JPH06341418A - Snap contact member - Google Patents

Abstract

PURPOSE:To simply and surely connect a member to be connected by increasing allowable bending quantity even if a snap contact member is formed out of plastic of which allowable distortion is low and is fragile. CONSTITUTION:At an extending part from a base material 1 a nail part 3 for connecting a member to be connected is formed. At a base of the extention part 2, a cut part 4 shaped in U letter in plane view is formed and a cantilever type continuous part to which the base material 1 and the extension part 2 are continuous is formed. By using bending quantity of the part 5, the allowable bending quantity of extention part 2 can be made large.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a snap joint member which is useful when a member such as a plastic part is fitted and is engaged with a claw portion to join them.

[0002]

2. Description of the Related Art Conventionally, housings, casings, and the like of electronic equipment are formed by joining a plurality of members with screws or the like. However, in such a joining method, not only the positioning of each member but also the screw fixing work is complicated and the assembling efficiency is low.

Therefore, in recent years, various snap joining members have been proposed in order to join and join a plurality of members by a simple method of fitting. For example, JP-A-55-1
Japanese Patent No. 55602 discloses a snap button in which a head member is joined by a member having a flange for fixing to a coating and an elastic hole capable of radially expanding in diameter and having a claw portion formed at a tip end thereof. Is proposed. Also, ANTEC 1987, 912-917 (1987) and Machine Design, 80-85.
(1984) and the like propose a snap joint in which another member is engaged with a member having a claw formed at its tip.

FIG. 6 is a schematic perspective view showing a conventional snap joint member, and FIG. 7 is a schematic vertical sectional view showing a joint process by the snap joint member shown in FIG.

The snap joint member has an extending portion 42 extending from the base material 41 and a claw portion 43 formed at the tip of the extending portion 42. When joining the members to be joined with such a joining member, as shown in FIG.
When the inclined surface of the claw portion 43 and the inclined surface of the member to be joined 44 are brought into contact with each other and the member 44 to be joined is pushed in the axial direction of the extension portion 42, the member 44 to be joined is extended along with the movement thereof. The part 42 is
The claw portion 43 at the tip portion sequentially bends in the lateral direction with respect to the pushing direction, and the extension portion 42 is distorted. When the joined member 44 further moves in the axial direction, the claw portion 43 and the joined member 4
The end of 4 engages, and both are joined.

With the fitting of the member 44 to be joined, the maximum strain occurs in the base portion of the extending portion 42. This strain amount δ is
As shown in FIG. 6, the thickness of the extending portion 42 is t, and the claw portion 4 is
When the length of the extending portion 42 up to 3 is L and the amount of bending at the claw portion 43 is y, it is expressed by the following equation.

Strain amount δ = 6 × t × y / L ² In such a joint member, the thickness t of the extending portion 42 is
Is constrained by the thickness of the base material 41, the length L of the extending portion 42 is constrained by the size of the member 44 to be joined, and the bending amount y is constrained by the allowable strain amount of the extending portion 42. Therefore, when the joining member is made of a plastic material that is brittle and has a small allowable strain amount, the bending amount y is largely restricted and is often not suitable as a joining member.

The same applies to the case where the joining member is made of a plastic material reinforced by a reinforcing material. That is, plastics reinforced with reinforcing fibers such as glass fibers and carbon fibers have high strength and rigidity and are used as molding materials for many parts. However, many of these fiber reinforced plastics have large brittleness and a small allowable strain amount, and thus are not suitable as a material for snap joining. The same applies to plastic materials reinforced with organic or inorganic fillers.

In addition, in a joining member formed of a plastic material which is brittle and has a small allowable strain amount, as shown in FIG. 8, the allowable deflection amount y1 is the thickness t of the extending portion 42 and the claw portion 43. Let L0 be the length of the extended portion 42 up to and the allowable strain amount of the material be e.

[0010] Since the allowable deflection amount ^{y1 = e × Lo 2/6} / t, the amount of deformation of the extending portion 42, exceeds an allowable amount of distortion of the plastic constituting the joining member, the extending portion 42 is plastically deformed or destroyed Occurs, and snap joining becomes impossible. In particular, since the allowable bending amount y1 is often smaller than the bending amount y corresponding to the length of the step portion of the claw portion 43, the joining member formed of a plastic material which is brittle and has a small allowable strain amount is extended. It is difficult to increase the allowable bending amount of the portion 42.

On the other hand, if the joining member is made of flexible plastic, the allowable strain amount can be increased, but it is difficult to join the members to be joined securely and firmly.

[0012]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a snap joint member which has a large permissible bending amount and can be joined to a member to be joined even if it is made of plastic which is brittle and has a small allowable strain amount. Especially.

Another object of the present invention is to prevent plastic deformation and fracture even if the extension portion is deformed more than the allowable strain amount,
An object of the present invention is to provide a snap joint member that can simply and reliably join the members to be joined.

[0014]

Means for Solving the Problems As a result of intensive studies for achieving the above-mentioned object, the inventors of the present invention have found that when a cutout portion is formed around the base portion of the extension portion, the allowable bending amount of the extension portion can be increased. Then, the present invention was completed.

That is, the snap joint member of the present invention is
An extension part extending from a base material, and a plastic joining member composed of a claw portion formed at an end portion of the extension part, of the base material, of a base part of the extension part. A cutout portion is formed around the periphery with a part left.

[0016]

According to the snap joint member having the above-mentioned structure, the base material and the extending portion are continuously provided in correspondence with the non-cutting portion by the cutting portion formed around the base of the extending portion of the base material. It is possible to form a continuous connection part. Therefore, even if it is made of rigid and brittle plastic, the bending amount of the extending portion can be increased by utilizing the bending of the connecting portion.

[0017]

Embodiments of the present invention will now be described in more detail with reference to the accompanying drawings.

FIG. 1 is a schematic perspective view showing an embodiment of the snap joint member of the present invention.

This joining member is formed on a flat plate-shaped base material 1, an extension portion 2 having a rectangular cross section extending from this base material, and a tip end portion of the extension portion 2, and one side surface is directed downward. It is configured with a claw portion 3 having an inclined surface 3a. The joining member is formed by integral molding of plastic having high rigidity.

Then, around the base of the extending portion 2,
The cutout portion 4 is formed by leaving a part of the base material. That is, the planar U-shaped slit-shaped cutting portion 4 is formed, leaving the portion of the base material 1 corresponding to the side opposite to the inclined surface 3a side (projection portion side) of the claw portion 3, and is not cut. The portion is formed as a cantilever-shaped continuous portion 5 that connects the extending portion 2 and the base material 1.

With such a joining member, as shown in FIG. 2, the amount of bending of the extending portion 2 can be increased. That is, the allowable deflection amount y2 of the extending portion 2 of the joining member is t, the thickness of the extending portion 2, the length of the extending portion 12 from the base material 1 to the claw portion 3 is L0, and the allowable strain amount of the material. Where e is the bending angle at the base of the extending portion 2 and is θ, it is simply expressed by the following equation.

Allowable deflection amount y ² = e × Lo 2/6 / t + θL 0 = y 1 + θL 0 In the above formula, the deflection angle θ changes depending on the size and shape of the cantilever-shaped continuous portion 5. Therefore, even if the joining member is formed of plastic having a small allowable strain amount, the bending angle θ can be increased by adjusting the size and shape of the cantilever-shaped continuous connection portion 5, particularly the length of the continuous connection portion 5. , The permissible deflection amount y2 of the extending portion 2 is the permissible deflection amount y1 of the joining member that does not form the cut portion.
Can be bigger than

Moreover, since the cutout portion 4 is formed on the side opposite to the joining site of the members to be joined, that is, on the side opposite to the projecting side of the claw portion 3, fitting and mounting of the members to be joined, etc. Is not damaged.

The base material is not limited to the flat plate shape, and may be, for example, a curved plate shape or a block shape depending on the type of the joining member. The cross-sectional shape of the extending portion extending from the base material is not particularly limited, and may be a polygonal shape such as a circular cross section, an elliptical cross section, or a triangular cross section, but it is usually a rectangular cross section, particularly a rectangular cross section. In many cases. The extension may be joined to the base, and may be joined with an adhesive or the like as necessary. In addition, the extending portion can be formed at a plurality of locations on the base material so as to correspond to the members to be joined. Usually, the base material and the extension portion are often integrally formed by a method such as injection molding.

The claw portion can be formed at a proper position on the end portion of the extending portion, but it is usually formed on the tip portion. The claw portion is not limited to a flat inclined surface and may have a curved inclined portion for guiding the member to be joined. Further, the claw portions may be formed at both end portions of the extension portion, or may be formed in an umbrella shape over the entire circumference of the end portion of the extension portion. Furthermore, the cross-sectional shape of the claw is
The shape is not limited to the right triangle having the lower end surface extending in the direction perpendicular to the extending portion, and may be a shape capable of joining the joining portions of the joined members, for example, a hook shape or the like.

The excision portion may be formed around the base portion of the extending portion with a part of the base material left over, but a cantilever connecting the base material and the base portion of the extending portion in series. In many cases, a cutout portion forming a beam-shaped continuous portion is formed. That is, the cutout portion forms a tongue-shaped continuous portion that extends from the base material and that is continuous with the extended portion. Usually, the cutout portion often forms a cantilever-shaped continuous portion extending to the protruding side (inclined surface side) of the claw portion or the side opposite to the protruding side of the claw portion.

The cut-out portion can be formed at a plurality of locations on the base material, and a continuous portion extending radially or in parallel from the base portion of the extending portion may be formed.

The shape of the cut portion need not be a U-shaped slit, and can be appropriately selected as long as a cantilever-shaped continuous portion is formed. FIG. 3 is a schematic perspective view showing another embodiment of the joining member of the present invention.

In the example shown in FIG. 3, the extending portion 12 extending from the base material 11 is provided with the claw portion 13 as described above. Further, the base material 11 has a planar U-shaped peripheral portion on the base side of the extending portion 12, and a slit-shaped cutout portion 14 which is narrowed on the side opposite to the inclined surface of the claw portion 13 is formed. The cantilever-shaped continuous portion 15 is formed.

In such a joining member, the amount of bending of the extending portion 12 can be increased by the narrow width cantilever-like connecting portion 15.

FIG. 4 is a schematic perspective view showing another embodiment of the joining member of the present invention. In this example, a curved C-shaped cutout portion 24 is formed on the base material 21 around the base portion of the extension portion 22 having the claw portion 23, and the base portion of the extension portion 22 and the base material 21 are separated from each other. The cantilever-shaped connecting portions 25 are connected continuously.

FIG. 5 is a schematic perspective view showing another joining member of the present invention. In this example, the cutout portion is formed at the opposite site of the base material, unlike the above-described embodiment. That is,
A slit-shaped cutout portion 34 and a cantilever-shaped continuous portion 35 are formed on a protruding side (a side where an inclined surface is formed) of the claw portion 33 of the extension portion 32 of the base material 31. ing. Even with such a joining member, the amount of bending of the extending portion 32 can be increased by the cantilever-shaped continuous portion 35.

When the strength of the connecting portion is small, such as a narrow connecting portion, the connecting portion, the corner portion between the extending portion and the extending portion, and the connecting portion and the base material are connected. Reinforcing ribs may be formed at appropriate places such as both connecting regions, and the base of the tongue-shaped continuous portion extending from the base material may be wide.

The joining member may be formed of a suitable plastic material, for example, a polymer having a high toughness such as polyethylene or polypropylene. In the present invention, a preferable material is usually one having a small allowable strain amount and a brittleness. Includes plastic materials that are often large and have high mechanical strength. Examples of the plastic material include polystyrene, styrene-styrene copolymers such as styrene-butadiene copolymers, acrylonitrile-styrene copolymers, acrylonitrile-phthaldiene-styrene copolymers, acrylic polymers such as polymethylmethacrylate, and polychlorides. Examples include vinyl-based polymers such as vinyl, molding plastics such as polycarbonate, polyester, polyamide, polyacetal, and engineering plastics; reinforced plastics obtained by reinforcing these plastics with reinforcing materials such as glass fibers and carbon fibers.

The snap joint member of the present invention can be used for assembling various parts, for example, assembling the housing and casing of electronic equipment.

[0036]

EFFECTS OF THE INVENTION Since the snap joint member of the present invention can increase the bending amount of the extending portion by the cutout portion, even if it is made of brittle plastic having a small allowable strain amount, the allowable bending amount is large, and the joined member The members can be joined.

Further, by adjusting the size and shape of the continuous portion, it is possible to adjust the allowable bending amount of the extending portion, and even if the extending portion is largely deformed, plastic deformation and destruction can be prevented, which is simple and reliable. The members to be joined can be joined together.

[0038]

[Experimental Example] The present invention will be described in more detail based on an experimental example.

Comparative Experimental Example Glass Fiber Reinforced Acrylonitrile-Butadiene-Styrene Copolymer (ABS Resin) Containing 30% by Weight of Glass Fiber
Was injection molded to form a snap joint member having the shape shown in FIG. The dimension of the snap joint member is the length L = L0 = 20 m of the extension portion 42 from the base material 41 to the claw portion 43.
m, the width W of the extending portion 42 = 9 mm, the thickness t of the extending portion 42 =
1.8 mm and y = y0 = 1.5 mm.

Experimental Example A snap joint member having the shape shown in FIG. 1 was molded in the same manner as in the comparative experimental example. The dimensions of the snap joint members are
Length L0 of the extending portion 2 from the base material 1 to the claw portion 3 = 20 m
m, the width W of the extension 2 = 9 mm, the thickness t of the extension 2 = 1.
8 mm, y = y0 = 1.5 mm, length L1 of the connecting portion 5 =
It is 10 mm.

Then, a load is applied to the inclined surface of the claw portion of the matching member obtained in the comparative experimental example and the experimental example to bend the extending portion, and the amount of bending (allowance) in which the deformation is recovered even if the load is released. The amount of flexure), the load at which the extension portion breaks, and the amount of flexure at break were measured, and the results shown in the table were obtained.

[0042]

[Table 1] As is apparent from the table, the snap joint member of the comparative experimental example has a required bending amount of 1.5 mm, but has an allowable bending amount of 1.1 mm, and the load required for breaking and the bending amount at the time of breaking Is also small. On the other hand, the snap joint member of the experimental example has a permissible deflection amount of 2.3 mm, which is twice or more that of the snap joint member of the comparative experiment example, and the load required for fracture and the deflection amount at the time of fracture are also large.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing an embodiment of a snap joint member of the present invention.

FIG. 2 is a schematic view showing a deformed state of the joining member shown in FIG.

FIG. 3 is a schematic perspective view showing another embodiment of the joining member of the present invention.

FIG. 4 is a schematic perspective view showing an embodiment of still another joining member of the present invention.

FIG. 5 is a schematic perspective view showing another joining member of the present invention.

FIG. 6 is a schematic perspective view showing a conventional snap joint member.

7 is a schematic vertical sectional view showing a joining process by the joining member shown in FIG.

8 is a schematic view showing a deformed state of the joining member shown in FIG.

[Explanation of symbols]

 1, 11, 21, 31, ... Base material 2, 12, 22, 32 ... Extending portion 3, 13, 23, 33 ... Claw portion 4, 14, 24, 34 ... Cutting portion 5, 15, 25, 35 ... Facility

Claims (4)

[Claims] 1. A plastic joining member comprising an extension portion extending from a base material and a claw portion formed at an end portion of the extension portion, wherein the extension portion of the base material is provided. A snap joint member in which a cutout portion is formed around a base portion of the portion with a part left. 2. The snap joint member according to claim 1, wherein the cutout portion forms a cantilever-shaped continuous portion that continuously connects the base material and the base portion of the extending portion. 3. The snap joint member according to claim 2, wherein a cantilever-shaped continuous portion extending to the protruding side of the claw portion or the side opposite to the protruding side of the claw portion is formed. 4. The snap joint member according to claim 1, wherein the cutout portion is formed in a U shape or a C shape.