JPH08266769A - Sewing machine - Google Patents

Abstract

PURPOSE: To reduce the vibration in the main shaft direction of a sewing machine, in a half turn hook sewing machine shaking a shuttle body using a rack and a pinion, by providing a balance wt. so as to negate the inertial force caused by the riciprocal movement of a lever and the rack. CONSTITUTION: In a sewing machine, a grooved cam 3 is rotated along with the rotation of a main shaft 1 and the lever 5 connected to the groove of the grooved cam 3 is subjected to circular arc motion. A rack 7 is reciprocally moved in an almost main shaft direction according to the circular arc motion of the lever 5 and a balance wt. 15 is attached to the lever 5 to be subjected to circular motion along with the lever 5. The mass and attaching position of the balance wt. 15 are determined so as to negate the inertial force caused by the reciporcal movement of the lever 5 and the rack 7.

Description

Detailed Description of the Invention

[0001]

[Industrial field of application] A pinion that is pivotally supported to swing the hook, a rack that meshes with the pinion and reciprocates left and right, and a rack that is pivotally connected to the rack and that swings around a support point. A sewing machine having a lever that is moved.

[0002]

2. Description of the Related Art Conventionally, a sewing machine of this type has been used as a sewing machine.
A half-turn hook sewing machine described in Japanese Patent Publication No. 67681 is known. In the sewing machine described in this publication, as shown in FIG. 4, a pinion 21 fixed to a driver for driving the inner hook is provided.
A rack 23 that meshes with the pinion 21 and swings the pinion 21, one end rotatably coupled to the rack 23, an intermediate portion rotatably supported by the sewing machine frame, and the other end in the cam groove 25a. A lever 27 connected to the groove cam 25 is provided so as to be movable in the axial direction of the main shaft 26. When the groove cam 25 rotates together with the main shaft 26, the inner hook reciprocally rotates due to the reciprocating motion of the lever 27 and the rack 23. In designing the components that drive the inner pot such as the rack 23 and the lever 27, the rotation angle of the inner pot,
The dimensions of each component have been determined in consideration of mechanical matters such as reciprocating motion of other components.

[0003]

However, when the main shaft 26 is rotated by the above-described sewing machine, the force F ₁ acting on the sewing machine main body through the sewing machine frame is represented by the following equation.

[0004]

[Equation 1]

Here, M ₁ is the mass of the lever 27, M ₂ is the mass of the rack 23, L ₁ is the distance from the support point A to the center of gravity G ₁ of the lever 27, and L ₂ is the rack 23 from the support point A. The distance to the connection point C of the lever 27, and θ are swing angles.
The rack 23 that is rotatably connected to the lever 27 and horizontally reciprocates to the left and right is considered to be a concentrated substance attached to the connection portion with the lever 27, so the distance L ₂ is from the support point A to the center of gravity G of the rack 23. Corresponds to a distance of up to ₂ .

When the condition of "M ₁ × L ₁ = M ₂ × L ₂ " is satisfied, the inertial forces due to the reciprocating motions of the rack 23 and the lever 27 cancel each other out. When designing the components to be driven, if such inertial force is not taken into consideration and only the above-mentioned mechanical matters are taken into consideration, the force F ₁ described above causes vibration and noise accompanying the rotation of the main shaft 26. Was occurring.

Further, setting the mass and the position of the center of gravity of these components so as to reduce the inertial force associated with the reciprocating motion of the components for driving the inner hook lowers the degree of freedom in designing those components. There was a problem.

[0008] Claims 1 and 2 of the present invention have been made to solve the above-mentioned problems, and an object thereof is to provide a low-vibration and quiet sewing machine.

Further, a third aspect of the present invention is to provide a sewing machine in which the degree of freedom of components for driving the shuttle is maintained when the sewing machine is designed to have a low vibration.

[0010]

In order to achieve this object, a sewing machine according to claim 1 of the present invention provides a product of a distance from a center of gravity of a lever to a support point of the lever and a mass of the lever and a rack. Of the product of the distance from the center of gravity to the support point of the lever and the mass of the rack, the counterweight that is provided on the smaller stacking side with the support point as the boundary is the center of gravity of the counterweight. The product of the distance to the support point of the lever and the mass of the counterweight is the product of the distance from the center of gravity of the lever to the support point of the lever and the mass of the lever and the center of gravity of the rack to the support point of the lever. It is arranged so that it is less than twice the difference between the product of the distance and the mass of the rack.

According to a second aspect of the present invention, in the sewing machine, the product of the distance from the center of gravity of the counterweight to the support point of the lever and the mass of the counterweight is the center of gravity of the lever. To the support point of the lever and the mass of the lever, and the product of the product and the distance from the center of gravity of the rack to the support point of the lever It is placed on the side.

Further, in the sewing machine according to the third aspect, a counterweight is retrofitted on the smaller stacking side of the support points.

[0013]

According to the sewing machine of the first aspect of the present invention having the above-mentioned structure, the counterbalance weight has a product of the distance from the center of gravity of the lever to the support point of the lever and the mass of the lever, and the center of gravity of the rack. Of the product of the distance from the point to the support point of the lever and the mass of the rack, it is provided on the smaller product side with the support point as the boundary, and from the center of gravity of the counterweight to the support point of the lever. The product of the distance and the mass of the counterweight is the product of the distance from the center of gravity of the lever to the support point of the lever and the mass of the lever, the distance from the center of gravity of the rack to the support point of the lever, and the mass of the rack. Is less than twice the difference between the product and the product, and the difference in opposing inertial forces in the directions associated with the drive of the shuttle is reduced as compared with the case where no counterweight is used.

According to a second aspect of the present invention, the product of the distance from the center of gravity of the counterweight to the support point of the lever and the mass of the counterweight is the center of gravity of the lever to the support point of the lever. The product of the distance to the lever mass and the product of the distance from the rack center of gravity to the lever support point and the rack mass is equal to the difference between Since they are provided on the side, the opposing inertial forces in the directions associated with the drive of the shuttle are equal to each other.

According to the sewing machine of the third aspect, the counterweight is attached after the lever and the rack are manufactured.

[0016]

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

As shown in FIG. 1, in the sewing machine of the present invention, the main shaft 1 is rotatably supported by a bearing 17, and one end of the main shaft 1 is connected to a motor (not shown) via a pulley 19 and a belt (not shown).
It is connected to the. A groove cam 3 is fixed to the main shaft 1 and rotates together with the main shaft 1. The lever 5 is provided with a counterweight 15, and one end of the lever 5 is connected to the groove of the groove cam 3 so that it can move in an arc along the groove.

The lever 5 is rotatably connected to an arm bed (not shown) at a supporting point A, and the upper side of the lever 5 bordering the supporting point A is shorter than the lower side of the lever 5. . Further, the other end of the lever 5 is rotatably connected to the rack 7. Driver 1 for driving the inner hook 9
1 is rotatably connected to the arm bed, and the pinion 13 is fixed to the driver 11. The rack 7
Engages with the pinion 13.

Next, the specific operation of each component will be described.

When the main shaft 1 rotates, the groove cam 3 also rotates accordingly, and the lever 5 makes an arc motion along the groove of the groove cam 3 about the support point A. The amount of movement of one end of the lever 5 in the main axis direction caused by the rotation of the groove cam 3 depends on the ratio of the lengths of the lever 5 with the support point A as a boundary (the upper side of the lever 5: the lower side of the lever 5). Is amplified. With the circular motion of the lever 5, the rack 7 reciprocates substantially parallel to the axial direction of the main shaft 1, and the pinion 13
Is oscillated, and the driver 11 oscillates together with the inner hook 9. In this way, the upper side (one stacking side) of the lever 5 with the support point A as a boundary is opposite to the lower side of the lever 5 and the rack 7 (other stacking side) with the support point A as a boundary. A oscillating motion is performed in the directions, and inertial forces that are opposite to each other are generated.

Next, the lever 5 and the rack 7 are components which are designed by mechanical matters without considering inertial force as in the conventional case, and the distance from the center of gravity G ₁ of the lever 5 to the support point A of the lever 5 The product of L ₁ and the mass M ₁ of the lever 5 is smaller than the product of the distance L ₂ from the center of gravity G _{2 of the} rack 7 to the support point A of the lever 5 and the mass M _{2 of the} rack 7, and An adhesive is used to attach a counterweight 15 for canceling inertial force to the parts,
The force balance will be described in the case of welding, caulking, or retrofitting with a bolt or the like.

When the main shaft 1 of the sewing machine rotates, the lever 5
The force F ₂ acting on the main body of the sewing machine via the support point of is the mass of the counterweight 15 as M ₃ , and the distance from the support point A to the center of gravity G ₃ of the counterweight L ₃ as L _3. It is represented by.

[0023]

[Equation 2]

In this embodiment, "M ₁ × L ₁ + M ₃ × L ₃
= M ₂ × L ₂ ”, the mass M ₃ and the distance L ₃ are determined. That is, the center of gravity G3 of the counterweight 15 To the support point A of the lever from L3 And the counterweight 15 mass M3 The product of the are from the center of gravity G ₂ of the product and the rack 7 of the mass M ₁ of length L ₁ and the lever 5 from the center-of-gravity point G ₁ of the lever 5 to the supporting point A of the lever to the support point A of the lever 5 The difference between the distance L ₂ and the product of the mass M _{2 of the} rack 7 is made equal. For example, when the fixing position of the counterweight 15 is determined in relation to other parts, the mass M ₃ is set from the distance L ₃ , and conversely, the size of the counterweight, that is, the mass M.
_{If 3} is determined because of other parts, the mass M ₃
Set a distance L ₃ from.

Therefore, since the conditions of the above equations are satisfied, the mutually opposing inertial forces cancel each other out, and the axial force of the main shaft 1 acting on the sewing machine main body is zero. Therefore, the vibration of the sewing machine is prevented, and it becomes possible to sew the workpiece accurately. Further, the lever 5 and the rack 7 are obtained by retrofitting the conventionally designed parts with the counterweight 15 according to the formula in the above-described embodiment. Therefore, when designing the components that drive the inner hook 9, the degree of freedom in designing those components can be maintained as usual. In addition, if the method of retrofitting the counterweight 15 is used in this manner, it is possible to reduce the vibration of the sewing machine already produced.

The present invention is not limited to the above-mentioned embodiments, and various modifications can be made without departing from the spirit of the invention.

In the above embodiment, the product of the distance L ₁ from the center of gravity G ₁ of the lever 5 to the support point A of the lever 5 and the mass M _{1 of the} lever 5 is the center of gravity G of the rack 7. since the ₂ smaller than the product of the mass M ₂ of the distance L ₂ between the rack 7 to support points a of the lever 5, the balance weight 15
Is arranged on the upper side of the lever 5 with the support point A as a boundary, that is, on the side swinging in the opposite direction to the rack 7. However, when the magnitude relation of the product is opposite, the counterweight is 15 may be arranged on the underside of the lever 5 that swings in the same direction as the rack 7 or on the rack 7 (see FIG. 3).

In the above-described embodiment, the counterweight 15 is attached later, but from the design stage of the components for driving the inner hook 9, the lever 5 or the rack 7 is considered in consideration of the formula of this embodiment. The counterweight 15 may be integrally formed. For example, as a result of designing each part by considering only mechanical matters, M
_{When 1} × L ₁ > M ₂ × L ₂ , the lower side of the lever 5 (the portion that swings in the same direction as the rack 7) or the shape of the rack 7 with the support point A as a boundary, The design may be changed again so that Expression (1) is satisfied. On the contrary, when M ₁ × L ₁ <M ₂ × L ₂ is calculated, the supporting point A
The shape of the upper side of the lever 5 (the portion that swings in the direction opposite to the rack 7) and the like at the boundary may be modified so that the expression (1) is satisfied.

Further, in the above-described embodiment, the counterweight 15 is arranged so that the sum of the inertial forces in the opposite directions becomes zero. However, from the center of gravity G ₁ of the lever 5 to the lever. from the center of gravity G ₂ of the product and the rack 7 and the distance L ₁ to the support point a and the mass M ₁ of the lever 5 and the distance L ₂ to the supporting point a of the lever 5 and the mass M ₂ of the rack 7 In the product, the counterweight 15 provided on the smaller product side with the support point A as a boundary is provided from the center of gravity G _{3 of the} counterweight 15 to the support point A of the lever 5. Distance L ₃ and the counterweight 15
Of the product of the mass M ₃ is, the lever 5 of the product and the lever from the center of gravity G ₂ of the rack 7 and the distance L ₁ from the center of gravity to the supporting point A of the lever 5 and the mass M ₁ of the lever 5 5 is arranged so as to be less than twice the difference between the distance L ₂ to the support point A of the rack 5 and the product of the mass M _{2 of the} rack 5, at least in the direction as compared with the case where the counterweight 15 is not provided. Since the difference between the opposing inertial forces is reduced, the vibration of the sewing machine is reduced.

In the above-described embodiment, the counterweight 15 is fixed to one point of the lever 5, but an oval hole extending in the longitudinal direction is formed in the lever 5, and the oval hole is formed along the oval hole. The counterweight 15 may be attached so as to be movable so that it can arbitrarily cope with variations in weight and size of the lever 5 and the rack 7. In addition, in the above-described embodiment, one counterweight 15 is used, but a plurality of counterweights may be used. In that case, “M ₃ ·
"L ₃ " corresponding to each counterweight (M ₃ · L
₃ = M ₃₁ · L ₃₁ + M ₃₂ · L ₃₂ + M ₃₃ · L ₃₃ + ……).

In the above-described embodiment, the counterweight 15 is fixed to the lever 5 or the rack 7 designed without considering the inertial force, but the lever designed with the inertial force taken into consideration. 5
Alternatively, the counterweight 15 may be fixed to the rack 7 for fine adjustment of the inertial force so that the product variation of the lever 5 or the rack 7 can be corrected.

In the above-described embodiment, the sewing machine in consideration of the inertial force has been described, but CAD for designing parts
The above-mentioned program for products may be used for a device such as to reduce the inertial force that causes vibration.

[0033]

As is apparent from the above description, in the sewing machine according to the first aspect of the present invention, the difference in inertial force between the directions, which is generated by the reciprocating motion of the components for driving the shuttle, is As compared with the case where no counterweight is used, the inertial force acting on the counterweight reduces the vibration, and the vibration generated by the reciprocating motion of the components that drive the hook can be reduced.

Further, in the sewing machine according to the second aspect of the present invention, the sum of the opposing inertial forces in the directions generated by the reciprocating motion of the components for driving the shuttle becomes zero, and the reciprocating motion of the components for driving the shuttle. It is possible to almost prevent the vibration caused by.

Further, in the sewing machine according to the third aspect of the invention, the component for driving the shuttle is designed in consideration of mechanical matters, and the counterweight is attached to the component after the component is manufactured. The degree of freedom in designing parts is maintained as in the past. Further, it is possible to reduce the vibration caused by the reciprocating movement of the components that drive the shuttle.

[Brief description of drawings]

FIG. 1 is an assembly diagram of an inner hook drive mechanism according to an embodiment of the present invention.

FIG. 2 is a diagram showing a force acting on the inner hook driving mechanism.

FIG. 3 is a diagram showing a force acting on the inner hook drive mechanism of another embodiment of the present invention.

FIG. 4 is a diagram of a center hook drive mechanism of a conventional sewing machine.

[Explanation of symbols]

 3 Groove cam 5 Lever 7 Rack 13 Pinion 15 Balance weight

Claims (3)

[Claims] 1. A pinion pivotally supported for rocking the hook, a rack reciprocatingly meshing with the pinion, and a rack pivotably connected to the rack and rocked around a support point. A sewing machine having a lever, the product of the distance from the center of gravity of the lever to the support point of the lever and the mass of the lever, the distance from the center of gravity of the rack to the support point of the lever, and Of the product of the mass of the rack, the counterweight has a counterweight provided on the smaller product side of the support points, and the distance from the center of gravity of the counterweight to the support point of the lever. And the mass of the counterweight, the product of the distance from the center of gravity of the lever to the support point of the lever and the mass of the lever, and the distance from the center of gravity of the rack to the support point of the lever. Less than twice the difference between the product of the rack and the mass of the rack Sewing machine, wherein the door. 2. The product of the distance from the center of gravity of the counterweight to the support point of the lever and the mass of the counterweight is the distance from the center of gravity of the lever to the support point of the lever. 2. The sewing machine according to claim 1, wherein a product of the mass of the lever, a distance from a center of gravity of the rack to a support point of the lever, and a product of the mass of the rack is equal to the difference. 3. The sewing machine according to claim 1, wherein the counterweight is retrofitted to the smaller stacking side with the supporting point as a boundary.