JP6008615B2 - Sheet metal fastening part structure - Google Patents

Description

  The present invention relates to a fastening portion structure using a thin steel plate in a mechanical apparatus such as an image forming apparatus such as a printer, a facsimile machine, a copying machine, or a multifunction machine having these functions.

  Recent mechanical devices such as printers and copiers are expected to have an energy saving effect due to weight reduction, and are required to reduce the thickness of the metal plates constituting the device. On the other hand, in order to maintain the strength of the housing of the device or to suppress the emission of electromagnetic noise inside and around the device by making a stable electrical frame ground connection, it is fastened with the metal plate that constitutes the device A predetermined fastening force is required for the contact portion of the member to be formed. That is, a contact portion (hereinafter referred to as “fastening portion”) for fastening each of the metal plate to be fastened (hereinafter referred to as “fastening material”) and a member fastened to the fastening material (hereinafter referred to as “fastened material”). .) Requires a predetermined fastening force. When fastening a fastening material and a material to be fastened with a screw, it is necessary to fasten the screw with a predetermined fastening torque. At that time, the fastening portion is required to have a breaking torque that can withstand the fastening torque.

  In the case where the conventional fastening material has a certain thickness, the material can be squeezed out by burring to ensure the squeezed height (hereinafter referred to as “burring height”). Thereby, the squeezed-up burring height hits the screw fitting portion, so that an effective screw fitting length can be obtained. Even if an electric screwdriver is used to assemble the machine at the factory or replace it in the market by obtaining an effective screw fitting length, the impact generated when tightening the screw is absorbed by the effective screw fitting length and excessive. Can suppress the torque and prevent the fastening part from being broken.

  However, when the plate thickness of the fastening material is thin, even if the material is squeezed out by burring, the total screw fitting length is shortened as the plate thickness is reduced. For this reason, an excessive torque is applied to the screw thread without being able to absorb the impact generated when the screw such as the electric screwdriver is tightened, and the screw thread is destroyed. Moreover, since the plate | board thickness of a fastening material is thin, a burring periphery part cannot endure a general impact and becomes easy to deform | transform.

  In order to suppress such deformation of the fastening part with the thin plate thickness of the fastening material, means to suppress the impact force by lowering the rotation speed when tightening the screw with an electric screwdriver etc. can be considered, but screw fastening work productivity Will lead to a decline.

  As a countermeasure against these problems, Patent Document 1 discloses a means for disposing a rubber elastic member between a material to be fastened and a screw head, and tightening the screw by applying torque to the screw while compressing the elastic member. Proposed. In this means, the elastic member is elastically deformed and crushed, so that excessive torque is absorbed, and the fastening portion is prevented from being broken.

JP 2006-177438 A

  However, as a measure proposed in Patent Document 1, a means that requires an elastic member separately from the fastening material and the fastened material may forget to attach the elastic member when assembling. In addition, the increase in parts leads to an increase in cost.

  Further, in an electrical unit in which an electrical base is installed in a printer, a copying machine, or the like, screw fastening is used because it is desired that it is easy to attach and remove because of component replacement in the market. Conventionally, in places where it is necessary to establish electrical connection between the fastening material and the material to be fastened, such as such an electrical unit, the fastening material and the fastening material are fastened by fastening the fastening material and the material to be fastened with screws. Direct electrical connection is made at the contact portion of the material to be fastened. That is, the fastening material and the material to be fastened are electrically connected through the contact portion between the material to be fastened and the screw head and the contact between the screw portion of the screw and the female screw portion of the fastening material. Even in a member having a place where it is necessary to establish an electrical connection between a fastening material and a material to be fastened, such as this electrical unit, it may be configured with a thin plate thickness in order to reduce weight and weight in recent years. preferable. However, in the means proposed in Patent Document 1, non-conductive rubber is used between the screw and the material to be fastened, and conductivity at the fastening portion cannot be expected. Even if conductive rubber is used, the electrical conductivity is inferior to the contact between metals, and the electrical connection between the fastening material and the material to be fastened becomes unstable.

  Therefore, the purpose of the present invention is to maintain work productivity at the time of screw tightening without increasing the number of parts, and even in the case of a fastening part that requires a stable electrical connection between the fastening material and the material to be fastened, It is an object of the present invention to provide a thin plate metal fastening part structure that can be fastened with a predetermined fastening torque.

The above object is achieved by the fastening portion structure according to the present invention. In summary, the present invention provides a screw having a screw head and a screw screw portion, a fastening material having a screw engaging portion for screwing with the screw screw portion, and a seat surface of the screw and the fastening material. pinched, the fastening portion structure having a fastened member is fastened by the screw, the screw head has a Bisutsuba portion that projects outward in the radial direction of the Bisuneji portion, wherein the fastening member, the The screw includes a hole through which the edge of the hole includes an elastically deformable folded portion having a shape folded back to the screw head side, and the folded portion is formed at the tip of the folded portion. A first corner formed on the first surface facing the seat surface, and a second corner formed on the second surface disposed on the opposite side of the first surface at the tip of the folded portion; The first corner portion has a direction to bite into the seating surface. In one that contacts the Bisutsuba portion, the second corner is a fastening portion structure characterized in that it is configured in a non-contact with the seat surface.
According to another aspect of the present invention, a screw having a screw head and a screw screw part, a fastening material having a screw engaging part for screwing with the screw screw part, and a seat surface of the screw and the fastening material A screw to be fastened by the screw, and the screw head has a screw flange protruding outward in the radial direction of the screw screw portion. A step of forming a hole in the fastened material, a step of folding the periphery of the hole of the fastened material to the screw head side to form a folded portion that can be elastically deformed, and the screw at the tip of the folded portion A first surface formed on the first surface facing the seat surface is brought into contact with the screw flange portion in a direction to bite into the seat surface of the screw, and a second surface disposed on the opposite side to the first surface. The second corner portion formed in the non-contact with the seating surface In state method for producing a fastening material, characterized in that it and a step of screwing the screws into the threaded engagement portion is provided.

  According to the present invention, it is possible to maintain work productivity at the time of screw tightening without increasing the number of parts, and even in the case of a fastening part that requires a stable electrical connection between the fastening material and the material to be fastened. It is possible to provide a thin plate metal fastening portion structure that can be fastened with a fastening torque.

It is a schematic sectional drawing which shows one Example of the fastening part structure of this invention. It is a schematic sectional drawing of the conventional fastening part structure. It is a schematic sectional drawing of the fastening part structure in the other Example of this invention. It is a comparison figure of destruction torque effect in the example and comparative example of the present invention.

  Hereinafter, the fastening part structure according to the present invention will be described in more detail with reference to the drawings.

Example 1
FIG. 1 is a schematic sectional view showing an embodiment of the structure of the fastening portion 90 of the present invention.

The screw 10 has a screw head 11 and a screw screw portion 12. In this embodiment, diameter Bisuneji portion 12 side of the screw head 11 is large, Bisutsuba portion 13 are integrally formed. The screw flange 13 forms a part of the screw head 11 and forms a seat surface portion 11 b of the screw head 11. A cross hole shape (not shown) for rotating the screw 10 with a cross driver or the like is formed in the top 11 a of the screw head 11 at one end of the screw screw portion 12 of the screw 10. A male screw which is a screw thread is formed on the outer peripheral surface of the screw screw portion 12. As described above, the screw flange portion 13 constituting the seat surface portion 11b of the screw head 11 is disposed on the screw screw portion 12 side of the screw head 11, and has a diameter perpendicular to the longitudinal direction of the screw screw portion 12 and other screw head portions. It has a flange shape with a larger diameter.

The material to be fastened 30 which is a metal plate such as a thin steel plate has a folded shape (folded portion) 41 and a folded gap portion 42 formed by folding back the end portion of the screw hole 31 (the outer edge portion of the screw hole ) . The fastening material 20 which is a metal plate such as a thin steel plate has a burring portion 21 in which a part of the fastening material 20 is squeezed to a burring height 22 by burring. The burring portion 21 and the screw hole 31 of the material to be fastened 30 are overlapped. The burring portion 21 has a screw engaging portion (hereinafter referred to as “female screw portion”) 23 in which a female screw shape is formed in advance.

Then, by tightening the screw 10 by applying a fastening torque, the folded flange contact portion (first corner portion) 46 of the folded shape 41 comes into contact with the seat surface portion 11 b of the screw head 11, that is, the screw flange portion 13. The folded flange contact portion 46 contacts the screw flange portion 13 in the seat surface portion of the screw head 11, that is, in a region 48 smaller than the diameter of the screw flange portion 13. Further, in the fastening portion 90, the screw screw portion 12 formed on the screw 10 by applying a fastening torque is screwed with the female screw portion 23 which is a screw engaging portion formed in advance on the burring portion 21 of the fastening material 20. The

  In the present embodiment, the advantage of the folded collar contact portion 46 contacting the seat surface portion (screw collar portion) 13 of the screw head 11 will be described.

  FIG. 2 is a schematic cross-sectional view showing a structure of a fastening portion 90 in which a material to be fastened 30 is fastened to a fastening material 20 using a screw 10 which is conventionally performed.

  The screw 10 has a screw head 11 and a screw screw portion 12. In this example, the screw head 11 is integrally formed with a screw flange portion 13 which is located on the screw screw portion 12 side and forms the seat surface portion 11b of the screw head 11. The screw 10 has a cross hole shape (not shown) for rotating the screw 10 with a cross driver or the like at the top 11 a of the screw head 11 at one end of the screw screw portion 12. A male screw which is a screw thread is formed on the outer peripheral surface of the screw screw portion 12. The screw flange portion 13 has a flange shape having a diameter perpendicular to the longitudinal direction of the screw screw portion 12 and a larger diameter than other portions of the screw head 11.

  The fastening material 20 has a burring portion 21 in which a part of the fastening material 20 is drawn up to a burring height 22 by burring. The screw thread portion 12 is screwed with a female screw portion 23 which is a screw engaging portion in which a female screw shape is previously formed inside the burring portion 21. The female screw portion 23 of the fastening portion 90 by the screw 10 has a female screw shape cut in advance. However, when the screw 10 is a tapping screw, it is not necessary to provide a female screw shape in advance.

  The material 30 to be fastened has a screw hole 31, and is in contact with the screw flange 13 at a seat surface portion 11 b of the screw head 11 near the screw hole 31, that is, a flange contact portion (seat surface portion) 32 in this example. The fastening portion 90 is fastened by superimposing the female screw portion 23 of the fastening material 20 and the screw hole 31 of the fastened material 30 and tightening the screw 10 with fastening torque.

  When the screw 10 is tightened with an electric screwdriver or the like, the impact caused by the rotation of the bit shaft (not shown) of the electric screwdriver or the screw 10 causes the screw 10 to come into contact with the screw brim portion 13 at the brim contact portion 32 and at the same time the brim contact portion 32. And is transmitted to the female screw portion 23.

  Generally, the fastening torque (tightening torque) Tf applied to the screw 10 is the torque (screw portion torque) Tth generated at the female screw portion 23 and the torque (seat surface) generated at the contact portion 32 of the screw head 11 and the material 30 to be fastened. Torque) Tb.

Tf = Tth + Tb
It is.

  In the case where the fastening portion 90 has a certain thickness when fastened by the screw 10 of the fastening portion 90, it is possible to secure the burring height by squeezing the material by burring. Thereby, the squeezed-up burring height hits the screw fitting portion, so that an effective screw fitting length can be obtained. In this way, by obtaining an effective screw fitting length, even if an electric screwdriver is used when assembling the machine at the factory or when replacing it in the market, the effective screw fitting length can be reduced when tightening screws. And can suppress excessive screw portion torque Tth and prevent destruction of the fastening portion.

  Therefore, when the nominal diameter d of the screw 10 used in a conventional printer or copying machine is 3 to 4 mm and the plate thickness t of the fastening material 20 is 0.8 to 1.2 mm, it is sufficient. The burring height 22 can be secured. Since the female screw portion 23 can be secured long, the total screw fitting length is long, and the impact can be absorbed and fastened with an appropriate fastening torque Tf.

  However, as described above, in recent mechanical devices, it is required to thin the metal plate constituting the device. For example, in the case where the plate thickness t of the fastening material 20 is about 0.4 to 0.6 mm, the length of the female screw portion 23 is shortened as much as the plate thickness is reduced even if the material is drawn up by burring. The total screw fitting length is shortened by shortening the length of the female screw portion 23 engaged with the screw screw portion 12, and the conventional fastening portion structure shown in FIG. It becomes difficult. As a result, an excessive screw portion torque Tth is applied to the screw thread (not shown) of the female screw portion 23 and destroyed. Moreover, since the plate | board thickness of the fastening material 20 is thin, the surroundings of the burring part 21 cannot endure this impact, and become easy to deform | transform. Due to these factors, it is difficult to fasten the fastening portion 90 with an appropriate fastening torque Tf.

  On the other hand, when the screw 10 is further tightened after the folded shape 41 and the screw flange portion 13 which are the features of the present embodiment as shown in FIG. 1 come into contact with each other, the folded shape 41 is elastically deformed by having the folded gap portion 42. The elastic force can be applied to the screw portion 13. The elastic deformation direction that causes this elastic deformation is the axial direction of the screw thread portion 12 of the screw 10. Due to this elastic force, it is possible to suppress the impact generated when the screw is tightened by an electric screwdriver or the like. Excessive torque is not applied to the thread (not shown) of the female screw portion 23 and the periphery of the burring portion 21, so that the fastening portion 90 can be prevented from being broken and fastened with an appropriate fastening torque.

  In this embodiment, the shape that gives the elastic force to the screw flange portion 13 is the folded shape 41, but an oblique bent shape 41a that does not fold the screw hole end as shown in FIG. 3 may be formed. Even if the folded shape 41 is not formed, the same effect can be obtained by forming the slanted bent shape 41 a and providing the gap portion 42 a for elastic deformation between the fastening material 20.

  FIG. 4 shows the torque (hereinafter referred to as “breaking torque”) until the screw 10 slips when the screw thread of the female screw portion 23 or the periphery of the burring portion 21 is broken when tightened with an electric screwdriver. It is the result of having compared the structure of the conventional fastening part 90 with the structure of the fastening part 90 of the present Example shown in FIG.

  In both the conventional example and the present example, a screw having a nominal diameter d = 3 mm was used and the rotational speed of the electric driver was measured at 100 rpm. The fastening material 20 and the material to be fastened 30 are thin steel plates having a thickness t = 0.4 mm, the diameter of the screw hole 31 of the material to be fastened 30 is 4.5 mm, and the burring portion 21 is formed on the fastening material 20. did. A folded shape 41 having a folded portion diameter 48 of 6.2 mm was formed on the fastened material 30 of this example.

  As an effect of the present embodiment, the breaking torque is increased by 45% on average, and this result shows that the fastening can be performed with the fastening torque increased by 45% according to the structure of the fastening portion 90 of the present embodiment.

  Further, in the comparison in which the thickness t of the fastening material 20 and the material to be fastened 30 is 0.6 mm, this embodiment can be fastened with an average 50% increase in the breaking torque compared to the fastening portion 90 of the conventional example. It becomes. This result shows that the fastening portion structure of this embodiment can be fastened by increasing the fastening torque by 50%.

  As can be seen from these results, in the case where the folded shape 41 is formed at the screw hole end portion of the material to be fastened 30 measured this time, it is possible to tighten with a higher fastening torque than in the conventional example in which the folded shape 41 is not formed. Become.

  In addition, the same effect was able to be acquired also when the diagonal bending shape 41a was formed instead of the folding shape 41 in the screw hole edge part of the to-be-fastened material 30 shown in FIG.

  Further, in this embodiment, the fastening portion structure in which the female screw shape is formed in the screw engaging portion 23 of the fastening material 20 is provided. However, when the screw 10 is a tapping screw, the screw engaging portion 23 is provided with the female screw shape. There may be no structure.

Thus, in the means of the present invention, a part of the material to be fastened 30 is used as means for improving the fastening torque. For this reason, even if it is a case where the plate | board thickness of the fastening material 20 or the to-be-fastened material 30 is thin, even if it does not pinch | interpose the elastic member by other members like patent document 1, the appropriate fastening force of a fastening part is ensured. be able to. As a result, not only the casing (fastened product) of the machine device with a thin plate thickness but also the fastened portion requiring electrical conductivity such as an electrical unit (fastened product) while securing an appropriate fastening force. The electrical connection in can be stabilized. Further, since no other member is sandwiched, forgetting to assemble the parts can be prevented, and the cost for the other member can be reduced.

DESCRIPTION OF SYMBOLS 10 Screw 11 Screw head 11a The top part of screw head 11 11b The seat surface part of screw head 11 12 Screw screw part 13 Screw collar part 20 Fastening material 21 Burring part 23 Screw engaging part (female screw part)
30 Fastened material 32 Collar contact part (seat surface part)
41 Folded shape 41a Diagonal bent shape 46 Folded collar contact portion 90 Fastening portion

Claims (8)

A screw having a screw head and a screw screw part;
A fastening member having a screw engaging portion for screwing with the screw screw portion;
Sandwiched between the fastening member and the seating surface of the screw, and the object to be fastened member are fastened by the screws,
In the fastening part structure having
The screw head has a screw bristle portion protruding outward in the radial direction of the screw screw portion, the material to be fastened includes a hole through which the screw passes, and an edge portion of the hole is folded back to the screw head side. A folded portion having an elastically deformable shape, the folded portion having a first corner formed on a first surface facing the seating surface at a tip of the folded portion, and the folded portion. A second corner formed on a second surface disposed on the opposite side of the first surface at the tip of the portion, wherein the first corner is in a direction to bite into the seating surface. The fastening portion structure according to claim 1, wherein the second corner portion is in contact with the seat surface while being in contact with the screw flange portion . Fastening structure according to claim 1 wherein said second edge of the distal end of the folded portion, wherein characterized that you have been the folded portion so as not to contact with the fastening member is formed. Fastening structure according to claim 1 or 2, wherein the fastening member is characterized by being formed by thin plate-like metal plate. Wherein the fastening member includes fastening portion structure according to any one of claims 1 to 3, characterized in that it is formed by thin plate-like metal plate.   A screw having a screw head and a screw screw part, a fastening material having a screw engaging part for screwing with the screw screw part, and a seating surface of the screw and the fastening material, and being fastened by the screw. In the method of manufacturing a fastener, the screw head has a screw bristle portion protruding outward in the radial direction of the screw screw portion.
  Forming a hole through which the screw passes in the material to be fastened;
  A step of forming a folded portion that can be elastically deformed by folding the periphery of the hole of the material to be fastened to the screw head side;
  The first corner formed on the first surface facing the screw seating surface at the tip of the folded portion is brought into contact with the screw brim portion in a direction to bite into the screw seating surface, A step of screwing the screw into the screw engaging portion in a state where the second corner portion formed on the second surface disposed on the opposite side is not in contact with the seat surface;
The manufacturing method of the fastener characterized by having.   6. The method for manufacturing a fastener according to claim 5, wherein the folded portion is formed such that the second corner portion at the tip of the folded portion does not contact the material to be fastened.   The method for manufacturing a fastener according to claim 5 or 6, wherein the material to be fastened is formed of a thin metal plate.   The said fastening material is formed with the thin-plate-shaped metal plate, The manufacturing method of the fastening thing as described in any one of Claims 5-7 characterized by the above-mentioned.

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