Image forming apparatus and method for manufacturing frame of image forming apparatus

Abstract

To set up a frame of an image forming apparatus by using an adhesive, and to reduce the weight of the frame while ensuring the rigidity of the frame in an adhesive peeling direction.SOLUTION: An image forming apparatus has an image forming unit that forms an image on a recording material, a first sheet metal and a second sheet metal that are provided to face each other and sandwich the image forming unit, and a third sheet metal that is provided between the first sheet metal and the second sheet metal and joined to the first sheet metal and the second sheet metal. The first sheet metal and the third sheet metal are joined to each other at at least two welding positions, and within a range sandwiched by the two welding positions in an area where the first sheet metal and the third sheet metal are in contact with each other, an adhesive is applied between the first sheet metal and the third sheet metal and the first sheet metal and the third sheet metal are joined to each other.SELECTED DRAWING: Figure 11

Description

Technical Field

[0001] The present invention relates to a frame of an image forming apparatus.

Background Art

[0002] An image forming apparatus using an electrophotographic method has a frame (also referred to as a frame body) that supports an image forming unit that forms an image on a recording material, a conveyance unit that conveys a sheet, and the like. It is widely known that the frame is configured by fastening a plurality of sheet metals with screws. Here, if the rigidity of the frame is low, it leads to image defects such as distortion and color misregistration of the image formed on the sheet. For this reason, in order to achieve the frame rigidity required for the image forming apparatus, measures are taken to improve the frame rigidity by increasing the fastening points of the sheet metals with screws or increasing the thickness of the sheet metals.

[0003] On the other hand, for example, in Patent Document 1, it is described that a plurality of sheet metals are joined by using an adhesive to assemble the frame of the image forming apparatus. In Patent Document 2, it is described that the frame of the image forming apparatus is assembled by combining two methods of fastening with screws and using an adhesive. Thus, by assembling the frame using an adhesive, the frame can be lightened by the amount of screws not used.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, there are challenges when joining multiple sheet metals with adhesive. Generally, adhesives are not strong against forces in the direction of delamination, so when joining multiple sheet metals with adhesive, it is necessary to compensate for the rigidity of the frame in the direction of delamination by methods such as screw fastening. Patent Document 2 describes a configuration in which the sheet metals are fastened together with screws near the location where the adhesive is applied to prevent the adhesive from peeling off. In the configuration of Patent Document 2, the number of screws could be reduced compared to conventional methods by using adhesive, but in recent years there has been a demand for further weight reduction of the frame.

[0006] In view of the above-mentioned problems, the present invention aims to reduce the weight of the frame while ensuring frame rigidity in the direction of adhesive peeling, in a configuration in which the frame of an image forming apparatus is assembled using an adhesive. [Means for solving the problem]

[0007] The present invention for achieving the above objective is an image forming apparatus comprising: an image forming unit for forming an image on a recording material; a first sheet metal and a second sheet metal provided opposite to the image forming unit so as to sandwich the image forming unit; and a third sheet metal provided between the first sheet metal and the second sheet metal and joined to the first sheet metal and the second sheet metal, wherein the first sheet metal and the third sheet metal are welded at at least two welding positions, and in the area where the first sheet metal and the third sheet metal are in contact, an adhesive is applied between the first sheet metal and the third sheet metal in the area sandwiched by the two welding positions, thereby joining the first sheet metal and the third sheet metal. [Effects of the Invention]

[0008] According to the present invention, in a configuration in which the frame of an image forming apparatus is assembled using an adhesive, it is possible to reduce the weight of the frame while ensuring the frame's rigidity in the direction of adhesive peeling. [Brief explanation of the drawing]

[0009] [Figure 1]Cross-sectional view showing the overall configuration of the image forming apparatus. [Figure 2] Three-dimensional view of the frame of an image forming apparatus. [Figure 3] Flowchart of the assembly process for the frame of an image forming apparatus [Figure 4] Diagram illustrating the adhesive application process. [Figure 5] Diagram illustrating the frame assembly process. [Figure 6] A three-dimensional diagram showing the tip of the welding machine arm. [Figure 7] Diagram illustrating the frame welding process. [Figure 8] Diagram showing the position of the arm tip when welding the front plate and main stay. [Figure 9] Cross-sectional view showing the welding process between the front plate and the main stay. [Figure 10] A diagram explaining why the center of the frame cannot be welded. [Figure 11] Diagram showing the welding positions and adhesive application positions for the front plate and main stay / base plate stay. [Figure 12] Diagram showing the welding positions and adhesive application positions for the rear side plate and main stay. [Figure 13] This diagram illustrates what happens when a peeling force is applied to the front plate and the end of the main stay. [Figure 14] This diagram illustrates what happens when a peeling force is applied to the center of the front plate and main stay. [Figure 15] Cross-sectional diagram illustrating the effect when a peeling force is applied to the front side plate and main stay. [Figure 16] Diagram illustrating the adhesive application process in a modified example. [Figure 17] Diagram showing the welding positions and adhesive application positions of the front plate and main stay / base plate stay in a modified example. [Modes for carrying out the invention]

[0010] [Example 1] (Overall configuration of the image forming apparatus) FIG. 1 is a cross-sectional view showing the overall configuration of the image forming apparatus 100 of the present embodiment. The image forming apparatus 100 of the present embodiment is a laser beam printer that can print a color image on a sheet S.

[0011] In the following description, when the image forming apparatus 100 is installed on a horizontal plane, the height direction (vertical direction) of the image forming apparatus 100 is defined as the Z direction. A direction that intersects the Z direction and is parallel to the axial direction (main scanning direction) of the photosensitive member 7, which will be described later, is defined as the Y direction. A direction that intersects the Y direction and the Z direction is defined as the X direction. The X direction, Y direction, and Z direction preferably intersect perpendicularly to each other. For the sake of convenience, the plus side in the X direction is referred to as the right side, the minus side as the left side, the plus side in the Y direction as the front side or the front face side, the minus side as the rear side or the back face side, and the plus side in the Z direction as the upper side, the minus side as the lower side.

[0012] 1 is the apparatus main body of the image forming apparatus, 2 is a cassette that stores the sheet S and is detachable from the apparatus main body 1, and 3 is a paper feeding unit. The sheet S accommodated in the cassette 2 is sent out onto the conveyance path one by one by the paper feeding unit 3, and is sent to the registration roller 5 via the intermediate conveyance roller 10. The registration roller 5 corrects the skew of the sheet S. 4 is a manual paper feeding unit.

[0013] The image forming apparatus 100 has four image forming units 6Y, 6M, 6C, 6K corresponding to yellow, magenta, cyan, and black. Hereinafter, for the sake of brevity, the alphabet is omitted and it is denoted as the image forming unit 6. The same applies to other members. The image forming unit 6 has photosensitive members 7Y, 7M, 7C, 7K (photosensitive member 7) and charging units 8Y, 8M, 8C, 8K (charging unit 8) that charge the surface of the photosensitive member 7. Further, it has developing units 9Y, 9M, 9C, 9K (developing unit 9) that develop the electrostatic latent image formed on the photosensitive member using toner. These, such as the photosensitive member 7 and the developing unit 9, are held in one container and constitute a cartridge that is integrally detachable from the apparatus main body 1.

[0014] 12 is an optical scanning unit (scanner unit) that scans the photoreceptor 7 with light corresponding to the image information. The optical scanning unit 12 is located below the photoreceptor 7 in the vertical direction (Z direction). In this embodiment, the optical scanning unit 12 is a laser scanner unit that scans the photoreceptor 7 by deflecting laser light emitted from a semiconductor laser with a rotating polyhedron mirror.

[0015] An intermediate transfer unit 15 is provided at the top of the developing unit 9. The intermediate transfer belt 17, onto which the toner image formed on the photoreceptor 7 is transferred, is a rotatable, endless belt stretched over a plurality of tension rollers. Primary transfer rollers 18Y, 18M, 18C, and 18K (primary transfer rollers 18) are in contact with the inner surface of the intermediate transfer belt 17. The primary transfer rollers 18 form a primary transfer section with each photoreceptor 7 via the intermediate transfer belt 17. In each primary transfer section, the toner image is transferred from each photoreceptor 7 to the intermediate transfer belt 17 by applying a voltage to the primary transfer roller 18. The intermediate transfer belt 17, the plurality of tension rollers that stretch the intermediate transfer belt 17, and the plurality of primary transfer rollers 18 are unitized as an intermediate transfer unit 15 and are configured to be detachable from the main body 1 of the device.

[0016] The secondary transfer roller 20 is in contact with the intermediate transfer belt 17, and forms a secondary transfer section 16 with the opposing roller via the intermediate transfer belt 17. In the secondary transfer section 16, the toner image transferred onto the intermediate transfer belt 17 is transferred to the sheet S. Toner remaining on the intermediate transfer belt 17 during the secondary transfer process is removed by the cleaning unit 21. The toner removed by the cleaning unit 21 is transported to the toner collection container 22 by a waste toner transport means (not shown). A high-voltage power supply board 13 for generating voltages to be applied to the charging unit 8, developing unit 9, primary transfer roller 18, secondary transfer roller 20, etc. is located above the intermediate transfer unit 15 and below the toner collection container 22.

[0017] The sheet S onto which the toner image has been transferred in the secondary transfer unit 16 is transported to the fuser unit 23. The fuser unit 23 has a heating unit 23a with a heat source and a pressure roller 23b that, together with the heating unit 23a, forms a fuser nip. The sheet S, which carries the unfixed toner image, is held and transported in the fuser nip and then heated and fixed to the sheet S.

[0018] The output tray 25 is located above the intermediate transfer belt 17 and supports the sheets S that are ejected from inside the main body 1 of the device. The sheets S onto which the toner image has been transferred in the secondary transfer unit 16 are transported via the fuser unit 23 to the output roller pair 24, and then ejected into the output tray 25 by the output roller pair 24.

[0019] (Frame of an image forming apparatus) Next, the frame 200 (also called the frame body) of the image forming apparatus 100 will be explained in detail using Figure 2.

[0020] The frame 200 comprises a front side plate 27 (first sheet metal) and a rear side plate 28 (second sheet metal) arranged in parallel, and a plurality of stays (third sheet metal) suspended between the side side plates. Both the side side plates and each stay are made of sheet metal.

[0021] The front plate 27 is provided with a large hole 27a that allows the cartridge (image forming unit 6) to be inserted and removed from the front of the device. The cartridge is guided into the device by a cartridge rail (not shown) provided on the main stay 29 and pushed upward (from the negative Z-direction to the positive Z-direction) by a biasing member such as a spring provided on the cartridge rail. As a result, the positioning part (not shown) in the longitudinal direction of the cartridge comes into contact with the recess 27b of the front plate, which is enclosed by a dotted line in Figure 2, and the position of the cartridge is determined with high precision. The rear plate 28 is also provided with a similar recess 28b, and the positional accuracy of the cartridge can be improved by accurately determining the relative position of both side plates.

[0022] The feed stay 30 is fitted with a unit that holds the intermediate transport roller 10 and the registration roller 5 (both shown in Figure 1), and supports a portion of the transport path of the sheet S. The high-voltage power supply board 13 (shown in Figure 1) is fitted to the substrate stay 31. The high-voltage power supply board 13 is secured to the substrate stay 31 by metal screws, thereby ensuring grounding of the high-voltage power supply board 13.

[0023] The lower left stay 32 has an internal positioning section (not shown) for mounting the optical scanning unit 12 (shown in Figure 1). The optical scanning unit 12 is mounted so as to bridge a part of the feed stay 30 and the lower left stay 32. The lower fixing stay 33 is located below the fixing unit 23. The upper right stay 34 and lower right stay 35 are shaped to hold exterior parts (not shown) of the image forming apparatus 100. The right rear pillar 36 and the left front pillar 38 are connected to other members to reinforce the rigidity of the frame 200.

[0024] (Frame assembly process) Next, the assembly process (manufacturing method) of the frame 200 will be explained using the flowchart in Figure 3. The assembly process of the frame 200 described in Figure 3 is broadly divided into an application process in which adhesive is applied, and a welding process in which sheet metal with adhesive applied is combined and welded together.

[0025] Furthermore, the flowchart in Figure 3 is executed by workers responsible for assembly and automated robots that operate according to the program. Here, we will explain the process by which workers and automated robots work together to assemble the frame 200.

[0026] First, the application process for the adhesive will be explained. This is shown in Figure 3. First, the operator sets the front side plate 27 and the rear side plate 28 horizontally into the adhesive application device. Both side plates are set in the application device in the positions shown in Figures 4(a) and 4(b). The adhesive is a two-part acrylic adhesive, and is filled into two syringes 80 and 81, respectively, as shown in Figure 4(b). Syringes 80 and 81 are connected to arms 82 and 83 of the automatic application robot, respectively, and are held so as to be movable in the XYZ directions. The automatic application robot is programmed to move arms 82 and 83 to predetermined application locations and apply a predetermined amount of adhesive.

[0027] Furthermore, the front plate 27 and rear plate 28 are each provided with a cross-shaped mark (not shown) to serve as a guide for adhesive application. The cross-shaped mark is, for example, about 0.3 mm deep and a few millimeters in size, allowing workers or automated application robots equipped with cameras to confirm the adhesive application position. Also, since only a few millimeters in size is required, drilling shapes like those used when fastening with screws are not necessary for the sheet metal. Therefore, there are no space constraints on the adhesive application area, and the degree of freedom in shape is increased.

[0028] In this embodiment, as shown in Figures 4(a) and 4(b), adhesive is applied to a total of 23 locations: 13 locations (60a to 60q) on the surface of the front side plate 27 and 10 locations (60r to 60zz) on the surface of the rear side plate 28. The automatic application robot is programmed to complete the adhesive application process at each location in approximately several tens of seconds. By using the automatic application robot, the complexity of manual adhesive application and the worry of missed application areas are eliminated. Furthermore, since the application of adhesive to all locations is completed well before the applied adhesive hardens, it is possible to move on to the next step of assembling the frame 200 with ample time.

[0029] In this embodiment, the viscosity of the adhesive is relatively high, approximately 10,000 to 20,000 [mPa·s]. Therefore, even when the side panels are moved from a horizontal position for adhesive application to an upright position for assembling the frame 200, the adhesive does not immediately flow out from the side panels.

[0030] Next, the process of assembling the front side plate 27 and the rear side plate 28 will be described. Figure 5 shows the position of each sheet metal, including the side plates to which adhesive has been applied, just before they are assembled as the frame 200. Each sheet metal is fixed and held in place by magnets or the like on a frame tool (not shown) to maintain its position. Then, by moving the sheet metal holding part of the frame tool, each sheet metal is engaged in a predetermined order in the direction of the arrows in the figure, and the welding process begins with all the sheet metal assembled. The assembly order is as follows: First, the front side plate 27 and the rear side plate 28 are engaged in the direction of the arrow (Y direction). Next, the lower left stay 32 and the lower right stay 35 are engaged in the direction of the arrow (X direction), and the upper right stay 34 is engaged in the direction of the arrow (Z direction), and the frame 200 is assembled.

[0031] The welding process is carried out after the frame 200 is transported into the welding machine while its orientation is maintained by a framing tool. In this embodiment, there are approximately 50 welding points. All parts except the main stays 29 and base plate stays 31 are fastened by welding alone.

[0032] The welding operation is programmed to be performed continuously by an automated welding robot. Figure 6 shows the arm tip 70 of the automated welding robot in this embodiment. The arm tip 70 is equipped with two movable arm-shaped nozzles 71 and 72, and the sheet metal is clamped between the tips 73 of the two nozzles and welded.

[0033] Figure 7 shows the posture of the arm tip 70 of the automatic welding robot when welding the front plate 27 to the main stay 29, and the front plate 27 to the base plate stay 31. The arm tip 70 moves sequentially while welding at multiple locations, but Figure 7 simultaneously displays the welding posture of the arm tip 70 at four welding points.

[0034] Figure 8 shows one position for welding the front plate 27 and the main stay 29. It shows the moment when the tip of the arm 70 of the automatic welding robot welds the two sheets of metal at the welding position 50a. Figure 9 shows a T-T cross-section of the arm tip at this time. Figure 9 shows how the front plate 27 and the main stay 29 are sandwiched between the tips 73 of the nozzles 71 and 72. The tip 73 of the nozzle is capable of conducting electric current, and by passing current between nozzles 71 and 72, a portion of the sheet metal sandwiched by the tip 73 of the nozzle can be welded.

[0035] Furthermore, in Figure 9, the position of welding position 50a in the Z direction cannot be moved any further upward (towards the positive Z direction) than it is currently. This is because a predetermined amount of clearance must be maintained in the Z direction between the nozzle 72 of the automatic welding robot and the main stay 29.

[0036] Using an automated welding robot in this way allows two sheets of metal to be joined together with high joint strength without using screws. On the other hand, it is difficult to insert the automated welding robot into the central part 75 of the frame 200. In order to weld the central part 75 of the frame, it is necessary to insert the tip of the arm 70 through the gap 76 between the main stay 29 and the lower left stay 32, as shown in Figure 10(a), but this gap is too small to allow the tip of the arm 70 to enter. Alternatively, one could consider inserting the tip of the arm 70 through the gap 77 between the feed stay 30 and the lower right stay 35, as shown in Figure 10(b), but similarly the gap 77 is insufficient.

[0037] As the image forming apparatus 100 has been miniaturized, the frame 200 has also been miniaturized, making it difficult to widen the gaps 76 and 77 beyond their current size. Furthermore, there are limitations on reducing the size of the arm tip 70. Therefore, a fastening means other than welding is required at the center 75 of the frame, and in this embodiment, an adhesive is used.

[0038] In this way, the frame after adhesive application and welding is completed will be described in detail, particularly regarding the areas where the sheet metals are in contact with each other. Figure 11 shows the contact area 40 between the front plate 27 and the main stay 29. Near both ends of the contact area 40, which is indicated by the diagonal lines, there are welding positions 50a and 50b, and adhesive has been applied to a total of 10 locations, indicated by 60d to 60q, in the area between these two points. In other words, the front plate 27 and the main stay 29 are joined by welding and adhesive.

[0039] In the contact area 41 between the front plate 27 and the substrate stay 31, there are welding positions 50c and 50d near both ends of the contact area 41, and adhesive is applied to a total of three locations 60a to 60c in the area between these two points. In other words, the front plate 27 and the substrate stay 31 are joined by welding and adhesive.

[0040] In the contact area 42 between the rear plate 28 and the main stay 29 shown in Figure 12, there are welding positions 50e and 50f near both ends of the contact area 42, and adhesive is applied to a total of 10 locations, indicated by 60r to 60zz, within the area between these two points. In other words, the rear plate 28 and the main stay 29 are joined by welding and adhesive.

[0041] Here, we will explain the delamination resistance of the sheet metal joint. Figure 13 shows an example of a case where a delamination force acts on the front plate 27 and the main stay 29, specifically when the delamination force acts in the direction of arrow A. As shown in Figure 13, when a delamination force acts on the ends of the front plate 27 and the main stay 29, the maximum value of the delamination force is generally concentrated at the left end (negative X direction) of the contact area 40. However, since the front plate 27 and the main stay 29 are welded at the welding position 50a, they have sufficient resistance to a given delamination force. Therefore, a large delamination force does not directly act on the adhesive positions 60d, 60e, etc., located to the right of the welding position 50a. This compensates for the fact that the adhesive is not particularly strong against forces in the direction of delamination.

[0042] As another example, Figure 14 assumes a case where a peeling force B acts near the center of the contact area 40 between the front plate 27 and the main stay 29. Here, we will further explain using Figure 15, which is viewed from the cross-sectional line SS. In Figure 15(a), a part of the main stay 29 is bent to form a curved portion, following the surface of the front plate 27 which is on a plane. The image shows adhesive 60h applied between the front plate 27 and the main stay 29. If a peeling force B acts from this state as shown in Figure 15(b), the curved portion of the main stay 29 will deform first, and then the force will concentrate on the upper end of the adhesive 60h, making it easy to peel off starting from the upper end. For this reason, in this embodiment, as shown in Figure 15(c), the adhesive application position is adjusted to be located at the base of the curved portion of the main stay 29. As a result, although the peeling force B is transmitted through the main stay 29, deformation of the curved portion of the main stay 29 does not occur, and the force is distributed throughout the entire area where the adhesive 60h is applied, so peeling does not occur. In particular, the area at the base of the bend cannot be fastened with welding or screws, so the unique effects of adhesives can be obtained there.

[0043] Furthermore, using adhesive eliminates the need for drilling holes, as required when fastening with screws, and allows for a smooth, flat surface without welding marks. As a result, in areas like the cartridge insertion port, which are accessed by the user, it is possible to ensure high rigidity while maintaining a clean surface.

[0044] In this embodiment, it takes several minutes from the start of welding the frame until it is completed, but by the time the welding is complete, the applied adhesive has also solidified and reached a state of practical strength. Since there is no need to individually allocate time for the adhesive to reach practical strength, it is efficient in terms of production. In other words, it does not interrupt the subsequent process of attaching further components to the frame 200 and assembling the image forming apparatus 100.

[0045] The area between the multiple welding positions 50a to f mentioned above lacks holes or spaces for an automated welding robot. Conventionally, this would have required the use of fasteners such as screws. However, by using adhesive as in this embodiment, it is possible to efficiently fasten the sheet metals together. Furthermore, compared to screw fastening, the continuous application of adhesive by an automated application robot reduces working time and material costs, resulting in cost savings. In addition, it has been found that the shear strength of adhesively joined sheet metals is 5 to 20 times greater than the shear strength of screws (i.e., the shear force maintained by the frictional force between sheet metals held together by screws). Therefore, it is possible to eliminate the phenomenon called screw slippage due to impact, which is a drawback of fasteners such as screws.

[0046] Furthermore, although adhesives do not have particularly high strength against forces in the direction of delamination, the welding at both ends of the contact area between the two sheet metal pieces prevents damage due to adhesive delamination.

[0047] Furthermore, since the adhesive itself is a non-conductive material, if the stay and the side plate are fixed with adhesive at all points, a thin film will be formed between them, which may prevent current from flowing properly from the stay to the side plate. In other words, there is a possibility that grounding cannot be achieved. Since the board stay 31 that supports the high-voltage power supply board 13 needs to be properly grounded, in this embodiment, such problems are prevented by welding both ends of the contact area 41 (shown in Figure 11) between the front side plate 27 and the board stay 31. Here, conductivity is ensured at welding positions 50c to d.

[0048] In this embodiment, the frame 200 includes both sheet metal assemblies joined by welding and adhesive, as well as sheet metal assemblies joined by welding alone. The optimal joining method should be selected based on the members and configurations supported by the sheet metal.

[0049] Based on the above, according to this embodiment, in a configuration in which the frame of an image forming apparatus is assembled using an adhesive, it is possible to reduce the weight of the frame while ensuring the frame rigidity in the direction of adhesive peeling.

[0050] In this embodiment, by joining two sheet metal pieces using an automated welding robot in addition to adhesive, the frame's rigidity in the direction of adhesive peeling is ensured while reducing the frame's weight. In particular, by welding the two sheet metal pieces so that they are sandwiched between the points where they are joined by adhesive, the force acting in the peeling direction is mainly received at the welded point, resulting in a configuration that makes the adhesive less likely to peel than in conventional designs.

[0051] Furthermore, since welding machines, such as automated welding robots, have limitations on the area they can access, this embodiment features a carefully designed welding position for joining the two sheet metal pieces and an adhesive application position. Specifically, as described above, welding is performed by sandwiching the area where the two sheet metal pieces are joined by the adhesive, and the welding position is located closer to the edge of the sheet metal compared to the adhesive application position. As a result, the configuration allows welding machines, such as automated welding robots, to access the area relatively easily.

[0052] (modified version) In the above embodiment, the sheet metal only had markings indicating the application position, but if necessary, the sheet metal may be subjected to drawing, embossing, or other processes at the application position. By applying these processes to both or at least one of the two sheet metals to be joined, it is expected that the adhesive strength between the sheet metals will be improved. Whether or not to perform these processes can be appropriately selected while considering the balance with the freedom of space and shape.

[0053] Furthermore, in the above embodiment, adhesive was applied in a dotted pattern to multiple locations on both side plates. However, this is not the only option. As shown in Figure 16, the adhesive may be applied in a linear pattern. Compared to the process shown in Figure 4, the bonding area can be increased, making it possible to create an even higher-strength frame rigidity.

[0054] Figure 17 shows the state of the contact area 40 between the front plate 27 and the main stay 29, and the contact area 41 between the front plate 27 and the base plate stay 31. In the area between welding positions 50a to 50f, there are no holes or spaces for an automatic welding robot to enter, so conventionally it would have been necessary to use fastening members such as screws. However, as in this modified example, by using adhesive, it is possible to efficiently join the sheet metals together.

[0055] Furthermore, while the above embodiment involved applying the adhesive first before assembling and welding the sheet metal, this is not necessarily the only method. It is also possible to inject the adhesive into the gap between the two sheet metal pieces after the welding process. For example, by injecting the adhesive later into the base of the bent portion of the main stay 29 in Figure 15(c), the effect of adhesive application can be expected. When injecting, a relatively low viscosity adhesive of about 3000 to 10000 [mPa·s] should be used, and it should be allowed to penetrate between the sheet metal pieces using gravity and capillary action.

[0056] Furthermore, in the above embodiment, as shown in Figure 11, for example, both ends of the contact area 40 between the front plate 27 and the main stay 29 were welded, but this is not limited to this. The adhesive may be applied to the area between the two welding positions, and the adhesive may also be applied to the outside (end side) of the welding positions. In other words, the present invention does not exclude configurations in which the adhesive is applied to areas not between the two welding positions.

[0057] Furthermore, although the above embodiment describes an electrophotographic image forming apparatus 100, the present invention is not limited to this. The present invention can also be applied to assembling the frame of an image forming apparatus employing a different printing method, such as an inkjet method or an offset printing method. [Explanation of symbols]

[0058] 6 Image forming unit 27 Front side panel 28 Posterior plate 29 Main Stay 100 Image forming apparatus

Claims

1. An image forming unit that forms an image on a recording material; A first sheet metal and a second sheet metal provided to face each other with the image forming unit interposed therebetween; In an image forming apparatus having a third sheet metal provided between the first sheet metal and the second sheet metal and joined to each of the first sheet metal and the second sheet metal, The first sheet metal and the third sheet metal are welded at at least two welding positions; An adhesive is applied between the first sheet metal and the third sheet metal so that the first sheet metal and the third sheet metal are joined; The image forming apparatus, wherein the adhesive is applied between the at least two welding positions.

2. The two welding positions are located at both ends of a region where the first sheet metal and the third sheet metal are in contact with each other, and the adhesive is applied only in a range sandwiched by the two welding positions between the first sheet metal and the third sheet metal. The image forming apparatus according to claim 1, characterized in that.

3. A part of the third sheet metal is bent along the surface of the first sheet metal, The image forming apparatus according to claim 1, wherein the adhesive is applied to a bent portion of the third sheet metal.

4. The second sheet metal and the third sheet metal are welded at at least two welding positions; The adhesive is applied between the second sheet metal and the third sheet metal so that the second sheet metal and the third sheet metal are joined; The image forming apparatus according to claim 1, wherein the adhesive is applied between the at least two welding positions where the second sheet metal and the third sheet metal are welded.

5. The image forming unit is a cartridge including a photoreceptor, a charging unit that charges the photoreceptor, and a developing unit that develops an electrostatic latent image formed on the photoreceptor, and the cartridge is detachably provided with respect to a device main body of the image forming apparatus. The first sheet metal and the second sheet metal include positioning portions that come into contact with ends of the cartridge in the longitudinal direction of the cartridge to position the cartridge, and the third sheet metal supports the cartridge. The image forming apparatus according to any one of claims 1 to 4, characterized in that.

6. Having a power supply substrate that generates a voltage applied to the image forming unit, The image forming apparatus according to any one of claims 1 to 4, wherein the third sheet metal supports the power supply substrate.

7. A method of manufacturing a frame of an image forming apparatus, comprising: a coating step of applying an adhesive to the surfaces of the first sheet metal and the second sheet metal respectively; an assembling step of assembling the first sheet metal and the second sheet metal so as to sandwich a third sheet metal, and joining the first sheet metal and the second sheet metal to the third sheet metal via the adhesive; a first welding step of welding the first sheet metal and the third sheet metal at at least two locations so as to sandwich the position where the first sheet metal and the third sheet metal are joined by the adhesive; a second welding step of welding the first sheet metal and the third sheet metal at at least two locations so as to sandwich the position where the first sheet metal and the third sheet metal are joined by the adhesive; A manufacturing method characterized by comprising the above.

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