JPH10286726A - Structure of press fitting member, and press fitting control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To press-fit one member to the other member without causing inclination of one member to a press fit part having an interference formed on the other member and at favorable precision. SOLUTION: A flange 5 is formed at one end of a nut 1 to protruded outward in a diametric direction along the whole circumference, and a recessed part 6 is formed around a surface opening in a hole 3 in a resin product 2. A horn 10a is applied to the nut 1, and it is lowered to apply pressure while ultrasonic vibration is applied, so the nut 1 is press-fitted while fusing and plasticizing the periphery of the hole 3. By final application of the flange 5 provided on the nut 1 to the recessed part 6 along the whole circumference, it is face-to-face matched with the recessed part 6, and by correcting an attitude of the nut 1, it is positioned to the resin product 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a press-fitting member and a press-fitting control method, and more particularly, to a press-fitting portion formed on a first member having an interference and a press-fitting portion formed on a second member. The present invention relates to a structure of a press-fitting member for fitting a first member into a press-fitting portion of a second member and a press-fitting control method.

[0002]

2. Description of the Related Art For example, as shown in FIG. 6, a rigid member 31 such as a metal nut has an interference with the nut 31 of a product made of synthetic resin (referred to as a resin product 32). When press-fitting into the hole 33 formed smaller than the outer peripheral shape of the nut 31, the nut 31 is placed on the hole 33 with its axis aligned, and the horn 10 a of the ultrasonic oscillator 10 is brought into contact with the nut 31. The horn 10a is lowered by driving the motor 11 (see FIG. 1) while applying ultrasonic vibration to apply pressure. Ultrasonic vibration is applied to the nut 31 to generate frictional heat, and as shown by the symbol m in FIG. 6, the periphery of the hole 33 of the resin product 32 is melt-plasticized. The nut 31 is press-fitted so as to be fitted. in this way,
When the nut 31 is press-fitted into the resin product 32, in particular, since a bolt (not shown) is screwed into the nut 31 press-fitted in a subsequent step, the positional accuracy of the nut 31 after press-fitting with respect to the resin product 2 is increased. Is required.

[0003] Conventional control for positioning the nut 31 to be press-fitted, that is, control for completing and stopping press-fitting, includes a driving amount of the motor 11 for applying pressure, that is, a moving amount of the horn 10a. Detect and Horn 1
In some cases, the drive of the motor 11 and the oscillation of the ultrasonic oscillator 10 are stopped when 0a has advanced a certain distance to complete the press-fitting (distance control). As another control, the amount of energy of the motor 11 when the horn 10a is moved to apply pressure is detected, and when the energy reaches a certain level, the driving of the motor 11 and the oscillation of the ultrasonic oscillator 10 are performed. Was stopped to complete the press-fitting (referred to as energy control). As still another control, a change in the power (power) of the motor 11 when the horn 10a is moved to apply pressure is monitored. There is a device that stops the oscillation of the ultrasonic oscillator 10 and completes the press-fitting (referred to as peak power control).

[0004]

However, in any of the above-described conventional techniques, the resin product 32 is distorted due to insufficient rigidity, and the nut 31 is displaced from the hole 33, as shown in FIG. There has been a problem that it is press-fitted so as not to be parallel and inclined with respect to the surface of the resin product 32. In the case of the distance control, when the press-fitting is completed when the horn 10a advances a predetermined distance, the hole 33 moves from a predetermined position in the press-fitting direction due to distortion of the resin product 32. There is a problem that the amount of press-fit does not reach a predetermined amount. Further, even if the oscillation is stopped when the horn 10a has advanced a predetermined distance, the oscillation does not stop immediately, so that the nut 31 is not positioned at a predetermined position with respect to the hole 33. In the case of energy control, the interference varies depending on the variation in the diameter of the hole formed in the resin product 32, so that a difference occurs in the energy amount of the motor 11 when the horn 10a is moved and pressed. There is a problem that the positional accuracy of the press-fitting of the nut 31 into the hole 33 varies. further,
In the case of the peak power control, simply monitoring the power of the motor 11 cannot identify the cause of the peak of the power, and the point at which the peak appears differs due to the amount of distortion depending on the resin product. As in the case of the control, there is a problem that the accuracy of the press-fitting position of the nut 31 into the hole 33 varies.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problem, and a press-fitting method which can press-fit one member into a press-fitting portion having an interference formed in the other member with good positional accuracy. An object of the present invention is to provide a structure of a member and a press-fit control method thereof.

[0006]

According to the first aspect of the present invention, there is provided a press-fitting member having a structure for press-fitting a first member into a press-fitting portion formed in a second member. The structure is characterized in that at least one of the members has a surface matching portion.

According to a second aspect of the present invention, in order to achieve the above object, the first member is pressed into contact with a press-fit portion formed in the second member by applying pressure. Wherein the reaction force when pressure is applied is detected, and press-fitting is stopped based on the detected reaction force.

In the invention according to claim 1, the first member is
When press-fitting into the press-fitting portion formed in the second member, the first member is positioned with respect to the second member while the surface mating portion abuts and the press-fitting of the first member is prevented. , Posture is corrected.

In the invention according to claim 2, when a pressure is applied by bringing the first member into contact with the press-fitting portion formed in the second member, the reaction force is monitored. When the reaction force of a predetermined value or more rapidly increases as the pressure is applied, the press-fitting is stopped.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an embodiment of the structure of the press-fitting member according to the present invention will be described in detail with reference to FIG.
In the drawings, the same reference numerals denote the same or corresponding parts.
In this embodiment, the first member is a metal nut 1, and the second member having a hole 3 as a press-fitting portion into which the nut is press-fitted is a resin product 2 depending on the case. Although described, the present invention is not limited to this, and it is needless to say that the present invention can be applied to other press-fitting members.

The structure of the press-fitting member according to the present invention is roughly the structure of the nut 1 or the resin product 2 when the nut 1 is press-fitted into the hole 3 formed in the resin product 2. At least one of them has a surface matching portion. In this embodiment, the face mating portion is formed at one end of the nut 1 so as to protrude radially outward over the entire circumference, and around the surface opening of the resin product 2 in the hole 3. And the recess 6 formed.

The resin product 2 is made of a material that becomes temporarily plastic due to frictional heat or the like. The formed hole 3 has an outer periphery of the nut 1 so that the nut 3 has an interference. It is formed slightly smaller than the shape. The concave portion 6 of the resin product 2 is formed so that the flange 5 abuts over the entire circumference when the nut 1 is press-fitted, and forms substantially the same surface as the surface of the resin product 2. The flange 5 as a mating portion provided on the nut 1 has a rigidity so as not to be deformed when pressed into the hole 3 of the resin product 2 and brought into contact with the concave portion 6. Therefore, the present invention is not limited to this embodiment as long as it has such rigidity, and may have a shape other than the flange 5 that protrudes radially outward. Further, when the collar 5 may protrude from the surface of the resin product 2, it is not necessary to provide the concave portion 6.

As shown in FIG. 1, a press-fitting device for press-fitting the nut 1 thus constructed into the hole 3 of the resin product 2 includes an ultrasonic oscillator 10 for applying ultrasonic vibration to the nut 1, And a motor 11 for applying pressure to the nut 1. The ultrasonic oscillation device 10 has a horn 10a that comes into contact with the nut 1, and in this embodiment, is supported so as to be able to move up and down. The motor 11 moves the ultrasonic oscillation device 10 up and down.
Is pressed into the hole 3 of the resin product 2 by pressing the horn 10a of the ultrasonic oscillator 10 at a predetermined pressure. The ultrasonic oscillator 10 or the motor 11 is provided with a reaction force detecting means (not shown) such as a sensor for detecting a reaction force when pressure is applied to the nut 1. In addition,
In this embodiment, the moving direction of the horn 10a,
That is, the case where the press-fitting direction is the vertical direction has been described, but the present invention is not limited to this, and can be applied to, for example, the case where the press-fitting is performed in the horizontal direction.

Next, an embodiment of the press-fitting control method according to the present invention will be described in the case where the nut 1 is press-fitted into the hole 3 of the resin product 2 using the press-fitting device and the press-fitting member configured as described above. This will be described with reference to FIGS. The press-fitting control method according to the present invention is a control method for press-fitting by applying pressure by bringing the nut 1 into contact with the hole 3 formed in the resin product 2. The fitting portions 5 and 6 are provided, the reaction force when pressure is applied is detected, and the press-fitting is stopped based on a sudden increase in the reaction force due to the contact of the surface fitting portions 5 and 6 due to the press-fitting.

First, the nut 1 is aligned with the hole 3 formed in the resin product 2 so that the end of the nut 1 opposite to the one end where the collar 5 is provided abuts on the resin product. Then, the motor 11 is driven to lower the horn 10a of the ultrasonic oscillator 10, and as shown in FIG. 2, the horn 10a is provided with the collar 5 of the nut 1 as shown in FIG. Make contact with the edge. At this time, since the hole 3 of the resin product 2 is formed slightly smaller than the outer peripheral shape of the nut 1 so as to have an interference, the nut 1 is formed around the opening of the hole 3 of the resin product 2. Is in contact with At this time, the horn 10a of the ultrasonic oscillator 10 causes, for example, the oscillation frequency 2 in the direction indicated by the arrow S in FIG.
Friction heat is generated by the ultrasonic vibration of 0 kHz and the output of 3 kW acting on the nut 1, and the resin product 2 in contact with the nut 1 is melted and plasticized, as shown by the symbol M in FIG. 2. It will be. Then, as the horn 10a of the ultrasonic oscillator 10 is lowered by driving the motor 11, the nut 1 subjected to the ultrasonic vibration melts and plasticizes the periphery of the hole 3 of the resin product 2 by frictional heat. While being pressed into the hole 3. The reaction force at the time of press-fitting the nut 1 at this time is detected by a reaction force detecting means provided on the ultrasonic oscillator 10 or the motor 11.

When the nut 1 is press-fitted, as shown in FIG. 3, the rigidity of the resin product 2 is low, so that the axial center NC of the nut 1 is inclined with respect to the center axis HC of the hole 3. Often done. However, in the present invention, the periphery of the hole 3 is pressed by the drive of the motor 11 in a state in which the periphery of the hole 3 is plasticized by applying ultrasonic vibration. Therefore, as shown in FIG. 5 comes into contact with the unplasticized concave portion 6 of the resin product 2 over the entire circumference, so that the two become parallel, that is, they are surface-matched. Therefore, the nut 1 has a hole 3
The posture is corrected so as to be parallel to the central axis HC of the hole 3 from the state of being press-fitted so as to be inclined with respect to the central axis HC of the hole 3.

As shown in FIG. 5, the reaction force detected when the nut is press-fitted by the reaction force detecting means is such that the reaction force is not detected as the horn 10a of the ultrasonic oscillator 10 is lowered (1). From the contact of the horn 10a with the nut 1 (at the start of press-fitting, A in FIG. 5), and the rate of change of the increase in reaction force is reduced by plasticizing the periphery of the hole 3 (2). When the collar 5 is brought into contact with the unplasticized concave portion 6 over the entire circumference (B in FIG. 5) and the posture is corrected, it rapidly increases (3). In the present invention, when a sharp increase is detected from the value of the predetermined reaction force, control is performed so that the motor 11 drives the horn 10a to move down and the ultrasonic oscillation device 10 stops the press-fitting. The motor 11 slightly lowers the horn 10a due to its inertia even after the stop signal is output. Therefore, the nut 1 is pressed to maintain the pressure, and the nut 1 is positioned with respect to the resin product 2 in this state. While maintaining this state for a predetermined time, the periphery of the plasticized hole 3 of the resin product 2 is hardened. Then, the motor 11 is driven to raise the horn 10a, and the resin product 2 in which the nut 1 is press-fitted is carried out. Move on to the next press-fitting process.

[0018]

According to the first aspect of the present invention, the press-fitting member which can press-fit the first member with good positional accuracy without inclining the first member to the press-fitting portion having the interference formed in the second member. Structure can be provided.

According to the second aspect of the present invention, there is provided a press-fitting control method capable of press-fitting the first member with good positional accuracy without inclining the first member into the press-fitting portion having the interference formed in the second member. Can be provided.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of a press-fitting member and a press-fitting device used for press-fitting the same according to the present invention.

FIG. 2 is an enlarged view showing a state in which a horn of an ultrasonic oscillation device is lowered by driving a motor and is brought into contact with a nut.

FIG. 3 is an enlarged view showing a state in which ultrasonic vibration is applied to a nut to apply pressure while plasticizing the periphery of a hole, and the nut is press-fitted in an inclined state due to distortion of a resin product.

FIG. 4 is an enlarged view showing a state in which the collar is brought into contact with the concave portion over the entire circumference so as to be surface-matched and the posture of the nut is corrected.

FIG. 5 is a graph illustrating a relationship between a reaction force detected by a reaction force detection unit when a nut is press-fitted, a lowering of a horn, and a lapse of time.

FIG. 6 is a front view of a conventional general press-fitting member and a press-fitting device used for the press-fitting.

FIG. 7 is an enlarged view showing a state in which ultrasonic vibration is applied to a conventional nut to apply pressure while plasticizing the periphery of a hole, and the nut is press-fitted in an inclined state due to distortion of a resin product.

[Description of sign]

 DESCRIPTION OF SYMBOLS 1 Nut (1st member) 2 Resin product (2nd member) 3 Hole (press-fitting part) 5 Collar (face mating part) 6 Depressed part (face mating part) A Pressing start time B Time when reaction force sharply increased

Claims (2)

[Claims] 1. A press-fitting structure in which a first member is press-fitted into a press-fitting portion formed in a second member, wherein at least one of the members has a surface mating portion formed therein. The structure of the member. 2. A control method for press-fitting by applying pressure by abutting a press-fit portion formed on a first member and a second member, and detecting a reaction force when the pressure is applied. And press-fitting is stopped based on the detected reaction force.