JP2017219158A - Coupling structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coupling structure which permits a plurality of times of fastening of a tapping screw while using a prepared hole for tapping of a single inner radius.SOLUTION: A coupling structure couples a base plate 20 to a power module 10 by using a prepared hole 12 for tapping formed on the power module 10 and a tapping screw TS which is inserted to the base plate 20 and is fastened to the prepared hole 12 for tapping. Therein, as the tapping screw TS, a plurality of kinds of tapping screws TS(1), TS(2), TS(3) in which lengths of a screw part 32 to be fastened to the prepared hole 12 for tapping are shorter than a dimension Lx of a depth of the prepared hole 12 for tapping and the lengths are different from one another are prepared, and the tapping screws TS(1), TS(2), TS(3) have a dimension of such an effective length Ly that the tapping screw having relatively long length of the screw part 32 can obtain necessary fastening force for the tapping screw having relatively short length or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a two-member connection structure using a tapping screw.

Conventionally, a fastening structure is known in which a screw portion of a tapping screw inserted through a second member is fastened to a tapping hole formed in the first member, and the first member and the second member are coupled. (For example, refer to Patent Document 1).
In this prior art, the tapping hole is formed in two stages, a first hole having a small diameter on the bottom side and a second hole having a large diameter on the opening side. Then, at the time of the first coupling operation, the first tapping screw is fastened to the first small hole provided on the bottom side of the tapping hole. Thereby, the first hole is plastically deformed by the male screw of the first tapping screw to form the female screw, and both are firmly fastened.
In this operation, when a problem occurs, the first tapping screw and the second member are once removed, and when the second member is fixed again, the diameter is larger than that of the first tapping screw. A second tapping screw having a threaded portion is fastened to the large-diameter second hole on the opening side. Therefore, the second hole is newly plastically deformed by the male screw of the second tapping screw to form the female screw, and both can be firmly fastened.
As described above, in the prior art, the tapping screw and the second member can be removed once and the second member can be coupled again, though the tapping screw is plastically deformed by the tapping screw. At the same time, a strong bond was possible.

Japanese Patent Laid-Open No. 10-259810

  However, in the above-described prior art, it is necessary to form the first hole and the second hole having different inner diameters coaxially as the tapping pilot holes. In this case, since a tapping pilot hole cannot be formed unless a tool having a different diameter is used a plurality of times, compared to the case where a single inner diameter tapping pilot hole is formed with one tool, the manufacturing labor, Manufacturing time and manufacturing cost are required.

  The present invention has been made paying attention to the above-described problem, and provides a coupling structure that allows a plurality of tapping screws to be fastened even when a tapping pilot hole having a single inner diameter is used. With the goal.

The coupling structure of the present invention is a coupling structure for coupling the first member and the second member,
Several types of tapping screws with different lengths are prepared as tapping screws for fastening to the pilot holes for tapping parts.
The tapping screw has a dimension that is longer than an effective length by which a necessary fastening force can be obtained with respect to a relatively long screw part having a relatively long length. A bonded structure was adopted.

In the coupling structure of the present invention, when the tapping screw is re-fastened to the tapping pilot hole, the tapping screw having a screw portion longer than the effective length by the tapping screw fastened last time is fastened. Thereby, in the tapping pilot hole, a portion having a length longer than the effective length can be newly plastically deformed to obtain a necessary fastening force.
Therefore, it is a case where a tapping pilot hole having a single inner diameter that is easy to process is used, and a plurality of tapping screws can be fastened and a necessary fastening force can be secured. And in order to enable such re-fastening, it is not necessary to use a special pilot hole structure or to exchange a processed part for its manufacture, and the manufacturing cost and labor can be reduced.

It is sectional drawing which shows the outline of the coupling structure of Embodiment 1, Comprising: The state which fastened the thing with the shortest screw part among the tapping screws of several length is shown. It is sectional drawing which shows the outline of the coupling structure of Embodiment 1, Comprising: The state which fastened the thing with the 2nd shortest screw part among the tapping screws of several length is shown. It is a side view which shows the tapping screw used for the coupling structure of Embodiment 1, (a) shows the shortest screw part, and (b) shows the second shortest screw part. (C) shows the longest screw part. FIG. 5 is a cross-sectional view illustrating an outline of a coupling structure of a comparative example for explaining the operation of the coupling structure of the first embodiment. 6 is a cross-sectional view illustrating an outline of a coupling structure according to a second embodiment. FIG.

Hereinafter, the best mode for realizing the coupling structure and the coupling method of the present invention will be described based on the embodiments shown in the drawings.
(Embodiment 1)
First, the coupling structure of the first embodiment will be described.
1 and 2 are cross-sectional views showing an outline of a coupling structure using the tapping screw TS according to the first embodiment.
In the coupling structure of the first embodiment, an inverter driving substrate 20 as a second member is attached to a power module 10 of an in-vehicle inverter (not shown) as a first member using a tapping screw TS. , Applied to join.

  The power module 10 is provided in the main body of the above-described in-vehicle inverter (not shown), is made of resin, and has a boss portion 11 that supports the substrate 20 and a tapping bottom formed on the boss portion 11. And a hole 12. In addition, as resin which forms the power module 10, ABS (acrylonitrile butadiene styrene) resin, POM (polyacetal) resin, etc. can be used, for example.

  The board 20 is provided with a screw insertion hole 21 at a position coaxial with the tapping pilot hole 12 when the power module 10 is disposed at a predetermined coupling position.

  The tapping pilot hole 12 is a round hole having a single inner diameter (inner diameter hr) over the entire length Lx, and when the tapping screw TS is fastened, the inner periphery of the tapping pilot hole 12 is plastic. A female screw (not shown) is formed by deformation. The depth dimension Lx and the inner diameter hr of the tapping pilot hole 12 will be described later.

  The tapping screw TS includes a head portion 31 and a screw portion 32, and a male screw is formed on the outer periphery of the screw portion 32. Further, as the tapping screw TS, in the first embodiment, as shown in FIGS. 3A, 3B, and 3C, three types of tapping screws TS (1), TS having different lengths of the screw portion 32 are used. (2) and TS (3) are prepared in advance.

  In the description of the three types of tapping screws TS (1), TS (2), and TS (3), when a specific length screw is indicated, (1) (2) (3 ), And when it does not point to a specific length, it is simply written as TS. Also for the screw part 32, when it indicates a specific length, it is distinguished by adding (1), (2), and (3) after the reference numeral 32, and when the specific length is not indicated Is simply written as 32.

  Since the screw part 32 forms a female screw on the inner periphery of the tapping pilot hole 12 as described above, the outer diameter of the male screw part of the screw part 32 is the inner diameter hr of the tapping pilot hole 12. It is formed in a larger dimension.

  Next, the relationship between the length dimension Ln of the screw portion 32 of the tapping screws TS (1), TS (2), and TS (3) and the depth dimension Lx of the tapping pilot hole 12 will be described.

First, the dimension Ln of the screw part 32 will be described with reference to FIG.
The length Ln of the length of the screw portion 32 includes a dimension Lt corresponding to the thickness t (see FIG. 1) of the substrate 20, an effective length Ly for securing a necessary fastening force when fastening to the tapping pilot hole 12, and a tip. This is the total dimension of the tip invalid portion Lsv having a diameter smaller than the inner diameter hr of the tapping pilot hole 12 of the portion. In addition, even if it exists in the dimension Ln of the length of a screw part, when expressing the individual dimension of each screw part 32 (1), 32 (2), 32 (3), it is (1) ( 2) Differentiate by adding (3).

  The dimension Ln (1) of the length of the threaded portion 32 (1) of the shortest tapping screw TS (1) shown in FIG. 3A includes a dimension Lt, an effective length Ly, and a distal end invalid length Lsv. The total dimensions are used. The effective length Ly is a length set in advance to obtain a required fastening force when fastened to the tapping pilot hole 12 as described above. The effective length Ly is the required fastening force. As long as the length can be obtained.

  The dimension Ln (2) of the length of the screw portion 32 (2) of the tapping screw TS (2) shown in FIG. 3B, which is the second longest among the three types of tapping screws TS, is the length of the screw portion 32 (1). The dimension obtained by adding the effective length Ly to the dimension Ln (1). That is, as shown in FIGS. 3A and 3B, the length dimension Ln (2) of the screw portion 32 (2) is Ln (1) −Lsv + Ly + Lsv. Further, in the first embodiment, as described above, the length dimension Ln (2) of the screw portion 32 (2) is equal to the effective length Ly of the length Ln (1) of the screw portion 32 (1). However, the added value for the dimension Ln (1) may be equal to or greater than the effective length Ly. Further, the screw portion 32 (2) may be formed with a male screw as shown in the figure above the portion shown as the effective length Ly in FIG. May be.

The dimension Ln (3) of the length of the screw portion 32 (3) of the tapping screw TS (3) shown in FIG. 3 (c) which is the longest among the three types of tapping screws TS is the length of the screw portion 32 (2). The dimension is obtained by adding the effective length Ly to the dimension Ln (2). That is, as shown in FIGS. 3B and 3C, the length dimension Ln (3) of the screw portion 32 (3) is Ln (2) −Lsv + Ly + Lsv. Also in this case, the added value for the dimension Ln (2) may be equal to or greater than the effective length Ly. In addition, the screw portion 32 (3) may be formed with a male screw as shown in the figure above the portion shown as the effective length Ly in FIG. Good.
As described above, the length Ln + 1 of the (n + 1) -th screw portion from the shorter tapping screw TS is set to be Ln + 1 = Ln−Lt−Lsv + Ly × (n + 1) + Lt + Lsv.

  The depth dimension Lx of the tapping pilot hole 12 is formed to be slightly larger than the length dimension Ln (3) of the threaded portion 32 (3) of the longest tapping screw TS (3). Therefore, when the tapping screw TS (3) is fastened to the tapping pilot hole 12, the tip thereof does not reach the bottom 12a of the tapping pilot hole 12.

  Next, although the fastening method as an effect | action of Embodiment 1 is demonstrated based on drawing, a comparative example is demonstrated prior to this.

(Comparative example)
FIG. 4 illustrates a coupling structure using a tapping screw according to a comparative example.
In this comparative example, the second member 020 is fixed to the boss part 011 of the first member 010, and the boss part 011 of the first member includes a tapping pilot hole 012 having a general size. The depth dimension 0Lx of the tapping pilot hole 012 is determined by the length dimension 0Ln of the screw part 032 of the tapping screw 030 to be fastened, and the tip thereof does not contact the bottom part of the tapping pilot hole 012 when the tapping screw 030 is fastened. Dimension is formed. The dimension that the tip does not contact the bottom of the tapping pilot hole 012 is, for example, a dimension obtained by adding about 1 mm to the dimension 0Ln of the screw part 032.

  In this comparative example, for example, when the second member 020 is assembled to the first member 010, the tapping screw 030 is dropped on the second member 020 to cause a problem with the second member 020. The second member 020 is replaced with a new one. In such a manufacturing process, the tapping screw 030 once fastened is once removed and fastened again after the second member 020 is replaced.

At that time, in the case of a normal screw fastening structure, it is possible to re-fasten the screw after replacing it with a new one. However, with the tapping screw 030, the tapping screw 030 itself uses the tapping screw 030 itself at the time of fastening. 012 is plastically deformed. For this reason, at the time of re-fastening, sufficient fastening torque cannot be obtained, and the tapping pilot hole 012 cannot be reused as it is. Therefore, it is necessary to replace the boss part 011 or to recut the tapping pilot hole 012 at another part of the boss part 011. In these cases, additional processing time and cost are required.
Or although the technique of the said patent document 1 can also be used, also in this case, as mentioned above, manufacturing effort, manufacturing time, and manufacturing cost take extra.

(Fastening work in Embodiment 1)
Next, a fastening work procedure according to the fastening method of the first embodiment will be described.
<At the first conclusion>
At the time of fixing the substrate 20 for the first time, as shown in FIG. 1, the substrate 20 is coupled to the power module 10 by using the tapping screw TS (1) having the shortest screw portion 32. That is, the screw insertion hole 21 of the substrate 20 is disposed at the same position as the tapping pilot hole 12, and the screw portion 32 (1) of the tapping screw TS (1) is inserted into the screw insertion hole 21 for tapping. Fasten to the pilot hole 12.

  Thereby, the inner periphery of the tapping pilot hole 12 is plastically deformed into a female screw shape by the male screw formed on the outer periphery of the screw portion 32 of the tapping screw TS (1), and a necessary fastening force can be obtained. In this case, the tapping pilot hole 12 is plastically deformed from the opening end of the upper end to the lower position by the effective length Ly, as shown in FIG. 1, and the necessary fastening force is obtained.

<When re-engaged>
Next, the case where the fixing work is performed again will be described.
For example, in the first fixing operation of the substrate 20, if a problem such as damage to the substrate 20 occurs, the tapping screw TS (1) and the substrate 20 are once removed, and the substrate 20 is replaced with a new one. Exchange.

  When the substrate 20 is replaced, the new substrate 20 is fixed to the boss portion 11 again. At this time, a longer one than the tapping screw TS (1), for example, the tapping screw shown in FIG. TS (2) is fastened to the tapping pilot hole 12.

  In this case, the screw portion 32 (2) of the tapping screw TS (2) has an effective length further than the depth corresponding to the effective length Ly plastically deformed when the tapping screw TS (1) is fastened in the tapping pilot hole 12. Fasten to a position deeper by Ly. As a result, the tapping screw TS (2) can newly plastically deform the tapping pilot hole 12 by the effective length Ly to ensure a necessary fastening force.

<When re-signing>
When re-fastening using the tapping screw TS (2), a problem occurs, and when the substrate 20 is replaced again, it is fastened to the tapping pilot hole 12 using the tapping screw TS (3).

  In this case, the screw portion 32 (3) of the tapping screw TS (3) is further deeper by an effective length Ly than the depth Ly + Ly plastically deformed by the tapping screw TS (2) in the tapping pilot hole 12. An internal thread can be formed by plastic deformation. Therefore, a necessary fastening force can be obtained even when the tapping screw TS (3) is fastened.

  As described above, in the first embodiment, the tapping screws TS (1), TS (2), TS83) can be used for a plurality of times of fastening while using the tapping pilot holes 12 having a single inner diameter. Yes, and the necessary fastening force can be obtained each time. For re-fastening, there is no need for a special pilot hole structure or replacement of a processed part for its manufacture, which can reduce manufacturing effort, manufacturing time, and manufacturing cost.

(Effect of Embodiment 1)
The effects of the first embodiment are listed below.
1) The coupling structure of Embodiment 1 is
A tapping pilot hole 12 formed in the power module 10 as the first member;
A tapping screw TS inserted through the substrate 20 as the second member and fastened to the tapping pilot hole 12;
A coupling structure for coupling the power module 10 and the substrate 20 using
As the tapping screw TS, the length of the screw portion 32 fastened to the tapping pilot hole 12 is shorter than the depth dimension Lx of the tapping pilot hole 12, and a plurality of types of tapping screws TS (different from each other) 1), TS (2), TS (3) are prepared,
The tapping screws TS (1), TS (2), and TS (3) can obtain the required fastening force when the length of the screw portion 32 is relatively long when the screw portion 32 is relatively long. It has a dimension that is longer than the effective length Ly that can be achieved.

In the present embodiment, when the tapping screw TS is re-fastened, the tapping screw TS (2) whose screw portion 32 is longer than the tapping screw TS (1) fastened last time is fastened. As a result, the tapping pilot hole 12 can be plastically deformed to a length equal to or longer than the effective length Ly to obtain a necessary fastening force.
Therefore, even when the tapping pilot hole 12 having a single inner diameter is used, the tapping screw TS can be fastened a plurality of times, and a necessary fastening force can be secured each time. For re-fastening, there is no need for a special pilot hole structure or replacement of a processed part for its manufacture, which can reduce manufacturing effort, manufacturing time, and manufacturing cost. In addition, the tapping screw TS is different only in the length of the screw portion 32, and it is easy to use an existing general-purpose product. In this respect as well, manufacturing labor, manufacturing time, and manufacturing cost can be suppressed.

2) The coupling structure of Embodiment 1 is
Among the tapping screws TS (1), TS (2), TS (3), the shortest screw portion 32 (1) has at least a dimension Lt corresponding to the thickness t of the substrate 20, an effective length Ly, and a tip portion. A dimension Ln (1) equal to or greater than the value obtained by adding the invalid length Lsv,
The screw portions 32 (2) and 32 (3) of the other tapping screws TS (2) and TS (3) add at least an effective length Ly to those of the relatively short screw portion 32 (1). It is characterized by having the dimensions Ln (2) and Ln (3).
Therefore, the effective length Ly can be reliably ensured as the length of the screw portion 32, and reliable re-fastening is possible.

3) The coupling structure of Embodiment 1 is
The thread portions 32 (2) and 32 (3) of the other tapping screws TS (2) and TS (3) are n in the order from the shortest, the dimension corresponding to the thickness of the substrate 20 is Lt, and the effective length is When Ly and the distal end invalid length are Lsv, the length Ln + 1 of the (n + 1) -th screw portion is
Ln + 1 = Ln−Lt−Lsv + Ly × (n + 1) + Lt + Lsv.
Therefore, the necessary fastening force can be reliably obtained while minimizing the length of the screw portions 32 (2) and 32 (3). In addition, this makes it possible to expand the options of the lengths of the screw portions 32 (2) and 32 (3), and further, it is not necessary to prepare a screw having a dedicated length, so that the cost can be reduced by sharing the parts. .
In addition, the fastening force of each tapping screw TS (1), TS (2), TS (3) can be made uniform, and the coupling quality can be made uniform.
Furthermore, since the dimension Lx of the depth of the tapping pilot hole 12 can be suppressed to a necessary minimum, it is possible to secure a large number of re-fastening operations while suppressing the dimension of the power module 10.

4) The coupling method using the tapping screw of the first embodiment is as follows:
First, the screw part 32 (1) of the tapping screw TS (1) as a relatively short tapping screw is inserted into the substrate 20, and then fastened to the tapping pilot hole 12, so that the substrate 20 is attached to the power module 10. Combine and
Next, when the substrate 20 is once removed and recombined,
First, remove the tapping screw TS (1),
Next, the tapping screw TS (2) as a relatively long tapping screw is inserted into the substrate 20 to be recombined and then fastened to the tapping pilot hole 12.
Therefore, even when the tapping pilot hole 12 having a single inner diameter is used as in 1) above, it is possible to fasten the tapping screw TS a plurality of times and ensure the necessary fastening force. Therefore, a special pilot hole structure for re-fastening or a work for exchanging a processed part for the manufacture thereof is not required, and manufacturing labor, manufacturing time, and manufacturing cost can be reduced.

(Other embodiments)
Next, a coupling structure according to another embodiment will be described.
Note that in the description of other embodiments, components that are the same as those in the other embodiments are denoted by the same reference numerals as those of the present embodiment, and description thereof is omitted. Only differences from the present embodiment will be described.

(Embodiment 2)
The second embodiment is characterized in that a tapping pilot hole 212 is formed so as to penetrate the boss portion 211 of the power module 210.

Therefore, in the second embodiment, in addition to the effects 1) to 4), the following effects are obtained.
That is, in the second embodiment, since the tapping pilot hole 212 does not have a bottom portion, the vertical dimension in the figure of the power module 210 is suppressed with respect to the length of the tapping screw TS to be fastened, and the power module 210 is made compact. Can be further planned.

  As described above, the present invention has been described based on the embodiment. However, the specific configuration is not limited to this embodiment, and it does not depart from the gist of the invention according to each claim of the claims. Design changes and additions are allowed.

For example, in the embodiment, the example in which the substrate is coupled to the power module has been described, but the first member and the second member are not limited to these. That is, as long as at least the first member can be plastically deformed by a tapping screw, it can be applied to the connection of industrial equipment, home appliances, and other members in addition to the in-vehicle components.
In the embodiment, the length of the three types of screw portions is shown as the tapping screw to be prepared. However, the type of the screw length is not limited to this, and at least two types are re-fastened once. May be possible. Alternatively, the length of the screw part may be four or more, and the refastening may be performed three or more times. Furthermore, in the embodiment, an example in which the dimensional difference in the length of each tapping screw is an effective length is shown, but the present invention is not limited to this, and may be a dimensional difference longer than the effective length. In this case, the fastening force at the time of fastening can be ensured more reliably.

  Further, in the embodiment, the example in which the male screw is formed over the entire length of the screw portion is illustrated. However, if the male screw is formed at least on the distal end side that represents the effective length Ly in FIG. However, a male screw may not be formed on the east side.

  Furthermore, in the embodiment, the example in which the length Ln + 1 of the (n + 1) th screw portion is set to Ln + 1 = Ln−Lt−Lsv + Ly × (n + 1) + Lt + Lsv is shown, but Ln + 1> Ln−Lt−Lsv + Ly × (n + 1) + Lt + Lsv It is good. In this case, a higher fastening force can be reliably ensured at the time of re-fastening.

10 Power module (first member)
11 Boss portion 12 Tapping pilot hole 20 Substrate (second member)
31 Head portion 32 Threaded portion Ln (Thread portion length) dimension Lsv Tip end invalid length Lt (Substrate 20 thickness t) Dimension Lx (Tapping pilot hole depth) Dimension Ly Effective length TS Tapping screw

Claims (4)

A tapping pilot hole formed in the first member;
A tapping screw inserted through the second member and fastened to the tapping pilot hole;
A coupling structure for coupling the first member and the second member using
As the tapping screw, there are prepared a plurality of types of tapping screws in which the length of the screw portion fastened to the tapping pilot hole is shorter than the depth dimension of the tapping pilot hole, and the lengths are different from each other.
The tapping screw has a dimension that is longer than an effective length by which a necessary fastening force can be obtained with respect to a relatively long screw part having a relatively long length. Bond structure. The coupling structure according to claim 1,
Of the tapping screws, the shortest screw portion has at least a dimension equal to or greater than a value obtained by adding the thickness of the second member, the effective length, and the ineffective length of the tip.
The screw structure of another tapping screw has a size obtained by adding at least the effective length to a screw portion having a relatively short size. The coupling structure according to claim 2,
The thread portion of the other tapping screw is n + 1 when the thickness from the shortest is n, the thickness of the second member is t, the effective length is Ly, and the ineffective length is Lsv. The length Ln + 1 of
Ln + 1 ≧ Ln−t−Lsv + Ly × (n + 1) + t + Lsv It is the coupling | bonding method by the coupling | bonding structure of any one of Claims 1-3, Comprising:
First, after inserting the screw portion of a relatively short tapping screw into the second member, the second tapping screw is fastened to the tapping pilot hole, and the second member is coupled to the first member,
Next, when removing and recombining the second member,
First, remove the relatively short tapping screw,
Next, a relatively long tapping screw is inserted into the second member to be recoupled, and then fastened to the tapping pilot hole.