Thread cutter of sewing machine

Abstract

To achieve a thread cutter of a sewing machine which can easily achieve sharpness and holding power of a bobbin thread.SOLUTION: A thread cutter 100 of a sewing machine is capable of adjusting sharpness of thread cutting by adjusting a pressing force for pressing a pressing part 41a of a first plate piece 41 to a movable blade 30 by a pressing power adjustment part 67 adjusting deflection of the first plate piece 41, and capable of adjusting the holding power of a bobbin thread by adjusting a contact pressure for pressing a felt material 50 mounted on a holding part 42a of a second plate piece 42 to the movable blade 30 by a contact pressure adjustment part 68 adjusting deflection of the second plate piece 42. Thereby, each can be adjusted independently, and sharpness of thread cutting and holding power of the bobbin thread can be both achieved relatively easily.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a thread cutting device for a sewing machine.

Background Art

[0002] Conventionally, as a thread cutting device for a sewing machine, a movable blade arranged to overlap a fixed blade is slid, the movable blade is protruded in front of the upper thread and the lower thread, the upper thread and the lower thread are hooked on the hook portion of the movable blade and pulled back, the upper thread and the lower thread are manually drawn closer to the fixed blade side, and the movable blade and the fixed blade are brought into sliding contact to cut the upper thread and the lower thread (see, for example, Patent Document 1).

[0003] For example, a thread cutting device 100 for a sewing machine shown in FIG. 5 includes a fixed blade 2 fixed to a base 1, a movable blade 3 having a hook portion 3a, and a clamp plate 4 that presses the movable blade 3 toward the fixed blade 2. The clamp plate 4 has a pressing piece 4a that abuts on the movable blade 3 and presses the movable blade 3 toward the fixed blade 2, and a holding piece 4b to which a felt material 5 for holding an end portion of the cut lower thread is attached between the movable blade 3. The clamp plate 4 of this thread cutting device 100 for a sewing machine is fixed to the base 1 by an adjustment screw 7 with a spring washer 6 interposed therebetween and a fixing screw 9, and the tightening degree of the adjustment screw 7 is adjusted to adjust the force for pressing the clamp plate 4 against the movable blade 3. For example, by tightening the adjustment screw 7 to strongly press the clamp plate 4 against the movable blade 3, the movable blade 3 pressed by the pressing piece 4a strongly presses against the fixed blade 2, and the felt material 5 of the holding piece 4b strongly presses against the movable blade 3. Then, the force adjustment of the movable blade 3 by the clamp plate 4 is performed by the adjustment screw 7 to ensure the sharpness of the movable blade 3 for cutting the thread, or to ensure the holding force for holding the end portion of the lower thread between the movable blade 3 and the felt material 5.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the case of the thread cutting device 100 of the above-mentioned conventional sewing machine, there has been a problem that it is difficult to achieve both the cutting sharpness by the movable blade 3 and the fixed blade 2 and the holding force of the lower thread by the movable blade 3 and the felt material 5. For example, when adjusting either the cutting sharpness or the holding force by the adjusting screw 7 according to the thickness of the lower thread used for sewing, etc., the other will be affected, so it may take time to adjust to a state where both are achieved. Also, it is cumbersome to replace the felt material 5 only to adjust the holding force, and even when the felt material 5 is replaced in such a way, it may be necessary to adjust the cutting sharpness by the adjusting screw 7.

[0006] An object of the present invention is to provide a thread cutting device for a sewing machine that can easily achieve both cutting sharpness and holding force of the lower thread.

Means for Solving the Problems

[0007] To solve the above problems, the invention according to claim 1 is A thread cutting device for a sewing machine, comprising a fixed blade fixed to a base, a movable blade slidably arranged in sliding contact with the fixed blade, and a clamp plate for pressing the movable blade against the fixed blade, wherein at least the lower thread is cut by the cooperation of the fixed blade and the movable blade, the clamp plate is provided with a pressing portion that abuts against the movable blade and presses the movable blade toward the fixed blade, and a holding portion to which a felt material for holding an end portion of the lower thread cut between the movable blade and the fixed blade is attached, a pressing force adjusting portion for adjusting the force with which the pressing portion presses the movable blade toward the fixed blade, a pressure contact force adjusting portion for adjusting the force with which the holding portion presses the felt material against the movable blade. characterized in that it is provided.

[0008] The invention according to claim 2 is a thread cutting device for a sewing machine according to claim 1, the clamp plate has a first plate piece provided with the pressing portion, a second plate piece provided with the holding portion, and a base end plate piece, and the first plate piece and the second plate piece are plate spring-like members presenting a forked state from the base end plate piece, the pressing force adjusting portion is provided on the base end plate piece in the vicinity of the location where the first plate piece and the second plate piece branch off, the pressure contact force adjusting portion is characterized in that it is provided on the second plate piece.

[0009] The invention according to claim 3 is a thread cutting device for a sewing machine according to claim 2, the second plate piece is arranged so as to straddle the movable blade, and the pressure contact force adjusting portion is provided on the tip side of the second plate piece, characterized in that the movable blade is arranged to slide between the pressure contact force adjusting portion and the pressing force adjusting portion.

[0010] The invention according to claim 4 is a thread cutting device for a sewing machine according to claim 3, the pressing portion is provided on the tip side of the first plate piece, the holding portion is characterized in that it is provided between the pressure contact force adjusting portion and the pressing force adjusting portion on the second plate piece.

[0011] The invention according to claim 5 is a thread cutting device for a sewing machine according to claim 1, the clamp plate is composed of a first clamp plate in the form of a leaf spring provided with the pressing portion and a second clamp plate in the form of a leaf spring provided with the holding portion, the pressing force adjusting portion is provided on the first clamp plate, the pressure contact force adjusting portion is characterized in that it is provided on the second clamp plate.

[0012] The invention according to claim 6 is a thread cutting device for a sewing machine according to claim 5, wherein the pressing portion is provided at the tip of the first clamping plate, and the holding portion is provided at the tip of the second clamping plate.

[0013] The invention according to claim 7 is a thread cutting device for a sewing machine according to claim 5 or 6, wherein the first clamping plate and the second clamping plate are provided in an alternating arrangement straddling the movable blade, and the movable blade is arranged to slide between the pressing force adjusting portion and the pressure contact force adjusting portion.

Advantages of the Invention

[0014] According to the present invention, a thread cutting device for a sewing machine that can easily achieve both sharpness and the holding force of the lower thread can be obtained.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described in detail. The thread cutting device for a sewing machine is installed below the needle plate of the sewing machine and has a function of cutting the upper thread and the lower thread after sewing is completed, and a function of holding the end of the cut lower thread in preparation for the next sewing.

[0017] (Embodiment 1) The thread cutter 100 of the sewing machine according to this embodiment, for example, as shown in FIGS. 1 and 2, includes a base 10 formed by assembling a female base 12 to a sliding plate 11, a fixed blade 20 fixed to the base 10, a movable blade 30 slidably arranged in sliding contact with the fixed blade 20, a clamp plate 40 for pressing the movable blade 30 toward the fixed blade 20, and the like. The fixed blade 20 is disposed between the sliding plate 11 and the female base 12. The movable blade 30 is disposed between the fixed blade 20 and the female base 12, is slid by a drive mechanism (not shown), and moves forward and backward in sliding contact with the fixed blade 20. In this thread cutter 100 of the sewing machine, after sewing is completed, the movable blade 30 is slid by a drive mechanism (not shown), the upper thread and the lower thread hooked on the hook portion 30a of the movable blade 30 are drawn toward the fixed blade 20 side, and the upper thread and the lower thread are cut by the cooperation of the fixed blade 20 and the movable blade 30, and the end portion of the cut lower thread is held. Note that the operation of the thread cutter 100 of the sewing machine is the same as that of the conventionally known one, and thus will not be described in detail here.

[0018] The clamp plate 40 is fixed to the base 10 (female base 12) with a fixing screw 90. The clamp plate 40 is provided with a pressing portion 41a that abuts on the movable blade 30 and presses the movable blade 30 toward the fixed blade 20, and a holding portion 42a to which a felt material 50 for holding the end portion of the lower thread cut between the movable blade 30 is attached. In addition, a pressing force adjusting portion 67 for adjusting the force with which the pressing portion 41a of the clamp plate 40 presses the movable blade 30 toward the fixed blade 20, and a pressure contact force adjusting portion 68 for adjusting the force with which the holding portion 42a of the clamp plate 40 presses the felt material 50 toward the movable blade 30 are provided.

[0019] Specifically, as shown in FIGS. 1 and 2, the clamp plate 40 in the thread cutter 100 of the sewing machine according to Embodiment 1 has a first plate piece 41 provided with a pressing portion 41a, a second plate piece 42 provided with a holding portion 42a, and a base end plate piece 43. The first plate piece 41 and the second plate piece 42 are in a bifurcated manner from the base end plate piece 43 and are plate spring-like members having a substantially Y-shaped configuration. The first plate piece 41 and the second plate piece 42 of the clamp plate 40 are each plate spring pieces having flexibility and being elastically deformable.

[0020] This clamp plate 40 is fixed to the base 10 (female base 12) with fixing screws 90 on the end side of the base end plate piece 43.

[0021] Further, a pressing force adjusting portion 67 is provided on the base end plate piece 43 near the location where the first plate piece 41 and the second plate piece 42 branch. This pressing force adjusting portion 67 is composed of a spring washer 60 and a pressing force adjusting screw 70 screwed to the base 10 (female base 12) with the spring washer 60 interposed therebetween. By adjusting the tightening degree of this pressing force adjusting screw 70 to adjust the deflection of the first plate piece 41, the pressing force for pressing the pressing portion 41a of the first plate piece 41 against the movable blade 30 is adjusted. The pressing portion 41a here has a configuration in which the tip side of the first plate piece 41 is bent in a substantially hook shape, and the pressing portion 41a is provided on the tip side of the first plate piece 41.

[0022] Also, the second plate piece 42 is arranged to straddle the movable blade 30, and a pressure contact force adjusting portion 68 is provided on the tip side of the second plate piece 42. This pressure contact force adjusting portion 68 is composed of a spring washer 60 and a pressure contact force adjusting screw 80 screwed to the base 10 (female base 12) with the spring washer 60 interposed therebetween. By adjusting the tightening degree of this pressure contact force adjusting screw 80 to adjust the deflection of the second plate piece 42, the pressure contact force for pressing the felt material 50 attached to the holding portion 42a of the second plate piece 42 against the movable blade 30 is adjusted. The movable blade 30 is arranged so as to slide between the pressure contact force adjusting part 68 and the pressing force adjusting part 67. Further, the holding part 42a is provided between the pressure contact force adjusting part 68 and the pressing force adjusting part 67 in the second plate piece 42.

[0023] In the thread cutting device 100 of the sewing machine according to the first embodiment having such a configuration, a procedure for adjusting the cutting sharpness of the thread by the movable blade 30 and the fixed blade 20 and the holding force of the lower thread by the movable blade 30 and the felt material 50 will be described.

[0024] First, in order to adjust the cutting sharpness of the thread by the movable blade 30 and the fixed blade 20, the tightening degree of the pressing force adjusting screw 70 of the pressing force adjusting part 67 is adjusted to adjust the pressing force with which the pressing part 41a of the first plate piece 41 presses against the movable blade 30, and the force with which the pressing part 41a presses the movable blade 30 toward the fixed blade 20 is adjusted. Then, the movable blade 30 pressed by the pressing part 41a is adjusted to a state where it appropriately slides in contact with the fixed blade 20, and the cutting sharpness of the thread is ensured.

[0025] Next, in order to adjust the holding force of the lower thread by the movable blade 30 and the felt material 50, the tightening degree of the pressure contact force adjusting screw 80 of the pressure contact force adjusting part 68 is adjusted to adjust the pressure contact force with which the felt material 50 attached to the holding part 42a of the second plate piece 42 presses against the movable blade 30. Then, the felt material 50 is adjusted to a state where it appropriately presses against the movable blade 30 by the holding part 42a, adjusted so that the end part of the lower thread can be appropriately held between the felt material 50 and the movable blade 30, and the holding force of the lower thread after the thread is cut by the movable blade 30 and the fixed blade 20 is ensured.

[0026] Incidentally, when adjusting the tightening degree of the pressing force adjustment screw 70 of the pressing force adjustment unit 67 to adjust the deflection of the first plate piece 41, the second plate piece 42 of the clamp plate 40 is also affected. However, by adjusting the tightening degree of the pressure contact force adjustment screw 80 of the pressure contact force adjustment unit 68 after the adjustment by the pressing force adjustment unit 67, the deflection of the second plate piece 42 can be adjusted by the pressure contact force adjustment unit 68 without affecting the first plate piece 41 of the clamp plate 40. That is, in the thread cutting device 100 of this sewing machine, the deflection of the first plate piece 41 is adjusted by the pressing force adjustment unit 67 to adjust the pressing force for pressing the pressing portion 41a of the first plate piece 41 against the movable blade 30, thereby adjusting the cutting performance of the thread cutting. And the deflection of the second plate piece 42 is adjusted by the pressure contact force adjustment unit 68 to adjust the pressure contact force for pressing the felt material 50 attached to the holding portion 42a of the second plate piece 42 against the movable blade 30, thereby adjusting the holding force of the lower thread. Each can be adjusted independently.

[0027] Thus, in the thread cutting device 100 of the sewing machine according to the first embodiment, the deflection of the first plate piece 41 can be adjusted by the pressing force adjustment unit 67 to adjust the cutting performance of the thread cutting, and the deflection of the second plate piece 42 can be adjusted by the pressure contact force adjustment unit 68 to adjust the holding force of the lower thread. By independently adjusting the cutting performance of the thread cutting and the holding force of the lower thread respectively, both the cutting performance of the thread cutting and the holding force of the lower thread can be made appropriate, so that the cutting performance of the thread cutting and the holding force of the lower thread can be made compatible relatively easily.

[0028] (Embodiment 2) Next, Embodiment 2 of the thread cutting device of the sewing machine according to the present invention will be described. The same parts as those in the first embodiment are denoted by the same reference numerals, and only the different parts will be described.

[0029] The clamp plate 40 in the thread cutting device 100 of the sewing machine according to the second embodiment is composed of a leaf spring-shaped first clamp plate 410 provided with a pressing portion 41a and a leaf spring-shaped second clamp plate 420 provided with a holding portion 42a, as shown in FIGS. 3 and 4. The first clamping plate 410 and the second clamping plate 420 are each a flexible and elastically deformable member.

[0030] A pressing portion 41a is provided at the tip of the first clamping plate 410, and the pressing portion 41a is formed in a manner of bending the tip side of the first clamping plate 410 into a substantially hook shape. In addition, a holding portion 42a is provided at the tip of the second clamping plate 420, and a felt material 50 is attached to the holding portion 42a. The second clamping plate 420 presses the movable blade 30 against the fixed blade 20 via the felt material 50 attached to the holding portion 42a.

[0031] The first clamping plate 410 and the second clamping plate 420 are provided in an alternating arrangement straddling the movable blade 30. Specifically, the pressing portion 41a of the first clamping plate 410 and the holding portion 42a of the second clamping plate 420 face each other, and the first clamping plate 410 and the second clamping plate 420 are provided in a direction where the pressing portion 41a and the holding portion 42a are arranged side by side on the movable blade 30. The first clamping plate 410 is fixed to the base 10 (female base 12) with a fixing screw 90 at the end on the opposite side of the pressing portion 41a, and the second clamping plate 420 is fixed to the base 10 (female base 12) with a fixing screw 90 at the end on the opposite side of the holding portion 42a.

[0032] In addition, a pressing force adjusting portion 67 is provided on the first clamping plate 410. The pressing force adjusting portion 67 is provided between the fixing screw 90 and the pressing portion 41a. The pressing force adjusting portion 67 is composed of a spring washer 60 and a pressing force adjusting screw 70 screwed to the base 10 (female base 12) with the spring washer 60 interposed therebetween. In addition, a pressure contact force adjusting portion 68 is provided on the second clamping plate 420. The pressure contact force adjusting portion 68 is provided between the fixing screw 90 and the holding portion 42a. The pressure contact force adjusting part 68 is composed of a spring washer 60 and a pressure contact force adjusting screw 80 which is screwed to the base 10 (female base 12) with the spring washer 60 interposed therebetween. And the movable blade 30 is arranged so as to slide between the pressing force adjusting part 67 and the pressure contact force adjusting part 68.

[0033] In the thread cutting device 100 of the sewing machine of Embodiment 2 having such a configuration, a procedure for adjusting the cutting edge of the thread cutting by the movable blade 30 and the fixed blade 20 and the holding force of the lower thread by the movable blade 30 and the felt material 50 will be described.

[0034] First, in order to adjust the cutting edge of the thread cutting by the movable blade 30 and the fixed blade 20, the tightening degree of the pressing force adjusting screw 70 of the pressing force adjusting part 67 is adjusted to adjust the deflection of the first clamp plate 410, and the pressing force for pressing the pressing part 41a of the first clamp plate 410 against the movable blade 30 is adjusted, and the force with which the pressing part 41a presses the movable blade 30 toward the fixed blade 20 is adjusted. Then, the movable blade 30 pressed by the pressing part 41a is adjusted to be in a state of appropriately sliding in contact with the fixed blade 20, and the cutting edge of the thread cutting is ensured.

[0035] Next, in order to adjust the holding force of the lower thread by the movable blade 30 and the felt material 50, the tightening degree of the pressure contact force adjusting screw 80 of the pressure contact force adjusting part 68 is adjusted to adjust the deflection of the second clamp plate 420, and the pressure contact force for pressing the felt material 50 attached to the holding part 42a of the second clamp plate 420 against the movable blade 30 is adjusted. Then, the felt material 50 is adjusted to be in a state of appropriately pressing against the movable blade 30 by the holding part 42a, and the end part of the lower thread is adjusted to be appropriately held between the felt material 50 and the movable blade 30, and the holding force of the lower thread after the thread cutting by the movable blade 30 and the fixed blade 20 is ensured.

[0036] Since the first clamp plate 410 and the second clamp plate 420 that constitute the clamp plate 40 of the thread cutter 100 of this second embodiment are independent members, the pressing force adjusting unit 67 adjusts the deflection of the first clamp plate 410 to adjust the pressing force with which the pressing portion 41a of the first clamp plate 410 presses against the movable blade 30, thereby adjusting the sharpness of the thread cutting. Also, the pressure contact force adjusting unit 68 adjusts the deflection of the second clamp plate 420 to adjust the pressure contact force with which the felt material 50 attached to the holding portion 42a of the second clamp plate 420 presses against the movable blade 30, thereby adjusting the holding force of the lower thread. Each can be adjusted independently.

[0037] Thus, in the case of the thread cutter 100 of the sewing machine according to the second embodiment, the pressing force adjusting unit 67 can adjust the deflection of the first clamp plate 410 to adjust the sharpness of the thread cutting, and the pressure contact force adjusting unit 68 can adjust the deflection of the second clamp plate 420 to adjust the holding force of the lower thread. By independently adjusting the sharpness of the thread cutting and the holding force of the lower thread, both the sharpness of the thread cutting and the holding force of the lower thread can be made appropriate, so that it is possible to relatively easily balance the sharpness of the thread cutting and the holding force of the lower thread.

[0038] As described above, in the case of the thread cutter 100 of the sewing machine of this embodiment, it is easy to balance the sharpness and the holding force of the lower thread.

[0039] Note that the application of the present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the spirit of the present invention.

Explanation of Reference Numerals

[0040] 10 Base 11 Slide Plate 12 Female Base 20 Fixed Blade 30 Movable Blade 30a Hook Portion 40 Clamp Plate 41 First Plate Piece 41a Pressing Portion 42 Second plate piece 42a Holding part 43 Base end plate piece 410 First clamp plate 420 Second clamp plate 50 Felt material 67 Pressing force adjustment part 68 Press contact force adjustment part 60 Spring washer 70 Pressing force adjustment screw 80 Press contact force adjustment screw 90 Fixing screw 100 Thread cutting device of sewing machine

Claims

1. A thread cutter for a sewing machine, comprising a fixed blade fixed to a base, a movable blade slidably arranged in sliding contact with the fixed blade, and a clamp plate for pressing the movable blade against the fixed blade, wherein at least the lower thread is cut by the cooperation of the fixed blade and the movable blade, the clamp plate is provided with a pressing portion that contacts the movable blade and presses the movable blade toward the fixed blade, and a holding portion to which a felt material for holding the end of the lower thread cut between the movable blade is attached, a pressing force adjusting portion for adjusting the force with which the pressing portion presses the movable blade toward the fixed blade, and a pressing contact force adjusting portion for adjusting the force with which the holding portion presses the felt material against the movable blade, characterized in that the thread cutter for a sewing machine is provided.

2. The clamp plate has a first plate piece provided with the pressing portion, a second plate piece provided with the holding portion, and a base end plate piece, and the first plate piece and the second plate piece are plate spring-like members presenting a forked configuration branched from the base end plate piece, the pressing force adjusting portion is provided on the base end plate piece in the vicinity of the location where the first plate piece and the second plate piece branch, The thread cutter for a sewing machine according to claim 1, wherein the pressing contact force adjusting portion is provided on the second plate piece.

3. The second plate piece is arranged to straddle the movable blade, and the pressing contact force adjusting portion is provided on the tip side of the second plate piece, The thread cutter for a sewing machine according to claim 2, characterized in that the movable blade is arranged to slide between the pressing contact force adjusting portion and the pressing force adjusting portion.

4. The pressing portion is provided on the tip side of the first plate piece, The thread cutter for a sewing machine according to claim 3, characterized in that the holding portion is provided between the pressing contact force adjusting portion and the pressing force adjusting portion on the second plate piece.

5. The clamp plate is composed of a plate spring-like first clamp plate provided with the pressing portion and a plate spring-like second clamp plate provided with the holding portion, the pressing force adjusting portion is provided on the first clamp plate, The thread cutter for a sewing machine according to claim 1, characterized in that the pressing contact force adjusting portion is provided on the second clamp plate.

6. The sewing thread cutter of the sewing machine according to claim 5, wherein the pressing portion is provided at the tip of the first clamp plate, and the holding portion is provided at the tip of the second clamp plate.

7. The first clamp plate and the second clamp plate are provided in an alternating arrangement across the movable blade. The sewing thread cutter of the sewing machine according to claim 5 or 6, wherein the movable blade is arranged to slide between the pressing force adjusting portion and the pressure contact force adjusting portion.

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