JPH09155087A - Upper shaft mechanism for sewing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an upper shaft mechanism for sewing machine for domestic and industrial use equipped with a means for reducing the vibration and noise of sewing machine. SOLUTION: Concerning the sewing machine provided with an upper shaft 1 supported through a bearing to a sewing machine frame so as to be rotated, 1st crank 10 fixed at one end of upper shaft 1, balance 3 to be swung while being connected to the 1st crank 10 so as to be turned, 2nd crank 2 connected to one end of 1st crank 10, needle bar crank rod 4 connected to the 2nd crank 2 so as to be turned and needle bar to be reciprocatively moved up and down through the needle bar crank rod 4, the supporting point of balance 3 and the supporting point of needle bar crank rod 4 are arranged at the positions having the phase difference of almost 180 deg. to the axial center of upper shaft 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an upper shaft mechanism of a sewing machine which reduces vibrations and noises that accompany movements of a needle bar and a balance.

[0002]

2. Description of the Related Art Conventionally, as shown in FIGS. 6 and 7, household and industrial sewing machines have one end of an upper shaft 20 rotatably supported by an upper shaft bearing 30 provided in a machine frame. The balance crank 29 is fixed. A toothed pulley (not shown) is fixed to the other end of the upper shaft 20, and is connected to a motor (not shown) as a drive source by a toothed belt. Then, as the motor rotates, the upper shaft 20
Is rotated. A needle bar crank 32 is fixed to the balance crank 29, and a balance 27 having a thread insertion hole 27a for inserting an upper thread is rotatably connected to the needle bar crank 32. A balance support 2 whose one end is rotatably supported by a balance support shaft 31 installed in the machine frame of the sewing machine.
The other end 8 is rotatably connected to the balance 27. Therefore, as the upper shaft 20 rotates, the balance 27
The thread insertion hole 27a is rocked.

Further, one end 25 of the needle bar crank rod 24 is rotatably connected to the other end of the needle bar crank 32. The angle A between the fulcrum 19 of the balance 27 and the fulcrum 18 of the needle bar crank rod 24 as shown in FIG.
It is arranged at an angle of about 30 ° with respect to the axis C ₁ of. The other end of the crank rod 24 is rotatably connected to the needle bar 22. The needle bar 22 is vertically movably supported by a bearing 33 provided on a needle bar base 26 supported by the machine frame. At the lower end of the needle bar 22,
A needle 21 is pierced through the material to be sewn for sewing. A needle drop hole (not shown) through which the needle 21 penetrates is formed on the sewing machine bed surface, and a needle plate (not shown) on which the work cloth is placed is arranged. Then, the work cloth is placed on the needle plate, and the motor 27 is driven to rotate the upper shaft 20, whereby the balance 27 and the needle 21 perform their respective operations to sew the work cloth.

[0004]

However, one of the main causes of vibrations of the domestic and industrial sewing machines is the inertial force generated by the swing motion of the balance 27 and the vertical reciprocating motion of the needle bar 22. . The fulcrum 18 of the needle bar crank rod 24 and the fulcrum 19 of the balance 27 are arranged at a position of about 30 ° with respect to the upper shaft, but the respective fulcrums 18, 19 are in substantially the same phase and rotate around the upper shaft 20. Upper shaft bearing 3 to rotate in
The bearing load applied to 0 was large, which caused vibration and noise. The balance crank 29 is provided with an eccentric mass in order to cancel out the inertial force generated from the balance and needle bar mechanism, but this is not sufficient to eliminate vibration and noise, and conversely, the weight of the balance crank 29 is reduced by the motor. Had become a big load.

FIG. 8 shows the bearing load acting on the upper shaft bearing 30 when the needle bar mechanism or the balance mechanism is operated independently. The chain line indicates the bearing load generated by the needle bar mechanism, and the broken line indicates the bearing load generated by the balance mechanism. As shown in this figure, the load applied to the bearing is in phase with the needle bar mechanism and the balance mechanism, and the bearing load indicated by the solid line is the bearing 30.
And generated a large excitation force. For this reason, vibration and noise of the sewing machine were also increased.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to obtain an upper shaft mechanism for domestic and industrial sewing machines equipped with means capable of reducing vibration and noise of the sewing machine. .

[0007]

In order to achieve this object, in the upper shaft mechanism of a sewing machine according to claim 1, an upper shaft rotatably supported by a machine frame of a sewing machine through a bearing, and the upper shaft. A first crank fixed to one end of the first crank, a balance rotatably connected to the first crank and swinging, a second crank connected to one end of the first crank, and a second crank In a sewing machine including a needle bar crank rod rotatably connected to two cranks and a needle bar vertically reciprocating via the needle bar crank rod, a sewing machine is rotatably connected to the first crank. And the fulcrum of the needle bar crank rod rotatably connected to the second crank is arranged at a position having a phase difference of about 180 ° with respect to the axis of the upper shaft. It is characterized by

With such a structure, the bearing load generated by the needle bar mechanism and the bearing load generated by the balance mechanism have substantially opposite phases, so that the load on the bearing is greatly reduced as a whole. Therefore, the excitation force applied to the machine frame of the sewing machine is reduced, and the vibration that has been conventionally generated can be significantly reduced and the noise can be reduced.

Further, in the sewing machine having the above-mentioned structure, it is not necessary to use the balance crank as a weight for balancing as in the conventional case, so that an eccentric mass portion is not required, so that the weight can be reduced and the motor of the motor can be achieved. It also saves energy because it requires less driving torque.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a mechanical structure of a main part of a sewing machine to which the present invention is applied.
Upper shaft bearings 12a and 12b are provided in the machine frame, and the upper shaft 1 is rotatably supported by the upper shaft bearings 12a and 12b. One end of the first crank 10 is fixed to one end of the upper shaft 1, and a pulley (not shown) is fixed to the other end of the upper shaft 1. The second crank 2 is connected to the other end of the first crank 10. As the motor (not shown), which is a drive source, rotates, the power thereof is transmitted to the pulley, so that the upper shaft 1, the first crank 10, and the second crank 2 are connected to the upper shaft 1 shown in FIG. It is designed to rotate around the axis C ₀ .

A balance 3 having a thread insertion hole 3a for inserting an upper thread is rotatably connected to the first crank 10. A balance support 7 having one end rotatably supported by a balance support shaft 6 installed on the machine frame is rotatably connected to the balance 3 at the other end.
The other end of the needle bar crank rod 4 is rotatably connected to the needle bar 5. The needle bar 5 is vertically movably supported by a bearing 13 provided on a needle bar base supported by the machine frame. At the lower end of the needle bar 5, a needle 14 for penetrating a sewing object and performing sewing is supported. As shown in FIG. 2, the fulcrum 8 of the needle bar crank rod 4 rotatably connected to the second crank 2 is approximately 180 with respect to the fulcrum 9 of the balance 3 and the axis C ₀ of the upper shaft 1. It is placed at a position with a phase difference of °. Therefore, the fulcrums 8 and 9 rotate about the axis C ₀ of the upper shaft 1 in substantially opposite phases.

As shown in FIG. 5, the bearing load applied to the sewing machine having the above-described structure causes the balance mechanism and the needle bar mechanism to move in opposite phases to each other, so that the inertial forces generated by the respective mechanisms cancel each other out. The number of parts is increased, and the bearing load applied to the bearing 12a is significantly reduced as compared with the conventional sewing machine shown in FIG. Further, in the sewing machine having the above configuration,
Although the balance crank is used as a weight to balance the load as in the conventional case, the eccentric mass portion is not required and the weight can be reduced. Along with this, the driving torque of the motor can be reduced and energy can be saved.

Incidentally, the movement of the tip of the balance is opposite to that of the conventional sewing machine, but this is similar to the conventional sewing machine by passing the upper thread through the thread guide 35 and the thread guide 36 before and after the balance as shown in FIG. Tighten the upper thread to keep the tension of the upper thread,
It can be sewn.

[0015]

As is apparent from the above description, in the upper shaft mechanism of the sewing machine according to the first aspect, the balance which is rotatably connected to the first crank and the second crank are rotatable. Since the fulcrum of the needle bar crank rod that is operably connected is arranged at a position having a phase difference of approximately 180 ° with respect to the axis of the upper shaft, the bearing load generated by the needle bar mechanism and the balance are Since the bearing load generated in the mechanism is in the opposite phase, the bearing load is significantly reduced as a whole. For this reason, the vibration force applied to the machine frame of the sewing machine is reduced, and the vibration that has been conventionally generated can be reduced and the noise can be reduced.

Further, since it is not necessary to make the balance crank act as a weight for balancing as in the conventional case, the portion of the eccentric mass is unnecessary and the weight can be reduced. Furthermore, since the driving torque of the motor can be small, energy can be saved.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of a mechanism of a sewing machine to which the present invention is applied.

FIG. 2 is a view showing a needle bar and a balance mechanism of the sewing machine of the present invention.

FIG. 3 is a view showing a needle bar and a balance mechanism of a conventional sewing machine.

FIG. 4 is an example of how to thread the upper thread of a sewing machine to which the present invention is applied.

FIG. 5 is a diagram showing bearing loads generated by the needle bar mechanism and the balance mechanism of the sewing machine of the present invention.

FIG. 6 is a view showing a mechanism of a conventional sewing machine.

FIG. 7 is an exploded view of a mechanism of a conventional sewing machine.

FIG. 8 is a diagram showing a bearing load generated by a needle bar mechanism and a balance mechanism of a conventional sewing machine.

[Explanation of symbols]

 1 Upper shaft 2 Second crank 3 Balance 4 Needle bar crank rod 5 Needle bar 6 Balance support shaft 7 Balance support 8 Needle bar crank rod fulcrum 9 Balance fulcrum 10 First crank 12 Upper shaft bearing

Claims (1)

[Claims] 1. An upper shaft rotatably supported by a machine frame via bearings, a first crank fixed to one end of the upper shaft, and a rotatably connected to the first crank. Via a swinging balance, a second crank connected to one end of the first crank, a needle bar crank rod rotatably connected to the second crank, and the needle bar crank rod. And a needle bar crank rod rotatably connected to the second crank, wherein the balance is rotatably connected to the first crank and a needle bar crank rod rotatably connected to the second crank. And a fulcrum of the sewing machine are arranged at a position having a phase difference of about 180 ° with respect to the axis of the upper shaft.