JPH06327876A - Sewing machine - Google Patents

Abstract

PURPOSE:To provide a sewing machine incorporating a means for reducing noise generated at a cover and caused by a motion of a mechanism part. CONSTITUTION:An lead plate 44 is inserted in a part of a front cover 32 for a sewing machine, corresponding to the loop of a natural vibration, so as to increase the weight of the part, and accordingly, the vibration speed of the front cover 32 is restrained even though vibration occurs at a frame due to the motion of a mechanism part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sewing machine, and more particularly to a sewing machine having a cover.

[0002]

2. Description of the Related Art Conventionally, a sewing machine has a mechanism as shown in FIG. In detail, at least one motor 1 as a drive source for driving a needle bar 28 described later and others.
The timing belt 12 is stretched between the drive shaft of the motor 10 and the upper shaft pulley 14 described later. Further, the upper shaft pulley 14 is fixed to the right end of the upper shaft 16 and can be rotated together with the upper shaft 16 by the driving force transmitted from the timing belt 12.

Further, the upper shaft 16 is rotatably attached to a frame 30 shown in FIG.
A balance crank 18 is fixed to the left end of 6, and one end of a balance 20 is rotatably attached to the balance crank 18. Further, a needle bar crank 22 is fixed to the balance crank 18, and the needle bar crank 2
One end of a connecting rod 24 is rotatably attached to 2. Also, the connecting rod 2
A needle bar holder 26 is rotatably attached to the other end of the needle bar 4, and a needle bar 28 is fixed to the needle bar holder 26.

With the above structure, the rotation of the motor 10 is generated by the transmission belt 12, the upper pulley 14, the upper shaft 16,
It is transmitted to the needle bar 28 via the balance crank 18, the needle bar crank 22, the connecting rod 24, and the needle bar holder 26, whereby the needle bar 28 reciprocates in the vertical direction. Further, the rotation of the upper shaft 16 is transmitted to the balance 20 via the balance crank 18, and the balance 20 reciprocates.

The above-mentioned mechanism is supported by the frame 30 shown in FIG. 4, and the front cover 32 and the left cover 3 are provided.
4, the right cover 38 is covered, and at least a part of these covers is connected to the frame 30 by fastening parts such as screws.
Was fixed to.

[0006]

However, in the conventional sewing machine as described above, vibration is generated by the reciprocating motion of the needle bar and the balance, the rotation of the motor, etc., and the vibration is transmitted to the cover via the frame, The vibration of the cover vibrates the surrounding air to generate noise.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a sewing machine having means for reducing noise generated by vibration of the cover.

[0008]

To achieve this object, in the sewing machine of the present invention, the weight of the antinode portion of the natural vibration mode of the cover is made heavier than the other portions.

[0009]

In the sewing machine of the present invention having the above-mentioned structure, even if vibrations due to the reciprocating motion of the needle bar and the balance, the rotation of the motor, etc. are transmitted to the cover through the frame, the weight of the part where the vibration amplitude is large The vibration velocity becomes small because the weight is made heavy. Thereby, the noise generated by the cover vibrating the surrounding air can be suppressed.

[0010]

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

Since the mechanism of the sewing machine of this embodiment is the same as that of the conventional example, its detailed description will be omitted. The structure of the cover, which is the main part of this embodiment, will be described with reference to FIGS. 1 and 2.

In general, a structure has several natural frequencies, and when it is given a vibration close to those natural frequencies, it vibrates extremely greatly. This form of vibration is called a natural vibration mode, where very large vibration is called an antinode, and where it is hardly displaced is called a node. In order to obtain the natural frequency and natural vibration mode of a structure, an experimental modal analysis that measures how the vibration propagates (transfer function) when the structure is vibrated or a finite element model created on a computer is used. A theoretical modal analysis is used to perform eigenvalue analysis.

For example, it is assumed that the front cover 32 has a natural vibration mode as shown in FIG. 2 at a certain natural frequency by an experimental modal analysis or a theoretical modal analysis. Here, the wavy line in the drawing represents the state before deformation, and the solid line represents the deformed state during vibration. In this natural vibration mode, there is a portion (antinode) having a large displacement, such as a portion indicated by a circle in the figure.

As shown in FIG. 1, a lead plate 44 is insert-molded in the vicinity of the belly of the front cover 32 which is fixed to the frame 30 of the sewing machine of this embodiment by fastening components such as screws. Only the part is heavy.

The number of rotations of the upper shaft 16 and the number of rotations of the motor 10,
And the integral multiple thereof is close to the natural frequency of the front cover 32, this natural vibration mode is excited and vibration as shown in FIG. 2 is generated. However, in the above-described sewing machine having the front cover 32, the lead plate is inserted in a portion where the vibration amplitude is large to make the weight heavy, so that the vibration speed becomes small, and therefore the front cover 32 is surrounded by the surrounding air. The noise generated by vibrating the can be suppressed.

In addition to the front cover 32, the left cover 3
Also in the case of 4, the right cover 38, the lower cover 40, and the bottom cover 42, the same effect can be obtained by similarly increasing the weight of the antinode portion of the vibration based on each natural vibration mode. Further, although the lead plate is insert-molded to increase the weight in the present embodiment, an iron plate or a zinc alloy may be used, and instead of insert-molding, it may be attached by screwing, bonding, or the like.

[0017]

As is apparent from the above description, in the sewing machine of the present invention, the weight of the antinode portion of the natural vibration mode of the cover is made heavier than other portions, so that the noise generated by the vibration of the cover is increased. Can be suppressed.

[Brief description of drawings]

FIG. 1 is a perspective view showing a cover of a sewing machine of the present invention.

FIG. 2 is a diagram showing a natural vibration mode of a cover.

FIG. 3 is a perspective view showing a mechanism of a conventional sewing machine.

FIG. 4 is an exploded perspective view showing a frame and a cover of a conventional sewing machine.

[Explanation of symbols]

 32 front cover 44 lead plate

Claims (1)

[Claims] 1. A sewing machine having a cover that is fastened to a sewing machine frame, wherein a weight of an antinode portion of the natural vibration mode of the cover is
Sewing machine characterized by being heavier than other parts.