JPH0757502B2 - Method of manufacturing timepiece slip mechanism - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a slip mechanism used in a pointer type timepiece.

[0002]

2. Description of the Related Art Generally, a pointer type timepiece transmits the rotation of a drive source such as a step motor to a pointer such as an hour hand and a minute hand through a train wheel mechanism, and moves the hands to indicate the time. Has become. Further, in the pointer type timepiece, the minute hand and the hour hand are rotated at the time of hand setting, but the second hand and the step motor are not rotated. Therefore, the second wheel to which the minute hand is attached has a slip mechanism. .
That is, the second wheel & pinion has a structure in which a gear part with which the third wheel is meshed is integrally mounted so as to be capable of slip rotation, on a shaft part having a cylindrical pinion that meshes with the Hino back wheel. The shaft portion and the shaft portion rotate integrally, and the rotation of the step motor is transmitted to the minute hand and the hour hand. On the other hand, when adjusting the hands, the rotational force from the correction mechanism is transmitted to the cylindrical pinion of the shaft portion, and the time correction mechanism applies a torque (load) above a certain level to the cylindrical pinion of the shaft portion. Then, the shaft portion rotates but the gear portion does not rotate. As a result, the minute hand and hour hand rotate, but the second hand and step motor do not rotate.

In such a slip mechanism, conventionally, the gear and shaft of a center wheel & pinion are made of metal, and a pair of leaf spring-like elastic pieces are provided on the metal gear, and the pair of elastic pieces make the shaft. The part is elastically clamped. Therefore, there are drawbacks that the number of parts is large, the assembling work is complicated, a stable slip torque cannot be obtained, and since it is made of metal, the machining is troublesome and the cost is high.

Therefore, the applicant of the present application considered earlier that the shaft portion and the gear portion are formed of a synthetic resin, and that they are integrally molded so that they can slip and rotate.
1-178003). This is the primary molding of the shaft,
This shaft portion is arranged in a secondary molding (gear portion molding) die, and resin is poured into the die to integrally mold the gear portion on the shaft portion so as to allow slip rotation.

[0005]

In the method of manufacturing the slip mechanism as described above, when molding the gear part, the high temperature molten resin flows directly into the slip surface of the shaft part while keeping the high temperature, and the shaft part and the gear part There is a problem that the slip torque becomes extremely large due to the fusion of the parts. The present invention has been made in view of the above circumstances, and when a synthetic resin gear part is integrally molded integrally with a synthetic resin shaft part so as to allow slip rotation, the gear part is fused to the shaft part. It is an object of the present invention to provide a method for manufacturing a slip mechanism for a timepiece that is free from problems and that can obtain an appropriate and stable slip torque.

[0006]

In order to achieve the above object, the position of a resin injection gate of a mold for molding a gear part is provided on one side surface of the gear part in the axial direction of the shaft part. An annular protrusion is provided closer to the center than the resin injection gate on the other side facing the side.

[0007]

The high-temperature resin injected from the resin injection gate does not flow directly in the axial direction, hits once on the opposite surface of the mold, crosses the annular projection, and then heads toward the axial projection. It takes time to reach the joint protrusion of the shaft part, and it is possible to reliably prevent fusion of the gear part to the shaft part due to loss of heat due to flow resistance, which lowers the resin temperature. Stable slip torque can be obtained.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. Structure FIG. 1 shows an analog movement of an electronic wristwatch using a center wheel and pinion manufactured by the method for manufacturing a timepiece slip mechanism according to the present invention. This analog movement transmits the rotation of the step motor 1 to the train wheel mechanism 2, and the train wheel mechanism 2 moves the hands such as the hour hand 3a, the minute hand 3b, and the second hand 3c to indicate the time, and the time adjustment mechanism displays the hands. It is designed for needle matching.

The step motor 1 is a drive source for moving a pointer, and is composed of a rotor 5, a stator (not shown), a coil, etc., and the rotor 5 steps by 180 degrees each time an inversion pulse of a constant cycle is given to the coil. It is designed to rotate. In this case, as shown in FIG. 1, the rotor 5 is composed of a rotor portion 5a, a rotor pinion 5b, a rotor shaft 5c, etc., which are integrally formed of a polyacetal resin containing potassium titanate whiskers, and the rotor portion 5a
The magnet ring 5d is attached to the
A rotor shaft 5c is rotatably attached between the main plate 6 and the train wheel bridge 7.

The train wheel mechanism 2 transmits the rotation of the step motor 1 to the pointer to move the pointer. The intermediate wheel 8,
It consists of the 4th wheel 9, the 3rd wheel 10, the 2nd wheel 11, the Hino back wheel 12, the hour wheel 13 and the like, and the intermediate wheel 8, the 4th wheel 9 and the 3rd wheel between the main plate 6 and the wheel bridge 7. A wheel 10 is mounted on the main plate 6, and a center wheel & pinion 11, a Hino back wheel 12, and a hour wheel 13 are mounted on the ground plate 6, respectively. In this case, the main plate 6 and the train wheel bridge 7 are made of polyphenylene sulfide resin (hereinafter,
It is made of "PPS resin"), and a dial 14 is provided on the base plate 6.

Hereinafter, each vehicle will be described in order. The intermediate wheel 8 meshes with the rotor pinion 5b of the step motor 1 to rotate, is made of polyacetal resin containing potassium titanate whiskers, and has a shaft portion 8a and an intermediate pinion 8b.
It is molded integrally with.

The fourth wheel & pinion 9 rotates by meshing with the intermediate pinion 8b of the intermediate wheel 8 to move the second hand 3c, and its shaft portion 9a constitutes the second hand shaft, and the bearing portion 6a of the main plate 6 and the dial plate 14 are provided. Projecting upward through this, and this protruding portion serves as a needle mounting portion 9c, and the second hand 3c is attached to this needle mounting portion 9c.
Is attached. The fourth wheel & pinion 9 is made of a liquid crystal polymer resin containing potassium titanate whiskers and is integrally formed with the shaft portion 9a and the fourth pinion 9b.

The third wheel & pinion 10 rotates by meshing with the fourth wheel & pinion 9b of the fourth wheel & pinion 9, made of polyacetal resin containing potassium titanate whisker, and formed integrally with the shaft portion 10a and the third wheel & pinion 10b. There is. In this case, the third pinion 10b penetrates the main plate 6 and projects above it.

The second wheel 11 is the third wheel 10b of the third wheel 10.
The shaft portion 11a serves as a minute hand shaft and is rotatably attached to the outer periphery of the bearing portion 6a of the main plate 6, and the upper end of the shaft portion 11a is connected to the dial plate 14a. The minute hand 3b is attached to the protruding portion. The center wheel & pinion 11 is formed by integrally forming a shaft portion 11a having a cylindrical pinion portion 11b and a gear portion 11c in a two-color manner so as to enable slip rotation.
The shaft portion 11a has high wear resistance and strength, and the gear portion 11c
PP containing potassium titanate whisker with higher melting temperature
The gear portion 11c is made of S resin, and the gear portion 11c is made of 12 nylon resin containing potassium titanate whiskers, which has a low shrinkage ratio and a melting temperature lower than that of the shaft portion 11a.

The center wheel & pinion 11 is constructed as shown in FIG. That is, the shaft portion 11a has a tubular shape, and a cylindrical pinion portion 11b is formed in the lower portion of the shaft portion 11a, and the inside of the cylindrical pinion portion 11b is a large diameter portion a, and the outer periphery of the cylindrical pin portion 11b is a protruding portion for joining. c and an extension part d are formed. Also, the shaft portion 11
The inside of the upper side of a is a small diameter portion e, and a relief portion f and a needle mounting portion g are formed on the outer periphery thereof. Tube kana part 1
In 1b, the large diameter portion a is rotatably fitted to the outer periphery of the bearing portion 6a of the main plate 6, and the extending portion d at the lower end thereof protrudes downward so that it extends around the bearing portion 6a of the main plate 6. It is rotatably inserted into the formed annular recessed groove 6b, whereby the shaft portion 11a is held sufficiently long so as not to run out. Further, the pinion b provided on the outer periphery is one in which the teeth of the Hino back wheel 12 mesh with each other.

The protrusion c is a portion gear portion 11c is formed integrally, formed on the lower side of the pinion b is formed in a flange shape, the inclined surface c _a where the outer periphery is inclined toward the lower side The lower surface of the protrusion c is a molding die 15, which will be described later,
It has 15 mating surfaces. In this case, the outer diameter c ₁ of the tip of the protrusion c is about 2.1 mm, and the angle α of the tip is 74 mm.
It has become °. The gear portion 11c integrally formed with the protrusion c has an outer diameter of about 3.4 mm and a thickness t ₁ thereof.
Is about 0.3 mm, which is thicker than the protruding portion c, and the thickness t ₂ protruding to the lower side is about 0.05 mm, which penetrates into the protruding portion c. A plurality of resin injecting gates G ... Are provided near the outer periphery of the lower surface of the gear portion 11c.
The cylindrical pinion 1 of the shaft 11a is on the upper surface on the side opposite to
A "V" -shaped recess j that changes the flow direction of the resin at the time of molding is formed near the side 1b over the entire circumference. The depth “t ₃ ” of the “V” -shaped concave portion “j” is ₁ of the thickness t ₁ of the gear portion 11 c.
It is formed to about ⅓. As a result, the center wheel & pinion 11 has an appropriate slip torque (3 to 6 g · cm), and the cylindrical pinion portion 11b is subjected to a torque (load) higher than this.
The (shaft portion 11a) and the gear portion 11c mutually perform slip rotation.

Further, the small-diameter portion e on the upper side of the shaft portion 11a is inserted so that the shaft portion 9a of the fourth wheel & pinion 9 does not come into contact therewith. The relief portion f formed on the outer periphery of the shaft portion 11a is located at a portion corresponding to the needle mounting portion 13b of the hour wheel 13 and has a predetermined clearance at that portion, and the hour hand 3a
2nd wheel 11 even if the needle mounting portion 13b is deformed when mounting
It does not come into contact with the shaft portion 11a. The needle mounting portion g at the upper end is a portion where the minute hand 3b is fitted.

Molding of the center wheel & pinion 11 is carried out using molds 15 and 16 as shown in FIGS. 3A and 3B. The molds 15 and 16 are turntable molds. It is incorporated into the automatic insert molding machine of. Therefore, as shown in FIG. 3A, the shaft portion 11a having the cylindrical pinion portion 11b is injection-molded by the pair of upper and lower primary molding dies 15 and 15. The upper and lower dies 15 and 15 are formed by injection molding. Is the parting line PL, that is, the joint surfaces of the upper and lower molds 15, 15 are located on the lower surface of the protruding portion c of the shaft portion 11a,
This prevents the eccentricity of the tips of the protrusions c due to the displacement of the upper and lower molds 15, 15. Such a mold 1
The resin pellets used when molding the shaft portion 11a with Nos. 5 and 15 are crystalline PPS resin containing potassium titanate whisker mixed with a few percent of silicon-based oil having heat resistance of 250 ° C. or higher. Gate G for shaft 11
It is provided on the upper end surface of a.

The shaft portion 11a molded in this way is
After being taken out from the primary molding dies 15 and 15, FIG.
A pair of upper and lower secondary molding dies 16 and 1 as shown in FIG.
6, the resin for secondary molding is injected from the resin injection gate G provided on the lower mold 16, and the gear 11c is integrally formed on the shaft 11a which is the primary molding. To mold. In this case, the resin injecting gate G is located on the outer peripheral side of the lower surface, and a "V" for forming a "V" -shaped recess j on the opposite side surface, that is, the inner upper surface of the upper die 16.
A character-shaped protruding portion 16a is formed in an annular shape so as to protrude in the cavity. Therefore, the resin is the resin injection gate G ...
When injected from the inside into the cavity, as shown in FIG. 3 (B), the protrusion 16 for molding the recess j formed on the opposite side surface is formed.
Due to a, the high-temperature resin does not directly flow into the protruding portion c of the cylindrical pinion portion 11b, but its flow direction changes to a direction in which it returns to the gate G.

As a result, it takes time for the injected high temperature resin to reach the tip of the protrusion c, and the amount of heat is lost due to the flow resistance and the resin temperature drops to some extent. Does not melt. The resin pellets used here are 250
It is a 12-nylon resin containing crystalline potassium titanate whiskers, which is a mixture of several percent of a silicon-based oil having heat resistance of ℃ or more. The molded product (second wheel & pinion 11) molded in this way is immersed in silicon oil having a dimethylsiloxane structure and having a high temperature of about 100 ° C. for about 3 hours for oil annealing. In this case, the temperature of the silicone oil may be about 80% of the heat distortion temperature and may be 1 hour or more. Then, the center wheel & pinion 11 as shown in FIG. 2 is obtained.

The Hino Ura Kurashi 12 is the cylindrical pinion 11 of the second wheel 11.
The shaft part that meshes with the pinion b formed in b and rotates, and is made of polyacetal resin containing potassium titanate whisker, is integrally formed with the Hinoura kana 12b, and is formed to project on the upper surface of the main plate 6. It is rotatably attached to 6c. In this case, the Hino back wheel 12 is pressed from above by the Hino back presser 12c.

The hour wheel 13 meshes with the pinion 12b of the Hino back wheel 12 and rotates to move the hour hand 3a. The hour wheel 3a is made of polyacetal resin containing potassium titanate whisker, and its shaft portion 13a has a tubular shape. Shaft 1 of the second wheel 11
It is rotatably attached to the outer periphery of 1a, and its upper end is a dial 1
4 above, and this protruding portion is the needle mounting portion 13b.
The hour hand 3a is press-fitted and attached to the hand attaching portion 13b.

[0023]Action  Next, the analog movement configured as above
The operation of will be described. Normally by step motor 1
The pointer moves to indicate the time. That is, as shown in FIG.
As the rotor 5 of the step motor 1 rotates,
The rotation is transmitted to the fourth wheel 9 through the intermediate wheel 8,
The wheel 9 rotates and is attached to the upper end of the shaft 9a of the fourth wheel & pinion 9.
The second hand 3c thus set is moved. In addition, the fourth wheel 9
When the wheel rotates, the rotation of the wheel shifts through the third wheel 10 to the second wheel 1
The second wheel & pinion 11 is transmitted by being transmitted to 1. In this case, number two
The wheel 11 has a shaft 11a and a gear 11c that can slip and rotate.
It is formed integrally with Noh, but in this state the second wheel 1
1 does not receive a certain load, so shaft 11a and teeth
The car part 11c rotates integrally. Therefore, the second wheel 1
The minute hand 3b attached to the first shaft portion 11a moves.
When the center wheel & pinion 11 rotates like this, the rotation is
It is transmitted to the hour wheel 13 via the wheel 12, and the hour wheel 13 rotates.
To move the hour hand 3a. In this way, the hour hand 3a and minute hand 3
b, since the second hand 3c moves above the dial 14,
Will be displayed.

When the time is adjusted, the winding stem of the time adjusting mechanism (not shown) may be pulled out and turned a predetermined amount. Then, the center wheel & pinion 11 and the hour wheel 13 rotate, and the hour hand 3
The hands are aligned by rotating a and the minute hand 3b. At this time, torque (rotational force) is applied to the center wheel & pinion 11 from the winding stem, but when the torque (rotational force) from the winding stem becomes equal to or greater than the slip torque (3 to 6 g · cm) of the second wheel & pinion 11, The shaft 11a of the center wheel & pinion 11 slips between the gear 11c and the shaft 11a slips and rotates. Moreover, when the shaft portion 11a slips and rotates in this manner, a thin film of silicon-based oil is formed on the contact surface between the shaft portion 11a and the gear portion 11c, and this film acts as a lubricant to prevent the shaft portion 11a from contacting with the shaft portion 11a. The gear portion 11c and the gear portion 11c rotate smoothly with a stable slip torque. Therefore, the hands can be aligned with each other without rotating the second hand.

However, according to the method of manufacturing the slip mechanism for a timepiece as described above, the gear portion 11c is formed when slip-rotatably integrally formed on the shaft portion 11a made of synthetic resin having the cylindrical pinion portion 11b. The resin injection gate G of the secondary molding die is provided on one side surface in the axial direction of the gear portion 11c, and the resin flow gate "V" is provided on the opposite side surface to change the flow direction of the resin toward the protruding portion c of the cylindrical pinion portion 11b. Character-shaped protrusion 16a
Is formed over the entire circumference, the high temperature resin injected from the resin injecting gate G when the gear portion 11c is molded does not directly flow into the protruding portion c of the cylindrical pinion portion 11b by the protruding portion 16a. The flow direction changes to return to the gate G ... side. Therefore, it takes time for the high-temperature resin to reach the tip of the protrusion c, and the amount of heat is lost due to the flow resistance, and the resin temperature decreases to some extent.
It is possible to obtain stable and appropriate slip torque with excellent rotation characteristics without being fused to the tip of the protrusion c.

Although the gear portion 11c is formed with the "V" -shaped concave portion j in the above-described embodiment, the present invention is not limited to this, and as shown in FIGS. Concave part j
Even _a, may be a "U" shaped recess j _b, short be any shape, such as changing the flow direction of the resin may be any shape. Further, the concave portion j is the gear portion 11c.
4 (c) to (e), when the resin injection gate G ... Is on the upper surface side, a "V" shape, a rectangular shape is formed on the lower surface side opposite to the upper surface. The concave portions j, j _a , and j _b having _a shape of “U” may be formed. Furthermore, although in the embodiment described above to form the tip of the protrusion c which is formed in a cylindrical pinion portion 11b of the shaft portion 11a to the inclined surface c _a, the present invention is not limited to this, FIG. 4 (f) (g) as shown in, Yamagata surface c _b,
It may be a vertical flat surface c _c , and its protrusion c
It is needless to say that the bite is not limited to the lower side but may be the upper side or both the upper side and the lower side.

Although the shaft portion 11a of the center wheel & pinion 11 is made of PPS resin containing potassium titanate whiskers in the above-mentioned embodiment, the invention is not limited to this, and a polyetherimide resin containing potassium titanate whiskers may be used. Moreover, although potassium titanate whiskers are used as a reinforcing material for the resin used for the shaft portion 11a and the gear portion 11c, the present invention is not limited to this, and examples thereof include glass fibers, carbon fibers, reduced potassium titanate whiskers, and the like. May be used.

In the above embodiment, the shaft portion 11a is made of PPS resin containing potassium titanate whiskers, and the gear portion 11c is made of 12 nylon resin containing potassium titanate whiskers, so that the slip torque is about 3 to 6 g.cm. Although it was set, it is possible to obtain a slip torque of 2 to 10 g · cm by changing these materials.

Further, in the center wheel & pinion 11 of the above-mentioned embodiment, the shaft portion 11a and the gear portion 11c are integrally molded so as to be slip-rotatable and then immersed in silicone oil. However, the present invention is not limited to this. Of the portion 11a and the gear portion 11c, the first formed primary molded product may be immersed in silicon oil having a dimethylsiloxane structure and annealed. Also, the shaft 1
Molded with resin pellets containing a few percent of silicon-based oil for both 1a and the gear portion 11c,
Only one of them may be molded with resin pellets containing a few percent of silicon-based oil, and need not necessarily be molded with resin pellets containing a few percent of silicon-based oil.

Further, the manufacturing method of the present invention can be applied not only to the second wheel & pinion 11 as described above but also to other gears such as the third wheel & pinion 10, and is not limited to the electronic wrist watch, and can be applied to other pointer type. It can also be widely applied to watches.

[0031]

As described above, according to the method of manufacturing the slip mechanism of the present invention, the primary molded shaft portion is disposed in the gear portion molding die, and the resin is injected into the die. This allows the resin injection gate of the mold to be located on one side in the axial direction of the shaft of the gear and when facing the one side of the mold when the gear is integrally molded on the shaft so as to allow slip rotation. Since the annular protrusion is provided closer to the center than the resin injection gate on the other side, the high temperature resin injected from the resin injection gate does not flow directly into the joining protrusion of the shaft portion.
Since it hits the opposite surface of the mold and goes over the annular protrusion and then flows toward the joining protrusion of the shaft, it takes time to reach the joining protrusion of the shaft and the heat quantity is generated due to the flow resistance. It is possible to reliably prevent the gear portion from being fused and the resin temperature to be lowered and the gear portion to be fused to the shaft portion, and it is possible to manufacture a slip mechanism having an appropriate and stable slip torque.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of an analog movement of an electronic wrist watch using a center wheel and pinion manufactured by a method for manufacturing a slip mechanism of a timepiece according to the invention.

FIG. 2 is an enlarged sectional view of the second wheel & pinion.

FIG. 3 is a diagram showing a method of manufacturing the second wheel & pinion.

FIG. 4 is a view showing a modified example of the center wheel & pinion.

[Explanation of symbols]

 11 Second wheel 11a Shaft part 11b Tube pinion part 11c Gear part 16 Mold 16a Projection part j Recessed part G Resin injection gate

Claims (1)

[Claims] 1. A shaft part having a joining protrusion protruding in a direction perpendicular to the axial direction is molded from synthetic resin, and the joining protrusion is molded into a mold for molding a gear part. A slip mechanism of a timepiece which is arranged so as to be exposed in a space, in which a resin is injected into the space of the mold and the inner peripheral portion of the gear portion is slip-rotatably coupled to the joint protrusion of the shaft portion. The method of manufacturing, wherein the position of the resin injection gate of the mold is provided at one side surface in the axial direction of the gear part, and the resin on the other side surface facing the one side surface of the mold. An annular protrusion that protrudes toward the one side surface is provided closer to the center than the injection gate, and the molten resin injected from the resin injection gate is changed in direction by the annular protrusion toward the joining protrusion. A slipping machine for watches characterized by being made to flow Manufacturing method of structure.