JP2003283154A - Connection structure of sheet-metal component and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain grounding and EMI resistance similar to that of a constituted body consisting of the present zinc-plated steel plate by surely realizing continuity at the connection surface when the sheet-metal components consisting of a chromium-free steel sheet provided with insulated resin film on the surface layer of metal portion thereof are connected using the fasteners such as screws, rivets or the like. <P>SOLUTION: An assembly is formed by connecting at least two sheet-metal working components 21, 22 at the connecting surfaces 21a, 22a and at least any one connecting surface is provided with the insulation resin film 23. In this assembly, a knurled-area forming region 25 is provided at the connecting surface of at least one sheet-metal working component and the metal portions of double-side components are coupled directly via the knurled-area forming region. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a joint portion of a structure forming a skeleton of various electronic devices and mechanical devices, and in particular, metal parts having an insulating resin film on the surface layer are screwed together,
The present invention relates to a connecting structure of sheet metal parts capable of reliably connecting metal parts to each other to ensure electrical connection when they are connected by a rivet or the like.

[0002]

2. Description of the Related Art Image forming apparatuses such as copiers, printers, and facsimiles, information processing apparatuses such as computers, electronic equipment such as communication equipment, electric equipment, mechanical equipment, and the like have various parts in a metal structure forming a skeleton thereof. , Unit etc.
Further, it has a structure in which an exterior body is attached to the outer surface thereof.
Currently, metal structures use screws, rivets, or other connecting members between the connecting surfaces of multiple sheet metal parts, or by welding, etc.
Built by combining, but against static electricity,
The metal structure is also used as a grounding means for EMI countermeasures. As a conventional sheet metal part, a zinc-treated steel plate having a hexavalent chromium film having a rust preventive effect on the surface is used, but hexavalent chromium causes a deterioration of the environment. There is an urgent need to review its use. From such a point, recently, a steel plate (chromium-free steel plate) having a resin coating layer containing no hexavalent chromium (chromium-free steel plate) has been developed as a substitute for the zinc-treated steel plate, and gradually used for the structure of equipment. It has become so. This resin coat layer is
It is a thin insulating resin film with a thickness of about several μm, and has a rust preventive effect. However, when sheet metal parts made of a chrome-free steel sheet having an insulating resin film on the surface layer are joined together, conduction failure is likely to occur at the joining surface due to the insulating resin film interposed on the joining surface, and this kind of The groundability of the entire structure composed of sheet metal parts is somewhat difficult, and there is a problem in terms of measures against static electricity and EMI.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and screws sheet metal parts made of a chrome-free steel plate provided with an insulating resin film on the surface of the metal portion with screws,
When constructing a metal structure of a device that is connected by using a connecting member such as a rivet, it is possible to reliably ensure continuity on the connecting surface, and to have the same groundability and EMI resistance as the current structure made of zinc-treated steel sheet. The purpose is to ensure sex.

[0004]

In order to solve the above-mentioned problems, the invention of claim 1 is a combination body in which at least two sheet metal parts are connected to each other by their respective connection surfaces, and at least one of the connection surfaces. Characterized in that a knurling forming area is arranged on the joining surface of at least one of the sheet metal parts, and the metal parts of both sheet metal parts are directly joined via the knurling forming area. To do. When the structure constructed by connecting the sheet metal parts to each other is also used as the grounding means, it is necessary to secure the conduction at the connecting surface of the sheet metal parts. However, for sheet metal parts such as chrome-free steel plates that have an insulating resin film on the surface, even if they are screwed or riveted as they are,
It is not possible to ensure electrical continuity by directly contacting the metal layers between the bonding surfaces. In view of this, in the present invention, a knurled region is formed on at least one of the coupling surfaces, and a large number of sharp small projections forming the knurled region pierce the resin film to expose the metal layer. At this time, the knurled area is formed on either one of the bonding surfaces even when the resin film is formed on only one of the bonding surfaces, as well as when both insulating surfaces are coated with the insulating resin film. By forming the, it is possible to surely secure conduction between both coupling surfaces. For this reason, the grounding property is enhanced, and static electricity measures,
It can be useful for countermeasures against electromagnetic interference caused by electromagnetic waves. In addition, since the knurled region has a high coefficient of friction, it is effective in preventing the slippage, slippage and the like between the coupling surfaces and increasing the coupling force. The sheet metal part is a member made of various metal materials, and the joining surface refers to a surface for joining the sheet metal parts. Further, the combined body is a structure having a required shape constructed by connecting a plurality of sheet metal parts. With the knurled area, regardless of the processing method,
A region subjected to roughening is shown. According to a second aspect of the present invention, in the first aspect, the sheet metal parts each have a coupling hole on a coupling surface thereof, and a coupling member having a large-diameter head is inserted and fixed in each coupling hole. In the joined body in which the parts are joined, the knurl formation region is formed on the outer periphery of the joining hole, and the area thereof is configured to be within the area of the head seat surface of the fastening member. According to this, since the diameter of the knurling region is smaller than the diameter of the head of the screw as the coupling member, the screw tightening torque more reliably acts on the knurled region portion, and the small protrusions cause the mating sheet metal parts. It can bite into the connecting surface of and secure the ground. In addition to improving the grounding property on the joint surface between the sheet metal parts, it is possible to enhance the mechanical joint strength.

According to a third aspect of the present invention, there is provided a joined body in which at least two sheet metal parts are joined by their respective joining surfaces.
An insulating resin film is provided on at least one of the coupling surfaces,
Further, each of the coupling surfaces has a coupling hole, and one of the coupling surfaces has a half-blanked portion centered on the coupling hole. Although the work of forming the knurled area is a little laborious,
The half blanking is a simpler working operation, and the half blanking can remove the insulating resin film, and the insulating resin film provided on the mating coupling surface can be removed to secure the conduction. Become. That is, it is possible to secure the ground contact property by a half blanking process that is simpler than the knurling process. According to a fourth aspect of the present invention, in the third aspect, the diameter of the semi-blanked shape portion is set to be equal to or larger than a large-diameter head portion of the coupling member inserted and fixed in each coupling hole. Since the diameter of the half blank shape part is larger than the head diameter of the screw as the connecting member, the screw tightening torque acts more reliably on the half blank part, and the metal edge bites into the mating sheet metal. ,
You can surely ground. The invention of claim 5 is
In a joined body in which at least two sheet metal parts are joined to each other by their respective joining surfaces, an insulating resin film is provided on at least one of the joining surfaces, and each joining surface has a joining hole. The connecting surfaces of the respective sheet metal parts are connected via a washer. By interposing the chrysanthemum washer (chrysanthemum washer), it is possible to improve the earthing property without processing the sheet metal part. The chrysanthemum washer may be any washer that can break through the insulating resin film. An image forming apparatus according to a sixth aspect of the present invention is characterized by using a combination having the sheet metal component connection structure according to any one of the first to fifth aspects. According to this, it is possible to provide the image forming apparatus provided with the metal structure having the excellent antistatic effect, the electromagnetic interference prevention effect, and the coupling portion reinforcing effect described in the above claims.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the embodiments shown in the drawings. FIG. 1 is a schematic configuration diagram of an image forming apparatus provided with a metal structure (frame) adopting the sheet metal part coupling structure of the present invention. The image forming apparatus includes a paper feeding unit A, an image forming unit B, a writing unit C, a reading unit D, an automatic document feeding device E, a post-processing device F, and the like. The document fed by the automatic document feeder E to the document reading position is read by the reading unit D, and the read document image is provided from the writing unit C to the image forming unit B as laser light. The image forming unit B forms an image on the sheet fed from the sheet feeding unit A. In the image forming process in the image forming section B, the latent image is written on the photoconductor of the photoconductor unit 1 by the laser light from the writing unit C, and the latent image is visualized by the developer from the developing section. The formed image is transferred to a sheet and fixed on the sheet with a fixing unit. After that, when the double-sided image is formed, the paper is sent to the duplexer 4 by the paper discharge separation unit 3, is sent to the upper paper discharge bin 5 when the upper paper is discharged, and is discharged to the finisher F via the relay unit 6 when the finisher is discharged. The manual feed section 7 can also be installed as an option. FIG. 2 is an exploded perspective view of a metal structure (frame) forming the skeleton of the image forming apparatus shown in FIG. The image forming apparatus includes a structure,
Electrical components and the like are often composed of sheet metal parts. The method of joining sheet metal parts is screwing, rivets, welding, etc.
It is decided in consideration of ease of assembly and economy. Here, a description will be given of an example of a connecting structure using screws (bolts) generally used as a connecting member. The rivet is the same as the screw. As shown in FIG. 2, a structure is formed by combining sheet metal parts of various shapes, such as a lateral stay-shaped part 11 and a face plate-shaped part 12, and connecting them with screws 13. At least a part of these sheet metal parts is made of a chrome-free steel plate having an insulating resin film on the surface of the metal part.

FIG. 3A is a perspective view showing an example of the coupling structure of the present invention, and FIG. 3B is a sectional view showing the coupling state. The coupling holes 21b and 22b are formed in the coupling surfaces 21a and 22a of the first sheet metal part 21 and the second sheet metal part 22, respectively.
Is formed so as to penetrate, and the screw 13 as a connecting member is inserted and fixed (screwed) in a state where both the connecting holes 21b and 22b are communicated with each other.
By doing so, the coupling surfaces 21a and 22a are fastened. The characteristic configuration of this coupling structure is that when at least one of the sheet metal parts has an insulating resin film formed on the coupling surface, one of the coupling surfaces is provided with a knurled forming region 25 that is knurled in advance. By doing so, the insulating resin film is pierced to expose the metal portion. That is, in the case where both the coupling surfaces 21a and 22a of the two sheet metal parts 21 and 22 both have the insulating resin film 23, of course, even when only one of them has the insulating resin film 23, either By forming the knurl formation region 25 on one of the bonding surfaces, it is possible to realize the direct bonding of the metal parts and to secure the conduction between both the bonding surfaces. For example, when only the joining surface 21a of the first sheet metal part 21 is knurled, even if the insulating resin film 23 is formed on this joining surface 21a, the resin film is partially removed by the knurling. As a result, the metal portion is exposed, so that the bonding surface 22a of the second sheet metal part component 22 is a metal surface, and even if the bonding surface 22a is provided with the insulating resin film 23, Numerous sharp small projections 25 that make up the knurled portion
Since "a" breaks through, it is possible to ensure continuity in any case. For this reason, the continuity between the assembled sheet metal parts is secured, which is convenient when it is desired to secure the ground using the structure for countermeasures against static electricity and EMI. Further, the knurled region also exerts an effect of increasing the bonding force between the bonding surfaces. Moreover, the same effect can be exhibited when the knurling region 25 is provided only on the coupling surface 22a of the second sheet metal part 22. Also, both coupling surfaces 21a, 22a
The knurled regions 25 may be provided in both of the above. In this embodiment, the range in which the knurled area 25 is formed is the area range corresponding to the mating coupling surface 22a. As is well known, the knurling process is a process in which a knurling tool is attached to a lathe and the like and the desired knurling is formed on the surface of the workpiece while rotating the knurling tool.

Next, FIG. 4 is an exploded perspective view of a sheet metal part coupling structure according to a second embodiment of the present invention. The feature of this embodiment is that the knurl forming area 25 is formed in the coupling hole 21b.
Formed within a predetermined range on the outer periphery of the
Is that the area is within the area of the seat surface of the head 13a of the screw 13 as the fastening member. That is, when the seat surface of the head portion 13a and the knurled region 25 are both circular, the diameter R of the knurled region 25 is R.
And the diameter r of the head 13 are set such that R ≦ r. In this way, the screw head 13
When the diameter r of the seat surface of a and the diameter R of the knurl formation region have the above-described relationship, the screw tightening force spreads within the range of the knurl formation region, and the small protrusion 25a surely becomes the insulating resin. Break through the membrane 23 to ensure continuity. The bite into the mating mating surface by the small projection 25a not only secures conduction, but also prevents slippage between the mating surfaces and enhances the fastening force. Next, FIGS. 5 (a) and 5 (b) are an exploded perspective view showing a joining structure of sheet metal parts according to a third embodiment of the present invention, and a sectional view showing a joined state. That is, the joint structure according to this embodiment is a joint body in which two sheet metal parts 21, 22 at least one of which is made of a chrome-free steel plate are joined by respective joint surfaces 21a, 22a, and each joint surface is respectively joined. It has holes 21b and 22b. Further, either one of the coupling surfaces 21a and 22b (in this example,
21a) is formed with a half-blank shaped portion 30 centered on the coupling holes 21b, 22b. When the half-blanked portion 30 is formed on the coupling surface having the insulating resin film, the resin film in the portion corresponding to the half-blanked portion 30 is removed and the metal portion is exposed, while the edge portion 30a is It penetrates the resin film on the mating surface of the other party and plays a role in ensuring conduction. That is, as shown in FIG. 5B, both coupling holes 21b, 2
When the two joining surfaces 21a and 22a are brought into a joined state by inserting and screwing the screw 13 in a state in which the 2b are in communication with each other, the edge portion 30a of the half-blank shaped portion 30 has the opposite resin film 23.
It digs into and breaks through it, making both mating surfaces conductive. That is, when the central portion of the half-blanked joining surface is screwed, the screwing force concentrates on the half-blanked edge portion (the portion where the metal layer is exposed) 30a and cuts into the mating joining surface. , More stable conduction is secured. In this case, it is better to make the half-drawing diameter larger than the screw head diameter.
The elasticity of sheet metal parts can be used, and the earth effect is stable. Thus, as a countermeasure against static electricity and EMI, this structure is suitable for grounding the metal structure made of sheet metal parts, and also has the effect of preventing slippage and slippage of the coupling surface. As is well known, the half blanking is a processing method in which a dedicated processing jig is attached to a lathe and rotated to remove a part of the wall thickness of the workpiece.

Next, FIG. 6 is a sectional view showing a joining structure of sheet metal parts according to a fourth embodiment of the present invention. The insulating resin film 23 is provided on at least one of the joining surfaces 21a and 22a.
And a structure in which a chrysanthemum washer 35 is interposed between the connecting surfaces of the sheet metal parts when the sheet metal parts 21 and 22 having the connecting holes 21b and 22b respectively on the connecting surfaces are connected by the screws 13. Target. The chrysanthemum washer 35 has a shape in which a plurality of claws are projected at a predetermined pitch on the outer circumference of the thin-walled disc portion,
It has a configuration in which the tips of the claws are projected in one surface direction. For this reason, when the chrysanthemum washer 35 is pressure-welded between the two coupling surfaces, the protrusions at the tips of the claws cause the insulating resin film 23 on one coupling surface.
Can be broken through to ensure continuity. When the chrome-free sheet metal parts covered with the insulating resin film are fastened with the chrysanthemum washer 35 interposed therebetween, the chrysanthemum washer penetrates the insulating resin film and metal It is possible to secure the grounding property by making contact. The use of the chrysanthemum washer 35 does not require extra working work such as knurling and half blanking, and is therefore convenient when joining unprocessed existing sheet metal parts. However, since the dimensions of the connecting portion are changed by the thickness of the chrysanthemum washer, it can be applied only to a portion where the dimensions may be changed.

[0010]

As described above, according to the present invention, when sheet metal parts made of chrome-free steel plate having an insulating resin film on the surface of a metal portion are joined together by using joining members such as screws and rivets. To ensure the continuity of the connecting surface,
It is possible to secure the same groundability and EMI resistance as those of the current structure made of zinc-treated steel sheet. According to the invention of claim 1, when the sheet metal component having the insulating resin film formed on the surface of the metal layer is joined, the knurled region is formed on at least one of the joining surfaces to form the knurled region. Since the metal film is exposed by breaking through the resin film with the small projections with sharp angles, it is possible to improve the grounding property and to be useful for the measures against static electricity and the electromagnetic interference due to electromagnetic waves. In addition, since the knurled region has a high coefficient of friction, it is effective in preventing the slippage, slippage and the like between the coupling surfaces and increasing the coupling force. According to the invention of claim 2, since the diameter of the knurling region is smaller than the diameter of the head portion of the screw as the coupling member, the screw tightening torque acts more reliably on the knurled region portion, and the small protrusion Can bite into the mating surface of the mating sheet metal part and reliably secure the ground.
It is possible not only to improve the grounding property on the joint surface between the sheet metal parts but also to enhance the mechanical joint strength. According to the third aspect of the invention, since one of the bonding surfaces is half-blanked, the insulating resin film can be removed by half-blanking, and the insulating resin film provided on the mating bonding surface can be removed to conduct electricity. Can be secured. That is, it is possible to secure the ground contact property by a half blanking process that is simpler than the knurling process. According to the invention of claim 4, since the diameter of the half-blank shape part is larger than the head diameter of the screw as the coupling member, the screw tightening torque more reliably acts on the half-blank part, and the metal is exposed. It is possible to bite into the mating sheet metal at the edge part and securely ground. According to the invention of claim 5,
By interposing the chrysanthemum washer (chrysanthemum washer), it is possible to improve the earthing property without processing the sheet metal part. According to the invention of claim 6, it is possible to provide the excellent antistatic effect, the electromagnetic interference blocking effect, and the reinforcing effect of the coupling portion described in each of the above claims.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of an image forming apparatus provided with a structure composed of sheet metal parts of the present invention.

FIG. 2 is an exploded perspective view showing an example of a metal structure (combined body) included in the image forming apparatus of FIG.

FIG. 3A is a perspective view showing an example of the coupling structure of the present invention, and FIG. 3B is a sectional view showing a coupling state.

FIG. 4 is an exploded perspective view of a sheet metal part coupling structure according to a second embodiment of the present invention.

5A and 5B are an exploded perspective view showing a joining structure of sheet metal parts according to a third embodiment of the present invention, and a sectional view showing a joined state.

FIG. 6 is a cross-sectional view showing a joining structure of sheet metal parts according to a fourth embodiment of the present invention.

[Explanation of symbols]

A paper feeding unit, B image forming unit, C writing unit, D reading unit, E automatic document feeding device, F
Post-processing device, 1 photoconductor unit, 3 paper discharge separation unit, 4
Double sided device, 5 upper discharge bin, 6 relay unit, 7 manual feed part, 13 screw (coupling member), 13a head part, 21
First sheet metal part, 22 Second sheet metal part, 21a, 22
a coupling surface, 21b, 22b coupling hole, 23 insulating resin film, 25 knurled region, 25a small protrusion, 3
0 Half blank shape part, 30a edge part, 35 chrysanthemum washer.

Continued front page    F-term (reference) 2H171 FA01 FA05 FA07 FA26 GA18                       GA31 HA18 HA19 HA22 HA37                       KA11 KA28 MA05 MA07 PA07                       PA12 QB15 QB18 QC03 QC36                       RA01 RA03 RA05 SA11 SA14                       SA18 SA22 SA26 UA02 UA06                       UA14 UA22 UA24 VA02 VA06                 4E360 AB02 AB12 BA08 ED02 ED06                       ED27 EE13 EE15 FA08 GA32                       GA34 GB48 GC02 GC16

Claims (6)

[Claims] 1. A combined body in which at least two sheet metal parts are joined together by their respective joining surfaces, wherein at least one of the joining surfaces is provided with an insulating resin film, at least one of the sheet metals. A sheet metal part joint structure characterized in that a knurling forming region is arranged on a joint surface of the parts, and the metal parts of both sheet metal parts are directly joined through the knurling forming region. 2. A combined body in which both sheet metal parts are joined by inserting and fixing a joining member having a joining hole on the joining surface of each of the sheet metal parts and having a large-diameter head. The joining of the sheet metal parts according to claim 1, wherein the knurl forming region is formed on the outer periphery of the joining hole, and the area thereof is configured to be within the area of the head seat surface of the fastening member. Construction. 3. A joined body in which at least two sheet metal parts are joined together by their respective joining surfaces, and at least one of the joining surfaces is provided with an insulating resin film, and each joining surface has a joining hole. And a half-blanked portion centering on the coupling hole is formed on either one of the coupling surfaces. 4. The sheet metal part according to claim 3, wherein a diameter of the half blank shape portion is set to be equal to or larger than a large-diameter head portion of a joining member inserted and fixed in each joining hole. Bond structure. 5. A joined body in which at least two sheet metal parts are joined together by their respective joining surfaces, and at least one of the joining surfaces is provided with an insulating resin film, and each joining surface has a joining hole. The sheet metal component coupling structure according to claim 1, wherein the coupling surfaces of the respective sheet metal components are coupled through a chrysanthemum washer. 6. An image forming apparatus comprising a combined body having the structure for connecting sheet metal parts according to claim 1. Description: