JP6790736B2 - Resin cap manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing a resin cap in which a metal insert nut is embedded in a synthetic resin .

There is a wheel bearing device equipped with a rotation speed detection device in a rolling bearing (hub bearing) for supporting the wheel of an automobile. In such a wheel bearing device, the north and south poles are alternately alternated in the circumferential direction at regular intervals. The arranged magnetic encoders are attached to the inner ring at one end in the axial direction of the bearing, and a magnetic sensor for detecting the rotation of the magnetic encoder facing the magnetic pole of the magnetic encoder is attached to the outer ring side of the bearing. (See, for example, Patent Documents 1 and 2).
In Patent Documents 1 and 2, a sensor cap (resin cap) having a sensor holder for holding the magnetic sensor is attached to an outer ring at one end in the axial direction of the bearing, and is attached to a synthetic resin main body of the sensor cap. An insert nut is embedded, and the sensor is fixed to the sensor cap by using the female screw of the insert nut.
Here, Patent Document 1 uses an insert nut in which a female screw is formed over the entire length on the inner surface of the side wall forming the through hole in the axial direction, and Patent Document 2 uses a bag nut type in which the entire body is formed in a bag shape. An insert nut is used.

Further, there is a hydraulic control valve attached to a master unit of a hydraulic device to adjust the flow rate of hydraulic oil discharged from a pump provided in the master unit (see, for example, Patent Document 3).
In Patent Document 3, a protective cap (resin cap) for closing the opening of the case provided in the hydraulic control valve is provided, and an insert nut and an insert washer are embedded in the synthetic resin main body of the protective cap. The protective cap is fixed to the base of the hydraulic control valve by utilizing the female screw of the insert nut.
Here, Patent Document 3 uses an insert nut and an insert washer in which a female screw is formed over the entire length on the inner surface of the side wall forming the through hole in the axial direction.

The insert nut is integrated with the synthetic resin by injection molding while being fixed to the injection molding die, and the female screw (thread portion) is exposed while being embedded in the synthetic resin.

Japanese Unexamined Patent Publication No. 2013-155881 Japanese Unexamined Patent Publication No. 2006-099889 Japanese Unexamined Patent Publication No. 2011-161757

Wheel bearing devices such as Patent Documents 1 and 2 are required to be miniaturized, and in order to meet such needs, it is necessary to reduce the thickness of the resin portion in which the insert nut is embedded in the sensor cap. That is, it is necessary to shorten the length of the insert nut as much as possible while ensuring the required length of the effective threaded portion of the insert nut.

Here, an insert nut in which a female screw is formed over the entire length on the inner surface of the side wall forming an axial through hole as in Patent Document 1 is used as an insert product, and the insert nut is externally fitted to a support pin of an injection molding mold. When the sensor cap is injection-molded in this state, the molten resin injected into the mold penetrates into the insert nut along the spiral thread of the female screw of the insert nut due to the pressure, and solidifies in that state. To do.

When an insert nut in which a female screw is formed over the entire length is used on the inner surface of the side wall forming the through hole in the axial direction, the distance (axial length) for the molten resin to penetrate into the insert nut during injection molding is, for example, about 3 mm. Become. In that case, the length of the effective threaded portion of the insert nut is shortened by about 3 mm.
Further, the distance at which the molten resin penetrates into the insert nut during injection molding varies widely during mass production.

Therefore, in consideration of large variations during mass production, it is necessary to allow a margin for a large decrease in the length of the effective threaded portion of the insert nut.
That is, even when the length of the effective screw portion of the insert nut is reduced most during mass production, the insert nut is lengthened in order to secure the required length of the effective screw portion to which the mounting screw to be used can be screwed. There is a need. If this is not done, when mounting the sensor on the sensor cap at the manufacturing site, there is a risk that the mounting screw will be screwed only halfway to the insert nut, that is, the sensor cannot be mounted. ..

As described above, in the insert nut in which the female screw is formed over the entire length on the inner surface of the side wall forming the through hole in the axial direction, the distance that the molten resin penetrates into the insert nut during injection molding is large, and the distance varies during mass production. The length of the insert nut cannot be shortened because it needs to be taken into consideration. Therefore, it is not possible to meet the need for miniaturization of reducing the thickness of the resin portion in which the insert nut is embedded in the sensor cap.

A bag nut type insert nut, which is entirely formed in a bag shape as in Patent Document 2, is used as an insert product, and the sensor cap is injection molded with the insert nut externally fitted to a support pin of an injection molding mold. In this case, the molten resin does not enter the insert nut.
However, since the bag nut type insert nut as in Patent Document 2 has a larger overall length than the insert nut in which the female screw is formed over the entire length, the thickness of the resin portion in which the insert nut is embedded cannot be reduced. I can't respond to.

Further, in the configuration in which the insert washer is used in addition to the insert nut in which the female screw is formed over the entire length on the inner surface of the side wall forming the through hole in the axial direction as in Patent Document 3, the number of parts is increased and injection molding is performed. Since it takes time and effort, the manufacturing cost increases.

Therefore, what the present invention seeks to solve in view of the above situation is to meet the need for miniaturization of reducing the thickness of the resin portion in which the insert nut is embedded in the resin cap. In order to realize this, an object of the present invention is to obtain a structure capable of shortening the length of the insert nut as much as possible while ensuring the required length of the effective threaded portion of the insert nut having a through hole in the axial direction. is there.

The method for manufacturing a resin cap according to the present invention is to solve the above-mentioned problems.
A method for manufacturing a resin cap in which a metal insert nut is embedded in a synthetic resin.
The resin cap is a sensor cap having a sensor holder portion fixed to the outer ring of the bearing and holding the sensor in a wheel bearing device provided with a sensor for detecting the rotation of an encoder fixed to the inner ring of the bearing. And
The insert nut is
One of both ends in the axial direction of the through hole in the axial direction is used as the end on the pin insertion side into which the support pin of the injection molding die is inserted.
In the through hole, the screw portion into which a bolt can be screwed from the end on the pin insertion side is formed.
The other end of the axial end of the through hole has a non-threaded portion that does not form the threaded portion.
The inner peripheral surface of the non-threaded portion is a pilot hole to be drilled before forming the threaded portion.
The injection mold is opened, the insert nut is set in the support pin so that the support pin of the mold is inserted into the through hole from the pin insertion side end of the insert nut, and the insert nut is set. The step of fitting only the non-threaded portion of the above to the tip of the support pin, and
A step of filling the molten resin material into the mold with the mold closed and the mold tightened.
After cooling and solidifying the molten resin material, the mold is opened and the resin cap, which is a molded product, is taken out.
Only including,
The axial length of the non-threaded portion of the insert nut is 0.5 mm or more and 2 mm or less.
The fitting gap between the inner peripheral surface of the non-threaded portion of the insert nut and the tip end portion of the outer peripheral surface of the support pin is 0.01 to 0.15 mm in diameter (claim 1 ).

According to such a manufacturing method, when an insert nut having a non-threaded portion having the shape is used and the insert nut is set on a support pin of a mold, the non-threaded portion of the insert nut is a support pin. Fits on the tip.
Therefore, when the mold is closed, the mold is tightened, and the mold is filled with the molten resin material, the inner peripheral surface of the non-threaded portion of the insert nut and the tip portion of the outer peripheral surface of the support pin By setting the fitting gap to a range where the resin does not wrap around according to the fluidity of the resin material used, the non-threaded portion without spiral threads is injected into the mold. Since it has the effect of blocking the intrusion of the molten resin into the insert nut, it is possible to suppress the intrusion of the molten resin into the insert nut.
In addition, the distance (axial length) that the molten resin penetrates into the insert nut is greater than in the case of using an insert nut in which a female screw is formed over the entire length on the inner surface of the side wall that forms the through hole in the axial direction. There is no big variation.
Therefore, the length of the insert nut can be shortened as much as possible while ensuring the required length of the effective threaded portion of the insert nut. Therefore, the thickness of the resin portion in which the insert nut is embedded in the resin cap molded by this manufacturing method. It is possible to meet the need for miniaturization to reduce the number of products. As a result, the sensor cap, which is the resin cap, can be miniaturized, which makes it suitable as a method for manufacturing a sensor cap used for a wheel bearing device, which is required to be miniaturized.
Furthermore, by setting the axial length of the non-threaded portion of the insert nut to 0.5 mm or more and 2 mm or less, the total length of the insert nut is provided while having the effect of suppressing the intrusion of the molten resin into the insert nut. Can be relatively short.
Further, by setting the fitting gap between the inner peripheral surface of the non-threaded portion of the insert nut and the tip end portion of the outer peripheral surface of the support pin to a diameter of 0.01 to 0.15 mm, the insert nut is said to have a diameter of 0.01 to 0.15 mm. The resin does not wrap around in the structure in which only the non-threaded portion is fitted to the tip portion of the support pin.

In addition, the method for manufacturing a resin cap according to the present invention is to solve the above-mentioned problems.
A method for manufacturing a resin cap in which a metal insert nut is embedded in a synthetic resin.
The resin cap is a sensor cap having a sensor holder portion fixed to the outer ring of the bearing and holding the sensor in a wheel bearing device provided with a sensor for detecting the rotation of an encoder fixed to the inner ring of the bearing. And
The insert nut is
One of both ends in the axial direction of the through hole in the axial direction is used as the end on the pin insertion side into which the support pin of the injection molding die is inserted.
In the through hole, the screw portion into which a bolt can be screwed from the end on the pin insertion side is formed.
The other end of the axial end of the through hole has a non-threaded portion that does not form the threaded portion.
The inner peripheral surface of the non-threaded portion has a tapered surface whose diameter decreases as the distance from the pin insertion side end portion increases.
The injection molding die is opened, and a support pin having a tapered surface formed at the tip of the mold in contact with the tapered surface of the insert nut is inserted into the through hole from the pin insertion side end of the insert nut. A step of setting the insert nut on the support pin so that only the tapered surface of the insert nut is in contact with the tapered surface of the support pin.
A step of filling the molten resin material into the mold with the mold closed and the mold tightened.
After cooling and solidifying the molten resin material, the mold is opened and the resin cap, which is a molded product, is taken out.
Only including,
The axial length of the non-threaded portion of the insert nut is 0.5 mm or more and 2 mm or less.
The fitting gap between the inner peripheral surface of the non-threaded portion of the insert nut and the tip end portion of the outer peripheral surface of the support pin is 0.01 to 0.15 mm in diameter (claim 2 ).

According to such a manufacturing method, when the insert nut is set on the support pin, the tapered surface of the insert nut is in contact with the tapered surface of the support pin, so the mold is closed, the mold is tightened, and the mold is placed inside the mold. When the step of filling the molten resin material is performed, it is possible to prevent the molten resin from invading the threaded portion of the insert nut.
Further, by setting the axial length of the non-threaded portion of the insert nut to 0.5 mm or more and 2 mm or less, the total length of the insert nut can be increased while having the effect of suppressing the intrusion of the molten resin into the insert nut. Can be relatively short.
Further, by setting the fitting gap between the inner peripheral surface of the non-threaded portion of the insert nut and the tip end portion of the outer peripheral surface of the support pin to a diameter of 0.01 to 0.15 mm, the insert nut is said to have a diameter of 0.01 to 0.15 mm. In a structure in which only the tapered surface is in contact with the tapered surface of the support pin, the resin does not wrap around.

Further, the method for manufacturing a resin cap according to the present invention is to solve the above-mentioned problems.
A method for manufacturing a resin cap in which a metal insert nut is embedded in a synthetic resin.
The resin cap is a sensor cap having a sensor holder portion fixed to the outer ring of the bearing and holding the sensor in a wheel bearing device provided with a sensor for detecting the rotation of an encoder fixed to the inner ring of the bearing. And
The insert nut is
One of both ends in the axial direction of the through hole in the axial direction is used as the end on the pin insertion side into which the support pin of the injection molding die is inserted.
In the through hole, the screw portion into which a bolt can be screwed from the end on the pin insertion side is formed.
The other end of the axial end of the through hole has a non-threaded portion that does not form the threaded portion.
The inner peripheral surface of the non-threaded portion is formed with a stepped portion by providing a small diameter portion having an inner diameter smaller than the prepared hole diameter of the threaded portion.
The injection molding mold is opened, and a stepped support pin having a small diameter portion formed at the tip of the mold that fits into the small diameter portion of the insert nut is inserted from the pin insertion side end of the insert nut. The insert nut is set on the support pin so as to be inserted into the through hole, only the small diameter portion of the insert nut is fitted into the small diameter portion of the support pin, and the step portion of the insert nut is the support pin. And the process of making it in contact with the end face of
A step of filling the molten resin material into the mold with the mold closed and the mold tightened.
After cooling and solidifying the molten resin material, the mold is opened and the resin cap, which is a molded product, is taken out.
Only including,
The axial length of the non-threaded portion of the insert nut is 0.5 mm or more and 2 mm or less.
The fitting gap between the inner peripheral surface of the non-threaded portion of the insert nut and the tip end portion of the outer peripheral surface of the support pin is 0.01 to 0.15 mm in diameter (claim 3 ).

According to such a manufacturing method, when the insert nut is set on the support pin, the step portion of the insert nut is in contact with the end face of the support pin, so the mold is closed, the mold is tightened, and the mold is melted in the mold. When the step of filling the resin material is performed, it is possible to prevent the molten resin from entering the threaded portion of the insert nut.
Further, by setting the axial length of the non-threaded portion of the insert nut to 0.5 mm or more and 2 mm or less, the total length of the insert nut can be increased while having the effect of suppressing the intrusion of the molten resin into the insert nut. Can be relatively short.
Further, by setting the fitting gap between the inner peripheral surface of the non-threaded portion of the insert nut and the tip end portion of the outer peripheral surface of the support pin to a diameter of 0.01 to 0.15 mm, the insert nut is said to have a diameter of 0.01 to 0.15 mm. The resin does not wrap around in the structure in which only the small diameter portion is fitted to the small diameter portion of the support pin.

According to the production method of the present invention in engagement Ru resin cap as described above, while ensuring the required length of the useful thread of the insert nut having an axial through hole, the length of the insert nut as much as possible short Therefore, it is possible to meet the need for miniaturization of reducing the thickness of the resin portion in which the insert nut is embedded in the resin cap.

The insert nut according to the embodiment of the present invention is shown, (a) is a perspective view, and (b) is a vertical sectional view. It is a vertical cross-sectional perspective view which shows the sensor cap which has the sensor holder part which is the resin cap in which the insert nut is embedded. It is also a vertical sectional view. It is a vertical cross-sectional perspective view which shows the state which attached the sensor to the sensor cap. It is a vertical sectional view of the bearing device for a wheel. It is an enlarged vertical sectional view of the main part of the injection molding die used in the manufacturing method of the resin cap which concerns on embodiment of this invention. It is an enlarged vertical cross-sectional view of the main part which shows the insert nut and the support pin of the injection molding die which concerns on embodiment of this invention, (a) is the state before attaching the insert nut to the support pin, (b) is the insert. It shows the state where the nut is attached to the support pin. It is an enlarged vertical cross-sectional view of a main part which shows the support pin of a conventional insert nut and an injection molding die, (a) is the state before attaching the insert nut to a support pin, and (b) is the state before attaching an insert nut to a support pin. Shows the state. It is a vertical cross-sectional view which shows the deformation example of an insert nut, (a) is an example which made the inner peripheral surface of a non-threaded part a tapered surface, and changed the axial position of a peripheral groove, (b) is the inside of a non-threaded part. An example in which a small diameter portion is provided on the peripheral surface and the axial position of the peripheral groove is changed, (c) is an example in which a plurality of peripheral grooves are provided, and (d) is an example in which a large chamfer is provided at the end on the pin insertion side. There is. 9 is an enlarged vertical cross-sectional view of a main part showing a state in which the insert nut of FIG. 9A is attached to a support pin of an injection molding die. 9 is an enlarged vertical cross-sectional view of a main part showing a state in which the insert nut of FIG. 9B is attached to a support pin of an injection molding die.

Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings, but the present invention is not limited to the embodiments shown in the accompanying drawings, and includes all embodiments that satisfy the requirements described in the claims. It is a waste.
The insert nut 1 shown below is manufactured from a metal material such as brass, stainless steel, titanium, aluminum, or iron. When the insert nut 1 is manufactured from an iron-based material, it is desirable to perform a plating treatment. Further, when the insert nut 1 is used for the sensor cap 11 which is an undercarriage component of an automobile, it is exposed to harsh conditions such as wind and snow, wind and rain, and a snow melting agent containing calcium chloride as a main component, so that the material of the insert nut 1 is used. In the present specification, the axial direction of the mounting bolt 15 screwed into the female screw (threaded portion 3) of the insert nut 1 is defined as “axial direction”.

<Insert nut>
As shown in the perspective view of FIG. 1A and the vertical sectional view of FIG. 1B, the metal insert nut 1 according to the embodiment of the present invention has an axial through hole 2 and penetrates. For injection molding, one end 2A of both ends 2A and 2B in the axial direction of the hole 2 is shown in the enlarged vertical cross-sectional view of the main part of FIG. 6 and the enlarged vertical cross-sectional view of the main part of FIGS. 7A and 7B. It is a pin insertion side end portion B into which the support pin 20 of the mold A is inserted.
Further, in the through hole 2 of the insert nut 1, the screw portion 3 is a female screw into which the mounting bolt 15 shown in the vertical sectional perspective view of FIG. 4 and the vertical sectional view of FIG. 5 can be screwed from the pin insertion side end portion B. The other end 2B of both axial end portions 2A and 2B of the through hole 2 has a non-threaded portion 4 that does not form a threaded portion 3.
Here, the inner peripheral surface of the non-threaded portion 4 is a pilot hole 4A to be drilled before forming the threaded portion 3.
Further, a peripheral groove 7 is formed on the outer peripheral surface of the insert nut 1.

Here, it is a preferable embodiment that the axial length of the non-threaded portion 4 is 0.5 mm or more and 2 mm or less.
The axial length of the non-threaded portion 4 can be changed according to the required specifications, and 0.5 mm or more and 2 mm or less is a preferable range from a practical point of view. That is, if the axial length of the non-threaded portion 4 is within the above range, the total length of the insert nut 1 can be relatively shortened while having the effect of suppressing the intrusion of the molten resin into the insert nut 1, which will be described later.
Further, since the end portion 2B of the insert nut 1 is provided with the non-threaded portion 4, the tap for forming the female screw 3 does not penetrate, so that the threaded portion 3 which is a female screw on the inner surface of the side wall forming the through hole 2 in the axial direction. Since it is not necessary to chamfer the end face 2B, which also serves as a deburring, as in the case where a female screw is machined by penetrating a tap in a conventional insert nut formed over the entire length, an effective screw by the chamfering is not required. There is no reduction in the part.

<Resin cap>
As shown in the vertical sectional perspective view of FIG. 2, the vertical sectional view of FIG. 3, and the vertical sectional perspective view of FIG. 4, the sensor cap 11 which is a resin cap according to the embodiment of the present invention has a cylindrical steel plate. The insert nut 1 is composed of a cylindrical member 12, an insert nut 1, a disk-shaped member 13 which is a synthetic resin R, and the like, and the threaded portion 3 of the insert nut 1 is exposed while being embedded in the synthetic resin R.
The disk-shaped member 13 holds the main body 13A to which the cylindrical member 12 and the outer peripheral portion are coupled, and the insert nut 1 into which the mounting bolt 15 for mounting the magnetic sensor 10 is screwed, and the magnetic sensor 10 is inserted. It has a sensor holder portion 13B in which a sensor mounting hole 14 is formed.
Here, the sensor cap 11 is an insert molded product, and the metal cylindrical member 12 and the insert nut 1 are insert products.

<Wheel bearing device>
As shown in the vertical sectional view of FIG. 5, the wheel bearing device 21 to which the sensor cap 11 is attached includes a magnetic encoder 16 and a magnetic sensor 10 in addition to a bearing in which the inner ring 22 rotates with respect to the outer ring 23.
The bearing rolls between the inner ring 22 having the inner ring raceway surface 22A formed on the outer peripheral surface, the outer ring 23 having the outer ring raceway surface 23A formed on the inner peripheral surface, and the inner ring raceway surface 22A and the outer ring raceway surface 23A. It has rolling elements 24, 24, ..., Etc.
The magnetic encoder 16 has N poles and S poles arranged alternately in the circumferential direction at regular intervals, and is fixed to the inner ring 22 by a support member 17 located at one end in the axial direction of the bearing.
Further, the sensor cap 11 is fixed to the outer ring 23 of the bearing by press-fitting the cylindrical member 12 into the outer ring 23 of the bearing, and seals one end of the bearing in the axial direction and holds the magnetic sensor 10. It has a part 13B.
Further, the magnetic sensor 10 mounted on the sensor holder portion 13B of the sensor cap 11 faces the magnetic encoder 16 and detects the rotation of the magnetic encoder 16.
Further, the bearing device 21 includes a seal member 25 or the like arranged at the other end of the bearing in the axial direction.

<Manufacturing method of resin cap>
Next, regarding the method of manufacturing the sensor cap 11 of FIGS. 2 and 3 which is the resin cap according to the embodiment of the present invention, the injection molding die A shown in the enlarged vertical sectional view of the main part of FIG. 6 and FIG. 7 This will be described with reference to the support pins 20 shown in the enlarged vertical sectional views of the main parts of (a) and (b).
As the resin material used, for example, polyamide (nylon 6, nylon 66, nylon 612, etc.), polyphenylene sulfide (PPS), or polybutylene terephthalate (PBT) containing 20 to 70% by weight of glass fiber is used.

First, the injection molding die A is opened, and the support pin 20 of the die A (fixed die 18) is inserted into the through hole 2 from the pin insertion side end B of the insert nut 1. The insert nut 1 is set on the support pin 20, and the non-threaded portion 4 of the insert nut 1 is fitted into the tip portion 20A of the support pin 20. The gap between the inner peripheral surface (prepared hole 4A) of the non-threaded portion 4 of the insert nut 1 and the tip portion 20A of the outer peripheral surface of the support pin 20 is formed by the resin depending on the fluidity of the resin material used. Set to a range that does not wrap around. The gap is set, for example, in the range of 0.01 to 0.15 mm in diameter.
Since the tip end side portion 20B of the support pin 20 is a tapered surface having a gentle inclination that shrinks in diameter as it approaches the tip end, the insert nut 1 can be easily set.
Further, the cylindrical member 12 which is an insert product is set in the movable mold 19.

Next, in a state where the fixed mold 18 and the movable mold 19 attached to the injection molding machine are molded, the molten resin material is injected from the sprue and filled in the cavity C between the fixed mold 18 and the movable mold 19 from the gate G. To do.

Next, after the molten resin material is cooled and solidified, the mold A is opened and the sensor cap 11 which is a molded product is taken out.

In the sensor cap 11 manufactured through the injection molding as described above, since the synthetic resin has entered the peripheral groove 7 of the insert nut 1, the insert nut 1 is prevented from coming off.
Further, since the outer peripheral portion of the main body portion 13A wraps around the bent portion at the axial end of the cylindrical member 12, the cylindrical member 12 and the disk-shaped member 13 are mechanically coupled.

(Injection molding of resin cap including conventional insert nut)
Here, as shown in the enlarged vertical sectional views of the main parts of FIGS. 8A and 8B, the female screw 3 extends over the entire length on the inner surface of the side wall forming the conventional axial through hole 2 without the non-threaded portion 4. When injection molding is performed with the formed insert nut 1A set on the support pin 20 of the mold A, the molten resin injected into the mold A is spirally formed by the female screw of the insert nut 1A due to the pressure. It is easy to penetrate into the insert nut 1A along the thread of the screw, and the distance (axial length) at which the molten resin penetrates into the insert nut 1A becomes large.

(Injection molding of a resin cap including an insert nut according to an embodiment of the present invention)
On the other hand, the insert nut 1 according to the embodiment of the present invention, which has the non-threaded portion 4 as shown in the enlarged vertical sectional view of the main part of FIGS. 7A and 7B, is supported by the support pin of the mold A. When injection molding is performed with the insert nut 1 set in the mold A, the non-threaded portion 4 of the insert nut 1 fits in the tip portion 20A of the support pin 20 when the insert nut 1 is set in the support pin 20 of the mold A.
Therefore, when the mold A is closed, the mold is tightened, and the molten resin material is filled in the mold A, the inner peripheral surface (prepared hole 4A) of the non-threaded portion 4 of the insert nut 1 is supported. The non-threaded portion 4 having no spiral thread is set by setting the fitting gap of the outer peripheral surface of the pin 20 with the tip portion 20A so that the resin does not wrap around according to the fluidity of the resin material used. However, since it has the effect of blocking the intrusion of the molten resin injected into the mold A into the insert nut 1, it is possible to suppress the intrusion of the molten resin into the insert nut 1, and the molten resin is the insert nut 1. The distance (axial length) that penetrates inside does not vary greatly.
Therefore, the length of the insert nut 1 can be shortened as much as possible while ensuring the required length of the effective screw portion of the insert nut 1, so that the thickness of the resin portion in which the insert nut 1 is embedded in the sensor cap 11 is reduced. It can meet the needs for miniaturization.

<Modification example of insert nut>
Next, a modified example of the insert nut 1 will be described.

The vertical cross-sectional view of FIG. 9A shows an example in which the inner peripheral surface of the non-threaded portion 4 is made a tapered surface 5 and the axial position of the peripheral groove 8 is changed. An example is shown in which a small diameter portion 6A is provided on the inner peripheral surface of the non-threaded portion 4 and the axial position of the peripheral groove is changed.
That is, the inner peripheral surface of the non-threaded portion 4 in the example of FIG. 9A is a tapered surface 5 whose diameter is reduced as it goes away from the pin insertion side end portion B (as it approaches the end portion 2B), and is shown in FIG. A step portion 6B is formed on the inner peripheral surface of the non-threaded portion 4 in the example (b) by providing a small diameter portion 6A having an inner diameter smaller than the prepared hole diameter of the threaded portion 3.

FIG. 10 is an enlarged vertical cross-sectional view of a main part showing a state in which the insert nut 1 of FIG. 9A is attached to the support pin 20 of the injection molding die A, and the insert nut 1 is attached to the tip of the support pin 20. A tapered surface 20C in contact with the tapered surface 5 of the above is formed.
In the state where the insert nut 1 is set on the support pin 20 in this way, the tapered surface 5 of the insert nut 1 is in contact with the tapered surface 20C of the support pin 20, so the mold A is closed and the mold A is tightened. When the step of filling the molten resin material into the inside is performed, it is possible to prevent the molten resin from invading the threaded portion 3 of the insert nut 1.

FIG. 11 is an enlarged vertical cross-sectional view of a main part showing a state in which the insert nut 1 of FIG. 9B is attached to the support pin 20 of the injection molding die A, and the tip of the support pin 20 is the tip of the insert nut 1. It has a stepped shape in which a small diameter portion 20D fitted to the small diameter portion 6A is formed.
In the state where the insert nut 1 is set on the support pin 20 in this way, the step portion 6B of the insert nut 1 is in contact with the large-diameter side end surface 20E of the support pin 20, so the mold A is closed and the mold is tightened. When the step of filling the mold A with the molten resin material is performed, it is possible to prevent the molten resin from entering the threaded portion 3 of the insert nut 1.

Further, in FIGS. 9A and 9B, the peripheral groove 8 formed on the outer peripheral surface of the insert nut 1 is located at a position offset from the central portion in the axial direction toward the end portion 2B, so that the insert nut 1 Is set on the support pin 20 of the mold A, the pin insertion side end portion B can be easily recognized.
The peripheral groove 8 may be offset from the central portion in the axial direction toward the end portion 2A (pin insertion side end portion B).

The vertical cross-sectional view of FIG. 9C is an example in which three peripheral grooves 9A, 9B, and 9C are formed on the outer peripheral surface of the insert nut 1, and the vertical cross-sectional view of FIG. 9D is the pin insertion side end portion. An example in which a large chamfer D is provided on D is shown.
As described above, the position and number of the peripheral grooves, the chamfering of the end portion, and the like can be appropriately changed according to the required specifications of the insert nut 1.

1,1A Insert nut 2 Through hole 2A, 2B End 3 Threaded part 4 Non-threaded part 4A Pilot hole 5 Tapered surface 6A Small diameter part 6B Step part 7,8,9A, 9B, 9C Circumferential groove 10 Magnetic sensor 11 Sensor cap ( Resin cap)
12 Cylindrical member 13 Disc-shaped member 13A Main body 13B Sensor holder 14 Sensor mounting hole 15 Mounting bolt 16 Magnetic encoder 17 Support member 18 Fixed type 19 Movable type 20 Support pin 20A Tip part 20B Tip side part 20C Tapered surface 20D Small diameter part 20E Large-diameter side end surface 21 Wheel bearing device 22 Inner ring 22A Inner ring raceway surface 23 Outer ring 23A Outer ring drive surface 24 Rolling element 25 Sealing member A Injection molding mold B Pin insertion side end C Cavity D Chamfering G Gate R Synthetic resin

Claims (3)

A method for manufacturing a resin cap in which a metal insert nut is embedded in a synthetic resin.
The resin cap is a sensor cap having a sensor holder portion fixed to the outer ring of the bearing and holding the sensor in a wheel bearing device provided with a sensor for detecting the rotation of an encoder fixed to the inner ring of the bearing. And
The insert nut is
One of both ends in the axial direction of the through hole in the axial direction is used as the end on the pin insertion side into which the support pin of the injection molding die is inserted.
In the through hole, the screw portion into which a bolt can be screwed from the end on the pin insertion side is formed.
The other end of the axial end of the through hole has a non-threaded portion that does not form the threaded portion.
The inner peripheral surface of the non-threaded portion is a pilot hole to be drilled before forming the threaded portion.
The injection mold is opened, the insert nut is set in the support pin so that the support pin of the mold is inserted into the through hole from the pin insertion side end of the insert nut, and the insert nut is set. The step of fitting only the non-threaded portion of the above to the tip of the support pin, and
A step of filling the molten resin material into the mold with the mold closed and the mold tightened.
After cooling and solidifying the molten resin material, the mold is opened and the resin cap, which is a molded product, is taken out.
Only including,
The axial length of the non-threaded portion of the insert nut is 0.5 mm or more and 2 mm or less.
The fitting gap between the inner peripheral surface of the non-threaded portion of the insert nut and the tip end portion of the outer peripheral surface of the support pin is 0.01 to 0.15 mm in diameter.
How to manufacture a resin cap. A method for manufacturing a resin cap in which a metal insert nut is embedded in a synthetic resin.
The resin cap is a sensor cap having a sensor holder portion fixed to the outer ring of the bearing and holding the sensor in a wheel bearing device provided with a sensor for detecting the rotation of an encoder fixed to the inner ring of the bearing. And
The insert nut is
One of both ends in the axial direction of the through hole in the axial direction is used as the end on the pin insertion side into which the support pin of the injection molding die is inserted.
In the through hole, the screw portion into which a bolt can be screwed from the end on the pin insertion side is formed.
The other end of the axial end of the through hole has a non-threaded portion that does not form the threaded portion.
The inner peripheral surface of the non-threaded portion has a tapered surface whose diameter decreases as the distance from the pin insertion side end portion increases.
The injection molding die is opened, and a support pin having a tapered surface formed at the tip of the mold in contact with the tapered surface of the insert nut is inserted into the through hole from the pin insertion side end of the insert nut. A step of setting the insert nut on the support pin so that only the tapered surface of the insert nut is in contact with the tapered surface of the support pin.
A step of filling the molten resin material into the mold with the mold closed and the mold tightened.
After cooling and solidifying the molten resin material, the mold is opened and the resin cap, which is a molded product, is taken out.
Only including,
The axial length of the non-threaded portion of the insert nut is 0.5 mm or more and 2 mm or less.
The fitting gap between the inner peripheral surface of the non-threaded portion of the insert nut and the tip end portion of the outer peripheral surface of the support pin is 0.01 to 0.15 mm in diameter.
How to manufacture a resin cap. A method for manufacturing a resin cap in which a metal insert nut is embedded in a synthetic resin.
The resin cap is a sensor cap having a sensor holder portion fixed to the outer ring of the bearing and holding the sensor in a wheel bearing device provided with a sensor for detecting the rotation of an encoder fixed to the inner ring of the bearing. And
The insert nut is
One of both ends in the axial direction of the through hole in the axial direction is used as the end on the pin insertion side into which the support pin of the injection molding die is inserted.
In the through hole, the screw portion into which a bolt can be screwed from the end on the pin insertion side is formed.
The other end of the axial end of the through hole has a non-threaded portion that does not form the threaded portion.
The inner peripheral surface of the non-threaded portion is formed with a stepped portion by providing a small diameter portion having an inner diameter smaller than the prepared hole diameter of the threaded portion.
The injection molding mold is opened, and a stepped support pin having a small diameter portion formed at the tip of the mold that fits into the small diameter portion of the insert nut is inserted from the pin insertion side end of the insert nut. The insert nut is set on the support pin so as to be inserted into the through hole, only the small diameter portion of the insert nut is fitted into the small diameter portion of the support pin, and the step portion of the insert nut is the support pin. And the process of making it in contact with the end face of
A step of filling the molten resin material into the mold with the mold closed and the mold tightened.
After cooling and solidifying the molten resin material, the mold is opened and the resin cap, which is a molded product, is taken out.
Only including,
The axial length of the non-threaded portion of the insert nut is 0.5 mm or more and 2 mm or less.
The fitting gap between the inner peripheral surface of the non-threaded portion of the insert nut and the tip end portion of the outer peripheral surface of the support pin is 0.01 to 0.15 mm in diameter.
How to manufacture a resin cap.

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