards the base, as this increases the cross-sectional area and improves the efficiency of heat conduction. The thickness (c) of the sliding member is 0.4 mm to 1.4 mm.

[0061] The arrangement of the protrusions 411 can be any arrangement, but if they are too densely packed, the contact area increases and the coefficient of friction increases, and if they are too scattered, there is a risk of deflection in the fixing belt. Therefore, the arrangement pitch of the protrusions is preferably 0.5 mm to 3.0 mm, assuming that the shapes do not interfere with each other. In addition, the distance (spacing) between the centers of adjacent protrusions 411 in the conveying direction is 1.0 mm or more. Furthermore, the area S of the tip surface of the protrusion 411 (embossed tip shape area) is 0.031 mm². 2 It is preferable to do so.

[0062] Figure 4 is a perspective cross-sectional view showing the features of the sliding member 410. As shown in Figure 4, a recessed portion 412 is formed on the back surface of the protrusion 411 of the sliding member 410 in the same phase as the protrusion 411.

[0063] The recess 412 is formed in a position that overlaps with the recording material transport direction in a direction perpendicular to the recording material transport direction in order to minimize changes in wall thickness, and it is preferable that it has a shape similar to the convex portion 411. Furthermore, the depth (b) of the recess 412 is preferably 0.15 mm to 0.3 mm, and in particular, the projected shape when viewed from the vertical direction is circular, with a diameter of Φ0.15 mm to Φ0.45 mm being preferred. This is because a circular shape does not have stress concentration points.

[0064] Furthermore, it is effective to form the dimensions within a range that is considered suitable for the protrusion 411. The position of the recess 412 is such that the outer edge of the recess 412 is within a range in the central direction from the base edge of the taper of the convex portion 411. Furthermore, it is preferable that the distance from the base edge of the taper to the bottom edge of the recess 412 be 80% to 30% of the plate thickness. This is because insulation is hardly achieved for more than 80% of the plate thickness, and rigidity decreases for less than 30% of the plate thickness, which may cause the embossed area to break.

[0065] In this embodiment, the number of protrusions 411 and the number of recesses 412 in region α are the same. However, in order to improve heat insulation, the number of recesses 412 may be increased to create more air layers than the number of protrusions 411. In other words, the number of recesses on the surface in contact with the holding member may be greater than or equal to the number of protrusions on the surface sliding against the inner circumferential surface of the belt. The positions where the recesses 412 are formed are such that they overlap with the protrusions 411 in a direction perpendicular to the conveying direction, acting as an air layer to suppress the transfer of heat from the protrusions 411 in contact with the belt, which conduct the most heat, to the holding member 320. If the number of recesses 412 is increased to more than the number of protrusions 411, further recesses 412 may be formed between one recess 412 and another recess 412.

[0066] The sliding member 410 is mainly made of a metal material that has good strength, rigidity, sliding properties, and heat resistance. By using materials such as iron, aluminum, aluminum alloys, copper, and copper alloys, the desired load-bearing capacity can be ensured. Examples of iron include stainless steel (SUS304, SUS316, etc.), mild steel (SPCC, SPCE, etc.), and general structural carbon steel (SS400, etc.). Furthermore, these may be pre-plated with zinc, nickel, copper, or other materials, or they may be coated with a lubricating paint containing fluororesin and graphite.

[0067] Examples of aluminum include A1100 and A1050, while examples of aluminum alloys include A2017 and A5052 (including anodized products). Examples of copper include C1100, while examples of copper alloys include C2700 and C2801.

[0068] A method for manufacturing the sliding member 410 will be described. The sliding member 410 can be manufactured by any method, but for example, it can be manufactured by press molding. An upper and lower mold having inverted shapes of the convex portion 411 and the concave portion 412 are manufactured, and a sheet material is pressed to obtain a molded product.

[0069] Alternatively, roll forming may be used. The convex and concave shapes are machined onto the rolls, and the sheet material is sandwiched between the rolls and rotated while being pressed against them to machine the convex and concave shapes, respectively.

[0070] Alternatively, the sliding member 410 may be manufactured using a removal process. Removal processes can utilize processing techniques such as cutting, blasting, and laser processing, either individually or in combination. Specifically, machining equipment such as machining centers, lathes, and milling machines, as well as electrical discharge machining (EDM) equipment that can process materials under low load, can be used.

[0071] In addition, the product can be manufactured using etching or 3D printing, and it is also possible to manufacture it by combining the above-mentioned processing methods.

[0072] Figure 5 is a partial cross-sectional view of the sliding member 410 and the holding member 320, which illustrate the features of the present invention. As shown in Figure 5, the sliding member 410 of the present invention has a recess 412. Let A be the area of ​​the support surface that contacts the holding member 320 in region α of the sliding member 410, and B be the area of ​​region α of the sliding member 410 that does not contact the holding member 320. In this case, it is preferable that the area ratio of area A to the total area of ​​region α ((A / (A+B)) × 100%) be 15% or more and 60% or less. By using the configuration of this embodiment, the contact area with the holding member 320 can be reduced.

[0073] The recess 412 is an air layer, and its thermal conductivity is 0.01 to 0.04 [W / mK], which is 1 / 10 to 1 / 100 of that of resin or metal. Since the amount of heat transferred between multiple components is generally proportional to the thermal conductivity and contact area, the thermal insulation of the sliding member 410 is improved.

[0074] According to the present invention, without using an insulating material, thermal insulation can be ensured by reducing the contact area between the sliding member and another member that comes into contact with the sliding member, thereby improving the thermal insulation of the sliding member.

[0075] Next, a second embodiment of the present invention is shown. Figure 6 is a perspective cross-sectional view showing a sliding member 510 according to a second embodiment of the present invention.

[0076] Figure 7 is a partial cross-sectional view of the area around the second recess 413, showing the concave shape of the sliding member 510 in the second embodiment of the present invention. Unlike the sliding member 410, the sliding member 510 has a second recess 413 formed around the protrusion 411. The sliding member 510 has a protrusion 411 that protrudes toward the inner circumferential surface of the fixing belt 310 relative to the dashed line z which serves as the reference plane, and a second recess 413 that is recessed toward the holding member 320 relative to the dashed line z. Furthermore, in a cross-sectional view (Figure 7) of the sliding member 510 cut in a cross section perpendicular to the direction of transport of the recording material, the second recess 413 is positioned adjacent to the protrusion 411.

[0077] The second recess 413 reduces the area of ​​the cross-sectional area Y in the thickness direction of the sliding member 510 around the protrusion 411, suppressing heat transfer from the fixing belt through the protrusion 411 and improving the thermal insulation performance of the sliding member 510. Furthermore, when the sliding member is viewed from a direction perpendicular to the conveying direction, the contour of the recess is contained within the central part of the contour of the convex portion. In other words, the circular shape of the recess 412 is sized to fit within the circular shape of the convex portion 411. Also, the diameter of the convex portion 411 increases as it approaches the dashed line z. The diameter of the recess 412 is configured to be smaller than the smallest diameter of the convex portion 411.

[0078] The recess 413 in the second embodiment may have any shape as long as the cross-sectional area Y is reduced. Preferably, the second recess 413 has a width of 0.1 to 1.0 mm from the intersection of the protrusion 411 and the dashed line z, and a depth (d) of 5 μm to 50 μm. Furthermore, the distance from the base edge of the protrusion to the bottom edge of the recess is 30% to 80% of the thickness of the sliding member excluding the protrusion.

[0079] Figures 8 to 11 are partial top views and partial cross-sectional views showing another pattern of the second recess 413 in the second embodiment of the present invention. As shown in Figures 8 to 11, the second recessed portion 413, which has a concave shape, does not necessarily need to be formed all around the convex portion 411, but may be provided intermittently.

[0080] For example, the components can be arranged intermittently in an arc shape around the convex portion 411 as shown in Figure 8, or intermittently in the circumferential direction as shown in Figure 9. Of course, shapes that combine Figures 8 and 9, or shapes other than circles, are also acceptable, and it is fine to add radii to the corners or tapered walls.

[0081] Furthermore, as shown in Figures 10 and 11, the bottom surface of the concave shape does not necessarily have to be flat; shapes such as V-shaped grooves or U-shaped grooves may be used, or multiple concave shapes with acute angles on the bottom surface, resembling a pincushion, may be provided.

[0082] The wider the second concave opening area, the smaller the cross-sectional area Y becomes, improving thermal insulation, but there is a concern that this may lead to a decrease in rigidity. Therefore, it is effective to form the concave shape around the convex portion 411 with a size that prevents interference between the concave shapes, and to set the depth to 50% or less of the plate thickness of the sliding member.

[0083] Furthermore, it is not always necessary to provide a concave shape around every protrusion 411; it is possible to limit the locations where concave shapes are provided, taking into consideration rigidity and other factors. The recessed area 413 can be filled in with lubricating paint or other materials applied in the next step if necessary, without causing any problems.

[0084] This is because most of the heat transfer occurs within sliding members that are made of metal material and have a large plate thickness, rather than in the lubricated painted area. The manufacturing method is the same as for the sliding member 410, and it can be processed using general press working or removal processes.

[0085] According to this embodiment, the plate thickness around the protrusion 411 is reduced, making it possible to further improve the heat insulation performance of the sliding member.

[0086] <Manufacturing method> Next, the manufacturing method of the sliding member 410 will be explained in more detail. The sliding member 410 is most effectively manufactured by press molding.

[0087] Figures 12(a) to 12(e) illustrate schematic cross-sectional views illustrating a method for manufacturing the sliding member 410 by press forming. First, prepare the plate material 600 to be processed, the lower die 611, and the upper die 612, as shown in Figure 12(a).

[0088] The lower mold 611 has a hole shape 621 which is the inverse of the convex portion 411, and is made of a material with higher hardness than the metal plate 600. For example, if the plate material 600 is stainless steel, it could be high-speed tool steel (SKH61, powder high-speed steel) or cemented carbide.

[0089] Although not shown here, if a second recess 413 is provided around the convex portion 411, it is also possible to place a shape that is an inversion of the second recess 413 on the lower mold 611. The upper die 612 also has a punch 622 which has the shape of the recess 412 inverted.

[0090] It is preferable that the punch 622 be manufactured separately from the upper die 612. Punch 622 is a part that is subjected to load during pressing, and if it breaks, only the punch 622 needs to be replaced.

[0091] Furthermore, it becomes unnecessary to manufacture the entire upper mold from a high-hardness material; for example, only the punch 622 can be made of cemented carbide, while the rest can be made from a lower-hardness material. It is preferable that the hole shape 621 and the punch 622 have the same center position.

[0092] Even in the worst-case scenario, the edge of the punch 622 tip will be positioned inward from the edge of the outer shape of the hole 621. If the punch 622 is on the outside, the pressing force applied to it will vary within the pressing surface, potentially causing uneven deformation and damage to the punch 622. It is also effective to provide a plate holder 623 on the upper mold 612.

[0093] The plate holder 623 applies downward pressure with a spring (not shown), preventing deformation or displacement of the workpiece and serving to release the workpiece that has become stuck in the punch.

[0094] Figure 12(b) shows an intermediate stage of the press working process. The lower die 611 and the upper die 612 clamp the plate material 600 vertically, and in the process, the plate holder 623 first contacts the plate material 600 to fix its position. Then, as shown in Figure 12(c), press processing is performed using the punch 622.

[0095] In this case, the deformation of the plate material 600 can be suppressed by the plate holder 622. In press forming, the mold shape is transferred with relatively high precision, so unlike etching and other processes, excess material around the convex shape can be minimized.

[0096] Figure 12(d) shows the state after the initial press working has been completed. The presence of the board holder 623 allows the punch 622 to be smoothly removed from the board material 600 after successful punching. Figure 12(e) shows the workpiece moved in the planar direction for the next press operation. For press forming of sliding members, it is effective to move the sheet material to different positions after pressing and shape it multiple times, dividing it to form the required number of convex and concave shapes. By doing so, it is possible to reduce the processing time for the hole shape 621 and the number of parts in the punch section 622, which affect the processing cost of the mold.

[0097] By performing the press work as described above, the metal plate 600 has a convex portion 411 and a concave portion 412 on its back surface, thus forming an important part for use as a sliding member.

[0098] Subsequently, the sliding member 410 is manufactured by correcting the warp deformation caused by press working, and by processing such as creating screw holes and positioning shapes for attachment to the retaining member, and surface treatment as necessary. [Explanation of Symbols]

[0099] 50 Fixing device 310 Fixing belt 320 Retaining member 330 Rotating body (pressure roller) 360 Stay 410 Sliding member 411 Convex part 412 Concave shape 413 Second concave shape 510 Second sliding member 600 metal plate 611 Lower mold 612 Upper mold 621 Hole shape 622 Punch 623 Board holder N Fixing nip section P recording material

Claims

1. A fixing device that fixes a toner image supported on the recording material at the nip section onto the recording material, An endless, rotatable belt for heating recording material, A contact member that contacts the outer surface of the belt, A pad member is positioned on the inner circumferential surface of the belt, facing the contact member with the belt in between, and forming the nip portion between the belt and the contact member. The pad member consists of a sliding member that slides against the inner circumferential surface of the belt and a holding member that holds the sliding member. The sliding member has a plurality of protrusions on the surface that slides against the inner circumferential surface of the belt, and a plurality of recesses on the surface that contacts the holding member. A fixing device characterized by the following features.

2. The recess and the protrusion are located in a position that overlaps in a direction perpendicular to the transport direction of the recording material. The fixing device according to feature 1.

3. The area in contact between the sliding member and the holding member is 15% to 60% of the area of ​​the sliding member. The fixing device according to feature 1.

4. The sliding member is made of metal. The fixing device according to feature 1.

5. The recess is circular when viewed in a direction perpendicular to the direction of transport of the recording material. The fixing device according to feature 1.

6. The aforementioned protrusion is circular when viewed in a direction perpendicular to the direction of transport of the recording material. The fixing device according to feature 1.

7. The number of recesses on the surface that contacts the retaining member is equal to or greater than the number of protrusions on the surface that slides against the inner circumferential surface of the belt. The fixing device according to feature 1.

8. The number of protrusions on the surface that slides against the inner circumferential surface of the belt is the same as the number of recesses on the surface that contacts the retaining member. The fixing device according to feature 1.

9. The sliding member has a convex portion that protrudes toward the inner circumferential surface of the belt from a predetermined reference surface and a second recess that is recessed toward the holding member from the predetermined reference surface, the second recess being positioned adjacent to the convex portion. The fixing device according to feature 1.

10. A second recess is formed around the aforementioned protrusion. The fixing device according to feature 9.

11. Second recesses are intermittently formed around the aforementioned recess. The fixing device according to feature 9.

12. When the sliding member is viewed from a direction perpendicular to the conveying direction, the contour of the recess is contained within the central part of the contour of the convex portion. The fixing device according to feature 1.

13. The distance from the base edge of the protrusion to the bottom edge of the hole in the recess is 30% to 80% of the thickness of the sliding member excluding the protrusion. The fixing device according to feature 1.

14. Prepare the planks, A first mold having multiple concave shapes formed In a method of pressing a sheet metal by sandwiching it between two dies, each having a punch positioned such that the contour of the portion in contact with the sheet metal is inward from the contour of the concave shape in the vertical direction of the sheet metal, Pressing and moving the plate material in the planar direction multiple times is performed to repeatedly form convex and concave portions on the plate material. A method for manufacturing a sliding member, including the following.

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