JP2003284281A - Stepping motor and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent axial shift of a lead screw due to spot chips being produced during spot welding a bracket and a case. <P>SOLUTION: The stepping motor comprises a lead screw 3 being fixed with a magnet 2 to the outer circumference at one end thereof, a coil 4 for driving the magnet 2, a case for containing the drive coil 4, and a pivot bearing 7 abutting against the pole teeth of the case 5 and being coupled with the lead screw 3 through a ball 6 wherein a ventilation mechanism 9 is provided at a part of the pivot bearing abutting against the pole teeth of the case. During spot welding the bracket 8 and the case 5, air is jetted from the lead screw 3 side through the ventilation mechanism 9 in order to blow off spot chips to the outside. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor and a manufacturing method thereof, and more particularly to a stepping motor having a structure for supporting an outer circumference of a pivot bearing by a circumference of a motor driving case and a manufacturing method of the stepping motor.

[0002]

2. Description of the Related Art A stepping motor is known which is driven by an input pulse signal and rotates at a constant angle for each pulse. FIG. 5 shows a cross section of a conventionally known stepping motor.

As shown in FIG. 5, the stepping motor 2
1 is equipped with a lead screw 23 having a magnet 22 attached to the outer periphery of one end.
Is a drive coil 2 provided to face the magnet 22.
Driven by 4. The drive coil 24 is housed in the case 25.

The lead screw 23 is used for the ball 2
It is rotatably connected to the pivot bearing 27 via 6. A part of the outer circumference of the pivot bearing 27 is attached to the case 25.
Abuts against the pole tooth portion of the pivot bearing 27, thereby supporting the pivot bearing 27 so as not to fall inside the case 25. The pivot bearing 27 is also supported by a part of the bracket 28. A spring 29 is provided between the bracket 28 and the pivot bearing 27, and the spring 29 biases the pivot bearing 27 toward the lead screw 23. The stepping motor having such a structure has an advantage that it is particularly easy to assemble.

[0005]

The bracket 28 described above is spot-welded and attached to a part of the case 25. In this spot welding process,
Spot debris may occur. The spot dust hinders the movement of the pivot bearing 27 in the thrust direction, which may cause a misalignment of the lead screw 23.

The present invention has been made in view of the above problems, and a stepping motor capable of preventing malfunction due to spot dust that may occur during spot welding of a bracket and a case and manufacturing thereof. The purpose is to provide a method.

[0007]

In order to achieve the above object, a stepping motor according to the present invention includes a lead screw having a magnet attached to the outer periphery at one end, a drive coil for driving the magnet, and a drive coil. In a stepping motor including a case to be housed, a pivot bearing that contacts the pole teeth of the case and is connected to the lead screw through a ball, and a bracket that is spot-welded to the case and supports the pivot bearing, the pivot bearing is , And a ventilation mechanism provided in a portion of the case that abuts the pole teeth. The ventilation mechanism may be a notch cut from the outer circumference of the pivot bearing toward the center, a through hole penetrating the pivot bearing, or a groove provided on the surface of the pivot bearing. When spot-welding the bracket and the case, by ejecting air from the lead screw side to the ventilation mechanism, it is possible to fly the pivot bearing waste to the outside.

In order to achieve the above-mentioned object, in the method of manufacturing a stepping motor according to the present invention, a lead screw having a magnet attached to the outer periphery of one end, a drive coil for driving the magnet, and a drive coil are housed. In the method for manufacturing a stepping motor, the stepping motor is provided with: a case; The method includes a step of providing a ventilation mechanism in the bearing and a step of spot welding the case and the bracket from the lead screw side while injecting air into the ventilation mechanism of the pivot bearing.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A stepping motor and a method of manufacturing the same according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view of a stepping motor 1 shown as an embodiment of the present invention. As shown in FIG. 1, a stepping motor 1 to which the present invention is applied has a lead screw 3 having a magnet 2 attached to the outer periphery of one end.
A plurality of drive coils 4 provided at positions facing the magnet 2 for driving the magnet, a case 5 for housing the drive coil 4, a pole tooth of the case 5, and a lead screw through a ball 6 A pivot bearing 7 connected to the casing 3 and a bracket 8 that is spot-welded to the case 5 and supports the pivot bearing 7 are provided. Further, the pivot bearing 7 is provided with a ventilation notch 9 in a portion of the pivot bearing 7 that comes into contact with the pole teeth of the case 5.

FIG. 2A is a plan view of the pivot bearing 7, and FIG. 2B is a sectional view of the pivot bearing 7 taken along the line XY shown in FIG. Note that FIG.
The shaded portion in (a) indicates the portion that contacts the pole teeth of the case 5. As shown in FIG. 2, the ventilation notch 9 is provided so as to penetrate through a portion of the case 5 that abuts the pole teeth and to be cut from the outer periphery of the pivot bearing 7 toward the center.

In the manufacturing process of the stepping motor 1, the bracket 8 and the case 5 are spot-welded as described above. During this spot welding step, air is jetted from the lead screw 3 side toward the ventilation notch 9 of the pivot bearing 7. As a result, the spot dust generated by the spot welding does not enter the inside of the stepping motor 1 but is blown outside. Therefore,
The movement of the pivot bearing 7 in the thrust direction is hindered by the spot dust, and the problem that the lead screw 3 is misaligned is eliminated.

A first modification of the present invention is shown in FIG. Figure 3
The pivot bearing 10 shown in (1) has a through hole 11 for allowing air to pass therethrough at a position overlapping with a portion contacting the pole teeth. Even if the bracket 8 and the case 5 are spot-welded while injecting air through such a through hole 11,
The same effect as described above can be obtained.

Further, a second modification of the present invention is shown in FIG. The pivot bearing 12 shown in FIG. 4 is provided with a ventilation groove 13 provided on the surface that abuts the pole teeth. Note that FIG.
(B) is X- of the pivot bearing 12 shown in FIG.
The cross section at the Y line is shown. Such a ventilation groove 13
Even if the bracket 8 and the case 5 are spot-welded while injecting air via the, the same effect as described above can be obtained.

[0015]

As described above, in the stepping motor according to the present invention, the lead screw having the magnet attached to the outer periphery at one end, the drive coil for driving the magnet, the case for housing the drive coil, and the pole of the case. It is equipped with a pivot bearing that contacts the teeth and is connected to the lead screw via a ball, and a bracket that is spot-welded to the case and supports the pivot bearing.The pivot bearing is provided at the portion that contacts the pole teeth of the case. Since the ventilation mechanism is provided, the spot dust can be blown to the outside by injecting air from the lead screw side to the ventilation mechanism when spot welding the bracket and the case. As a result, the spot dust prevents the pivot bearing from moving in the thrust direction, and it is possible to prevent defects such as axial misalignment of the lead screw.

The stepping motor manufacturing method according to the present invention includes the step of providing a ventilation mechanism in the pivot bearing, and spot welding the case and the bracket while injecting air from the lead screw side into the ventilation mechanism of the pivot bearing. With this, it is possible to fly the spot dust to the outside, thereby preventing the spot dust from disturbing the movement of the pivot bearing in the thrust direction and preventing the lead screw from being misaligned.

[Brief description of drawings]

FIG. 1 is a sectional view of a stepping motor to which the present invention is applied.

2A and 2B are a plan view and a sectional view of a pivot bearing of the stepping motor shown in FIG.

FIG. 3 is a diagram showing a first modification of the pivot bearing.

FIG. 4 is a diagram showing a second modification of the pivot bearing.

FIG. 5 is a sectional view of a conventional stepping motor.

[Explanation of symbols]

1 stepping motor 2 magnets 3 lead screw 4 drive coil 5 cases 6 balls 7 pivot bearings 8 brackets 9 notches for ventilation

Claims (5)

[Claims] 1. A lead screw having a magnet attached to the outer periphery of one end, a drive coil for driving the magnet, a case for accommodating the drive coil, and a pole tooth of the case. In a stepping motor including a pivot bearing connected to the lead screw and a bracket that is spot-welded to the case and supports the pivot bearing, the pivot bearing is provided in a portion in contact with the pole teeth of the case. A stepping motor having a ventilation mechanism. 2. The stepping motor according to claim 1, wherein the ventilation mechanism is a notch cut from the outer circumference of the pivot bearing toward the center. 3. The stepping motor according to claim 1, wherein the ventilation mechanism is a through hole that penetrates the pivot bearing. 4. The stepping motor according to claim 1, wherein the ventilation mechanism is a groove provided on a surface of the pivot bearing. 5. A lead screw having a magnet attached to the outer periphery of one end, a drive coil for driving the magnet, a case for accommodating the drive coil, a pole tooth of the case, and a ball via a ball. In a method of manufacturing a stepping motor comprising a pivot bearing connected to the lead screw and a bracket that is spot-welded to the case and supports the pivot bearing, a step of providing a ventilation mechanism in the pivot bearing, and a step of providing the lead screw. A stepping motor manufacturing method comprising spot welding the case and the bracket from the side while injecting air into the ventilation mechanism of the pivot bearing.