JPS6151912B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cloth presser foot that is detachably attached to the lower end of a presser bar of a sewing machine.

When sewing a zigzag pattern such as satin stitch, or when sewing multiple threads in parallel at narrow intervals, if the seams cannot be seen through the presser foot, the position of the seams cannot be confirmed and the stitches will be sewn accurately and beautifully. It is difficult to

For this reason, it has been proposed to make the entire presser foot molded from transparent synthetic resin, but synthetic resin has high frictional resistance and wears easily, so the fabric does not slip easily, causing minute patterns to collapse, and sharp feeds. There were drawbacks such as the bottom surface of the presser foot wearing out in a short period of time due to friction between the teeth and the cloth.

Therefore, it has been proposed to attach a thin iron plate to the bottom of a transparent synthetic resin presser foot, but even in this case, the synthetic resin part exposed on the bottom is likely to wear out, and if used for a long time, the thin iron plate will disappear. However, there was an unavoidable drawback that the cloth could not be fed smoothly due to the difference in level in the mirror field.

In addition, in either case, the connecting shaft that attaches the presser foot to the holder at the lower end of the presser bar lacks strength if it is made of the same synthetic resin as the presser foot.
Since it is necessary to manufacture the metal separately from the presser foot and press fit it into the insertion hole of the presser foot, the manufacturing process is not only complex and requires a large number of connecting shafts with different diameters and lengths to be kept in stock. The drawback was that parts management was complicated.

The present invention eliminates these conventional drawbacks,
The presser foot body and its connecting shaft are integrally cast from metal, and the tip of the transparent resin part with a needle hole is inserted into the cavity of the presser foot body that extends below the connecting shaft. By fitting the parts together, it is possible to see through the seams through the transparent resin part during sewing, and it also allows for smooth sliding between the cloth and the metal body, and in addition, it is possible to avoid the conventional connecting shaft insertion hole. The purpose is to simplify manufacturing by omitting the drilling process and connecting shaft press-fitting process.

The present invention will be described based on the embodiments shown in the drawings. A indicates a metal presser foot body, and B indicates a transparent synthetic resin portion having a needle droplet 1 (FIG. 1).

A pair of left and right support pieces 2, 2 protrude from the upper surface of the main body A, and a connecting shaft 3 is integrally suspended between them.
As shown in FIG. 9, the connecting shaft 3 has both ends 3
a, 3a are formed thicker than the central portion 3b to supplement strength. Then, a removable pin 5 is provided on the holder 4 that is fixed to the lower end of the presser bar of the sewing machine, and the holder 4 is inserted between both support pieces 2, 2, and the tip of the removable pin 5 is attached to the center part 3b of the connecting shaft 3. By protruding downward, the presser foot is detachably connected to the holder 4.

As shown in FIGS. 2 and 3, the central portion of the main body A is cut from the front to a position below the connecting shaft 3 to form a cavity 6 for inserting the resin part, and the tip is curved upward. A pair of sled-shaped cloth presser pieces 7, 7 are formed along both left and right sides of the main body A, and the base ends of both cloth presser pieces are integrally connected by a base section 8 of the main body A.

An upwardly inclined surface 9 is formed on the front edge of the main part 8 extending over the presser foot pieces 7, 7, and a guide groove 10 is formed on the bottom surface of the main part 8 along the center thereof.

Further, concave portions 12, 12 are formed on the upper surfaces of the left and right presser pieces 7, 7 through U-shaped stepped portions 11 that open inwardly when viewed from above. Reference numeral 13 denotes curved portions forming both left and right end portions of the needle droplet 1.

Then, the horizontal spacing between the support pieces 2, 2 is narrower than the horizontal spacing between the fabric presser pieces 7, 7, and the gap between the fabric presser pieces 7, 7 and the inner surfaces of the support pieces 2, 2 is formed so as to fit into the stepped portion where the inner surfaces of the fabric presser pieces 7, 7 and the inner surfaces of the support pieces 2, 2 meet. One end of the support pieces 2, 2 is made to protrude, and thereby the downward floating prevention surfaces 14, 14 protruding into the cavity 6 for inserting the resin part are placed adjacent to the rear of the concave portions 12, 12 on the cloth presser pieces 7, 7. One pair is formed along the inner edge of the left and right sides.

Reference numerals 15 and 15 indicate eave-like engaging protrusions that protrude from the inner surfaces of the cloth presser pieces 7, 7 adjacent to the front of the recessed portions 12, 12.

In order to manufacture this metal presser foot body A, the joint surface XX of the upper die and the lower die of the casting mold is cut into a space 6 for inserting the shaft fat part only at the connecting shaft 3, as shown in FIG. pierce upward and bulge, and align with a horizontal plane containing the axis of the connecting shaft 3. Then, by injecting and filling the mold with a heated and molten metal such as zinc alloy, the presser foot main body A in which the connecting shaft 3 is integrally horizontally suspended between the support pieces 2 and 2 is completed as described above.

Subsequently, the surface of this main body A is polished with an abrasive to remove burrs generated on the mold joint surface XX, and the entire body is finished smooth, and then plated.

Next, a transparent synthetic resin part B matching the shape of the resin part insertion cavity 6 of the main body A is manufactured separately by a known manufacturing method, and its thickness is adjusted to the thickness of the guide groove 10 of the main part 8 of the main body A. They are formed equally, and only the left and right wings of the resin part B are made thinner.

The synthetic resin part B is not limited to a completely transparent body but may be semi-transparent as long as it can be seen through, and it is convenient if it is lightly colored in red or blue within the range that can be seen through so that various types of presser feet can be immediately identified.

A thread introduction hole 16 that reaches the needle drop hole 1 is bored in the center of the resin part B, and the width L of the thread introduction hole 16 is longer than the height H of the left and right engagement protrusions 15 provided on the main body A. It should be shorter than the sum of the two (Figure 5).

To assemble the synthetic resin part B to the metal presser foot body A, insert one end of the resin part B from below the connecting shaft 3 between the left and right support pieces 2, 2, and bring it into contact with the front edge of the main part 8. , a part of the upper surface of the resin part B is inserted under the floating prevention surfaces 14, 14 and tightly fitted therein. Then, while compressing the width of the thread introduction hole 16 against the elasticity of the resin part B, the left and right wings of the resin part B are fitted into the recessed part 12, and the left and right sides of the other end of the resin part B are fitted into the engaging protrusion. The resin part B is engaged with the strip 15, thereby fitting the resin part B into the resin part insertion cavity 6 of the main body A.

Here, the width L of the thread introduction hole 16 is the width L of the left and right engaging protrusions 1
5, and even if the width of the thread introduction hole 16 is completely compressed and the inner wall of the thread introduction hole is brought into close contact with the inner wall of the thread introduction hole, it will not be possible to ride over the left and right engaging protrusions 15 at the same time. It is necessary to lock them one by one, but on the other hand, once they are locked, the resin part B
It has the advantage that it does not fall off from the engaging protrusions 15, 15 unnecessarily.

Therefore, the thickness of the resin part B is equal to the thickness at the center of the main body part 8 of the main body A, that is, the thickness at the guide groove 10 of the main part 8, so that the bottom surface of the resin part B is lower than the bottom surface of the presser pieces 7, 7. is also high (Figure 5).

And the recessed parts 12, 12 and the step part 1 on the periphery thereof,
1 and 11 support the resin portion B against external forces acting downwardly and in the front, rear, left, and right directions, and floating prevention surfaces 14 and 14 support the resin portion B against external forces acting upward. Similarly, the upwardly inclined surface 9 of the main body 8 opposes the downward external force, and the engaging protrusions 15, 15 support the resin part B against the upward and downward external forces, respectively.

In short, the presser foot of the present invention consists of a metal presser foot body A and a transparent synthetic resin portion B, and the body A has a pair of left and right support pieces 2, 2 protruding from the upper surface thereof.
A resin part B is provided with a connecting shaft 3 horizontally suspended integrally between
has a needle drop hole 1 and a thread introduction hole 16 communicating with the needle drop hole 1, and the center portion of the main body A is cut out from the front to a position below the connecting shaft 3 to form a cavity 6 for inserting the resin part. At the same time, a pair of sled-shaped cloth presser pieces 7, 7 whose tips are curved upward are formed along both left and right sides of the main body A, and the base ends of both cloth presser pieces are attached to the main body A.
The upper surfaces of the presser pieces 7, 7 are provided with concave portions 12, 12, and the inner edges thereof are provided with downward floating prevention surfaces 14, 14 and engaging protrusions 15, 15. Blank space 6 for inserting resin part each
A guide groove 10 is provided in the center of the bottom surface of the main body 8 to protrude inward, and then the resin part B is formed in the same shape as the cavity 6 for inserting the resin part, and its thickness is adjusted to the center of the bottom surface of the main body 8. The bottom surface of the resin part B is made higher than the bottom surfaces of the presser pieces 7, 7, and the resin part B is inserted under the floating prevention surfaces 14, 14, and the recessed parts 12, 12 and It is characterized in that the resin part B is integrally fixed in the resin part insertion cavity 6 of the main body A by fitting into the engaging protrusions 15, 15.

Therefore, according to the presser foot of the present invention, the area around the needle hole 1 can be clearly seen through the transparent synthetic resin part B, so it is possible to accurately sew a zigzag pattern or the like while checking the seams during sewing. The bottom surface of part B is higher than the presser pieces 7, 7 and does not press the cloth strongly, and the cloth is mainly pressed by the metal presser pieces 7, 7 with a low coefficient of friction, so the cloth slides well and the resin part B It also has the effect of not wearing out.

Further, the concave portion 12, the floating prevention surface 14, and the engaging protrusion 15 formed on the main body A cooperate with each other, and have the effect of reliably fixing the resin portion B in the space 6 in an immovable state.

In the manufacturing method of the present invention, the joint surface XX of the upper mold and lower mold of the casting mold is connected to the resin part insertion cavity 6
A metal presser foot body A is cast, in which the connecting shaft 3 is integrally horizontally suspended between a pair of left and right support pieces 2, 2 that protrude upward and protrude higher than the upper surface of the body A. Therefore, the presser foot main body A having the connecting shaft 3 can be manufactured in one step, and the connecting shaft can be manufactured separately from the presser foot as in the conventional method, or the insertion hole for attaching the connecting shaft can be made in the supporting pieces 2, 2. There is no need to drill holes at all, which has the effect of greatly shortening the manufacturing process and improving productivity.

Furthermore, in the present invention, the synthetic resin part B is formed separately from the metal presser foot main body A, and this is inserted into the resin part insertion cavity 6 of the main body A, so the main body A is placed in the synthetic resin molding die. Compared to the method of molding the resin part B integrally with the main body A by placing the resin part B at a position, by inserting one end of the resin part B deeply to the rear of the connecting shaft 3, the lower part of the connecting shaft 3 can be closed by the resin part B. Therefore, there is no problem in the sliding of the cloth, and there is also an effect that no burrs are generated on the interface between the main body A and the resin portion B.

[Brief explanation of the drawing]

Fig. 1 is an overall perspective view showing the usage state of the presser foot embodying the present invention, Figs. 2 and 3 are drawings of the main body of the metal presser foot, Fig. 2 is a perspective view of its top surface, and Fig. 3 is a perspective view of the presser foot according to the present invention.
The figure is a perspective view of the bottom surface, Figure 4 is a plan view of the presser foot shown in Figure 1, Figure 5 is a cut end view taken along the - line in Figure 4, and Figure 6 is the metal presser foot shown in Figure 4. A plan view of only the main body, FIG. 7 is a sectional view taken along the line - in FIG. 6, FIG. 8 is a sectional view taken along the line - in FIG. 6, and FIG. 9 is an enlarged perspective view of the connecting shaft in the embodiment of the present invention. The figure shows a part of it cut away.

Claims (1)

[Scope of Claims] 1. Consisting of a metal presser foot body A and a transparent synthetic resin portion B, the body A has a connecting shaft that integrally extends horizontally between a pair of left and right support pieces 2, 2 that protrude from the upper surface of the body A. 3, the resin part B has a needle drop hole 1 and a thread introduction hole 16 communicating with the needle drop hole 1, and the main body A is cut out from the front to a position below the connecting shaft 3, and the resin part B has a needle drop hole 1 and a thread introduction hole 16 communicating therewith. A sled-shaped presser piece 7, 7 having an upwardly curved tip and forming a cavity 6 for insertion is attached to the main body A.
A pair of presser plates are formed along both the left and right sides of the presser plate, and the base ends of both presser pieces are integrally connected by the base portion 8 of the main body A.
In addition, there are downward floating prevention surfaces 14, 14 on the inner edge.
Then, the engaging protrusions 15, 15 are respectively projected into the cavity 6 for inserting the resin part, and a guide groove 10 is provided in the center of the bottom surface of the main body 8, and then the resin part B is inserted into the cavity 6 for inserting the resin part. The resin part B is formed into the same shape and has a wall thickness equal to the thickness of the center of the bottom surface of the main body 8, so that the bottom surface of the resin part B is higher than the bottom surface of the presser pieces 7, 7, and this resin part B is floated. blocking surface 14,
14, and also fits into the recesses 12, 12 and the engaging protrusions 15, 15 to integrally fix the resin part B in the resin part insertion cavity 6 of the main body A. Sewing machine presser foot. 2. The joint surface (X-X) of the upper and lower molds of the casting mold penetrates above the cavity 6 for inserting the resin part in the center of the presser foot body A, and is raised higher than the upper surface of the body A. A metal presser foot body A is cast in which a connecting shaft 3 is integrally suspended between a pair of left and right support pieces 2, 2 protruding from the upper surface of the body, and a needle drop hole 1 and a thread introduction hole 16 communicating therewith are cast. After molding a transparent synthetic resin part B having the same shape as the resin part insertion cavity 6 and polishing the surface of the main body A, the thread introduction hole 1 is molded.
This method of manufacturing a presser foot for a sewing machine is characterized in that the width of the synthetic resin part B is compressed against the elasticity of the resin part B, and the synthetic resin part B is inserted into the resin part insertion cavity 6 and fitted onto the main body A.