JPH07136367A - Sewing machine - Google Patents

Abstract

PURPOSE:To reduce vibration and noise at the time of sewing by negating the inertial force in the vertical direction generated by the reciprocating motion of a needle bar. CONSTITUTION:A main spindle 1 is rotatably supported by bearings 2a, 2b, and one end of it is interlocked with a motor via a pulley 3 and a belt. A grooved cam 4 is provided at the other end of the main spindle 1, and it is rotated together with the main spindle 1. A slider 5 is connected to the grooved cam 4 slidably along the groove, the intersection part of a forked link 6 is connected to the slider 5, and it is reciprocated in the main spindle direction together with the slider 5'. The forked link 6 is connected to a balancer 7 at one end and to a needle bar 8 at the other end, and the balancer 7 and the needle bar 8 can be vertically moved along a guide 10 in opposite phases to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sewing machine in which vibration generated by the vertical movement of a needle bar is reduced.

[0002]

2. Description of the Related Art Conventionally, in this type of sewing machine, FIG.
As shown in FIG. 2, in order to cancel out the inertial force generated with the vertical movement of the needle bar 100, the centrifugal force of the needle bar crank 102, whose center of gravity is located eccentric from the axis of the main shaft 104, is known. Has been. This centrifugal force works only in the vertical direction when the needle bar is at the uppermost point or the lowermost point and cancels out the inertial force of the needle bar, but also works horizontally when the needle bar 100 is in the middle. Therefore, even if the eccentric mass of the needle bar crank 102 is determined so that the vertical and horizontal exciting forces acting on the sewing machine body are minimized, the main shaft 104
The vibration force that acts on the sewing machine frame 106 that supports the machine does not become sufficiently small.

Further, as a mechanism for reducing the vibrating force acting on the sewing machine main body to prevent the vibration, there is a practical use method, Sho 60-19277.
The vibration prevention mechanism described in Japanese Patent No. 4 is known. In the vibration preventing mechanism described in this publication, as shown in FIG. 4, a main shaft 104 is rotatably supported by a sewing machine frame 106, and a needle bar crank 102 is attached to the main shaft 104.
It is fixed so as to rotate together with 04. The connecting rod 108 is attached to the needle bar crank 102.
Is rotatably supported, and further, the needle bar 100 is supported at the tip of the connecting rod 108 so as to be vertically movable. At this time, the center of gravity G of the needle bar crank 102
1 is eccentric from the axis C1 of the main shaft 104, and the needle bar 10
Center of gravity G of needle bar crank 102 when 0 is located at the highest point
1 is fixed so as to be located directly below the axis C1.

Further, as the main shaft 104 rotates, the balancer shaft 110 rotates through the gears 112a and 112b having the same gear ratio and meshed with each other, and the balancer shaft 110 rotates.
The balancer 114 fixed to the shaft also rotates. The center of gravity G4 of the balancer 114 is fixed so as to be located immediately below the axis C4 of the balancer shaft 110 when the needle bar 100 is located at the uppermost point.

Here, G1 is the center of gravity of the needle bar crank 102, G2 is the combined center of gravity of the needle bar 100, the needle bar holder 101, and the connecting rod 108.
Of the main shaft 10 from the point of supporting the connecting rod 108 of the needle bar crank 102, the mass of the main shaft 10 is M1, the total mass of the needle bar and the like is M2, the distance between the shaft centers C1 and G1 of the main shaft 104 is L1.
4 is L2, the distance between the supporting points of the connecting rod 108 is L3, and the crank ratio is λ (= L
2 / L3). In addition, the mass of the balancer 114 is M
4. Let L4 be the distance between the axis C4 of the balancer shaft 110 and the center of gravity G4 of the balancer.

When the main shaft 104 of the sewing machine having the above structure rotates at the rotational angular velocity ω, the sewing machine frame 106
Horizontal and vertical exciting force Fx, Fy acting on the sewing machine body via a is the case of the lambda is very small, negligible lambda ³ or more components can be expressed by the following equation.

[0007]

[Equation 1]

[0008]

[Equation 2]

Here, M4 × L4 = M1 × L1, M2 ×
If L2 = 2M1 × L1 is set, the following Expressions 1 and 2 are obtained.

[0010]

[Equation 3]

[0011]

[Equation 4]

As described above, the exciting force can be reduced as compared with the case where the balancer 114 is not used, and the smaller the crank ratio λ, the smaller the exciting force.

[0013]

However, since L2 is determined by the stroke of the needle bar and L3 cannot be made larger than the size constraint of the sewing machine frame, the crank ratio λ
Cannot be made too small, and usually takes a value of 1/4 to 1/2.
Therefore, the component of λ ³ or more cannot be ignored and the vertical excitation force Fy cannot be completely canceled. Further, since the balancer 114 is driven by gear transmission, gear noise is newly generated.

The present invention has been made in order to solve the above-mentioned problems, and its purpose is to cancel the vertical inertial force generated by the reciprocating motion of the needle bar, thereby reducing the vibration and suppressing the vibration. To provide a sewing machine.

[0015]

In order to achieve this object, a sewing machine according to the present invention comprises a groove cam at one end of a main shaft rotatably supported, and a slider that reciprocates in the main axis direction as the groove cam rotates. , A bifurcated link holding the needle bar at one end and the balancer at the other end so that the direction of the reciprocating motion of the slider is changed and the needle bar and the balancer move up and down in opposite phases.

A sewing machine according to a second aspect of the present invention includes a balancer having a weight such that the inertial force has the same absolute value as the inertial force generated by the movement of the needle bar.

Further, in the sewing machine according to the third aspect of the invention, the sewing machine frame is provided with a damping material for damping the exciting force in the main axis direction.

[0018]

In the sewing machine of the present invention having the above structure,
When the groove cam provided at one end of the main shaft rotates, the slider reciprocates in the main shaft direction. When the intersection of the forked link reciprocates according to the slider, the two ends of the forked link move up and down. Further, the needle bar at one end and the balancer at the other end of the bifurcated link move up and down in opposite phases with the same absolute value of each inertial force. Further, the damping material provided in the machine frame of the sewing machine acts so as to damp the exciting force in the main axis direction.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

The sewing machine of the present invention has a main shaft 1 as shown in FIG.
Is rotatably supported by bearings 2a and 2b, and one end thereof is linked with an electric motor (not shown) via a pulley 3 and a belt (not shown). A grooved cam 4 is provided at the other end of the main shaft 1 and rotates together with the main shaft 1. A slider 5 is connected to the groove of the groove cam 4 so as to be movable along the groove. Further, the slider 5 is connected to the intersection of the bifurcated link 6 and reciprocates in the main axis direction together with the slider 5. A balancer 7 is connected to one end of the two ends of the bifurcated link 6, and a needle bar 8 is connected to the other end of the bifurcated link 6. There is. The guide 10 is vertically fixed to the sewing machine frame.

The specific operation and force balance of each mechanical component will be described with reference to FIGS. 1 and 2. When the main shaft 1 rotates, the groove cam 4 also rotates accordingly. At this time, slider 5
Reciprocates in the main axis direction along the slider guide 12. The reciprocating motion of the slider 5 in the main axis direction is a bifurcated link 6.
Is converted into a vertical reciprocating motion. That is,
The balancer 7 and the needle bar 8 connected to the two ends of the bifurcated link 6 reciprocate in the vertical direction in mutually opposite phases. The slider guide 12 is horizontally fixed to the sewing machine frame.

As shown in FIG. 2, the force acting on the bifurcated link 6 is an inertial force F _y1 generated by the vertical reciprocating motion of the balancer 7 at point A, and the vertical reciprocation of the needle bar 8 and needle 9 at point B. The inertial force F _y2 generated by the motion and the inertial forces F _x1 and F _x2 generated by the reciprocating motion of the slider 5 and the bifurcated link 6 in the principal axis direction act on the point O, respectively. here,
The mass of the balancer 7 is adjusted so that the inertial force F _y1 by the balancer 7 has the same absolute value as the inertial force F _y2 by the needle bar 8 and the needle 9. The directions in which the inertial forces F _y1 and F _y2 act are opposite because the balancer 7 and the needle bar 8 move in opposite phases, and act so as to cancel each other out.

On the other hand, the inertial forces F _x1 , F in the main axis direction
_{Since x2} acts in the same direction, they cannot cancel each other and remain. As a result, when the main shaft rotates and the needle bar 8 reciprocates vertically, the only bearing load acting on the bearings 2a and 2b supporting the main shaft 1 is the inertial forces F _x1 and F _{x2 in the} main shaft direction, and the vertical force. Does not work. However, the inertial force in the main shaft direction passes from the main shaft 1 through the damping members 11a and 11b to the bearing 2
Since it is transmitted to a and 2b, the vibration force acting on the bearing can be suppressed as much as possible.

Since the vertical inertial force generated by the reciprocating motion of the needle bar is completely canceled, the vibration of the sewing machine is prevented. Along with this, it is possible to perform accurate sewing on the workpiece and reduce noise due to vibration.

[0025]

As is apparent from the above description, in the sewing machine of the present invention, the balancer moves in a phase opposite to that of the needle bar to completely eliminate the vertical inertial force generated by the reciprocating motion of the needle bar. Since it can be canceled, the vibration of the sewing machine is reduced, which enables quiet and accurate sewing.

[Brief description of drawings]

FIG. 1 is an assembly view of a spindle / needle bar mechanism of the present invention.

FIG. 2 is a diagram showing a force acting on the link mechanism of the present invention.

FIG. 3 is an upper shaft mechanism diagram of a conventional sewing machine.

FIG. 4 is an upper shaft mechanism diagram of a conventional sewing machine.

[Explanation of symbols]

 1 spindle 2 bearing 4 groove cam 5 slider 6 bifurcated link 7 balancer 8 needle bar 10 guide 11 damping material

Claims (3)

[Claims] 1. A sewing machine configured such that a needle moves up and down through a work cloth arranged on a needle plate by rotation of a spindle rotatably supported by a sewing machine frame, wherein a groove is formed at one end of the spindle. A slider provided with a cam, which reciprocates in the main axis direction in accordance with the rotation of the groove cam, a bifurcated link for converting the reciprocating direction of the slider, a needle bar held at one end of the bifurcated link, and a balancer at the other end. A sewing machine which is held, and the needle bar and the balancer move up and down in opposite phases. 2. The sewing machine according to claim 1, wherein the weight of the balancer is determined so that the inertial force has the same absolute value as the inertial force generated by the movement of the needle bar. 3. The sewing machine according to claim 1, wherein the sewing machine frame holds a damping material for damping a vibration force in a main axis direction.