JPH04156882A - Fabric feed device for sewing machine - Google Patents

Abstract

PURPOSE:To prevent a work fabric from being broken or a sewing thread from being cut by detecting the rise of a presser foot. CONSTITUTION:A control means, which controls the drive source of a vertical movement system 72 to lower a feed dog from the upper face of a throat plate based on the detection signal of a detecting means detecting the rise of a presser foot when the presser foot 29 is lifted apart from the throat plate, is provided. A presser bar lifter switch 43 connected to the control device detects the ascent and descent state of the presser foot 29, and the control device controls the vertical movement motor 72 of the feed dog and vertically moves the feed dog in response to the detected state of the switch 43. When a presser bar lifter is operated and the presser foot is lifted apart from the work fabric while a sewing machine is stopped, the feed dog is automatically lowered from the upper face of the throat plate, and the work fabric can smoothly be moved on the throat plate.

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to a cloth feeding device of a sewing machine, and more specifically, when the presser foot of the sewing machine is raised and separated from the work cloth by operating the presser foot lifter, This invention relates to a cloth feeding device that automatically lowers a feeding head from the upper surface of the throat plate in synchronization with the movement of the cloth to allow smooth movement of the work cloth on the throat plate.

Prior Art Sewing machines that perform straight stitches, zigzag stitches, and various other pattern stitches, during sewing operation, swing the needle bar equipped with a sewing needle at a required angle as necessary, and also move the needle plate vertically and backwards and forwards. By applying the necessary feeding motion to the work cloth on the bed with the freely facing feed peg, straight lines and various other patterns are sewn onto the work cloth.

In this case, the sewing needle and the feed dog are set so that they move relative to each other in the required relationship (as can be seen from the graph of the movement trajectory shown in FIG. 8). In other words, the sewing needle is set above the throat plate. , the feed dog protrudes from the top surface of the throat plate and rises to the top dead center position h1, where it captures the work cloth and moves forward. The sewing needle is set to move downward toward the throat plate when the feed of the work cloth stops.Furthermore, before the feeding, the needle moves downward from the upper surface of the throat plate and reaches the bottom dead center position hb. Perform a backward movement.

Problem to be Solved by the Invention During sewing work using the sewing machine, in order to change or correct the sewing position of the workpiece cloth, the sewing is temporarily stopped and the workpiece cloth that is being sewn is moved forward on the bed surface.・Work that involves moving the product backwards or rotating it is generally performed. When the sewing machine stops sewing by operating a start/stop switch or the like, the sewing needle is set to rise to a spaced position above the throat plate (between C and D in FIG. 8) and then stop.

However, in this case, the feed dog that feeds the work cloth stops at a position protruding from the upper surface of the throat plate, as shown in FIG. Therefore, if an attempt is made to move the work cloth in this state as described above, there is a problem in that the work cloth gets caught in the feed dog facing above the throat plate, making it impossible to move the work cloth smoothly. Moreover, if the workpiece cloth caught in the feed dog is forcibly moved in that state, there is a risk that the workpiece cloth will be torn or the sewing thread will be cut.

Purpose of the Invention The present invention has been proposed in view of the above-mentioned problems and to suitably solve the problems. When the presser foot is raised and separated from the workpiece cloth by operating the lifter, the feed pin that feeds the workpiece cloth is lowered from the upper surface of the throat plate, achieving smooth movement of the workpiece cloth on the throat plate. The purpose is to provide the means to do so.

Means for Solving the Problems In order to overcome the above problems and achieve the intended purpose, the present invention provides a presser foot that is movably disposed above the throat plate on which the work cloth is placed, and a A sewing machine comprising a feed dog positioned facing a slit drilled in the feed dog, a vertical movement mechanism that gives vertical movement to the feed dog, and a back and forth movement mechanism that gives back and forth movement to the feed dog, the vertical movement of the feed dog a dedicated drive source for independently driving the mechanism; a detection means for detecting the rise of the presser foot when the presser foot is moved upwardly and away from the throat plate; The present invention is characterized by comprising a control means for controlling the drive source of the vertical movement mechanism so that the feed force is lowered from the upper surface of the throat plate.

According to the present invention, when the sewing machine is stopped, if the presser foot is raised and separated from the work cloth by operating the presser foot, the feed dog is automatically lowered from the upper surface of the throat plate.

Embodiment Next, a preferred embodiment of the cloth feeding device for a sewing machine according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic configuration diagram showing a sewing machine 10 according to an embodiment with a cover 11 removed from a head 24 of the sewing machine 10. As shown in FIG. The main body of the sewing machine 10 includes a pattern display section 14 that displays patterns stored in a ROM 12, which will be described later, and a pattern selection operation section 16 that includes known operation switches for selecting these patterns.
and a display section 18 made of liquid crystal that displays the selected pattern etc. for confirmation. Further, a start/stop switch 26 for controlling starting/stopping of a sewing machine motor 82 (see FIG. 6) is provided on the sewing machine head 24.

(About the basic structure of the sewing machine) A needle bar base 1 is attached to the fixing protrusion 13 provided on the upper part of the head 24.
5 is pivotally supported via a shaft 17 and can swing within a required angle in a vertical plane. The lower part of the needle bar stand 15 is connected to a connecting rod 21 by a shaft 19, and this connecting rod 21 is driven and connected to a needle bar swing control motor 89 shown in FIG. 15 is given a swing within the required angle.

A needle bar 30 is attached to the needle bar stand 15 so as to be able to slide up and down, and a sewing needle 28 is fixed to the lower end of the needle bar 30. This needle bar 30 is connected to a sewing machine motor 82 shown in FIG. 6 via a needle bar holder provided thereon and a main shaft (none of which are shown). By driving the sewing machine motor 82, the needle bar 30 and the sewing needle 28 are given vertical reciprocating motion.

A needle plate 34 is provided in the bed portion 32 of the sewing machine 10, and a feed dog 36 faces upwardly into a plurality of rows of slits 34a formed in the needle plate 34 (see FIG. 5). This feed dog 36 is connected to a longitudinal movement motor 64 and a vertical movement motor 72 shown in FIG. 6 through a feed mechanism 38, which will be described later. As a reference) feed motion is given.

Further, as shown in FIG. 1, a presser bar 27 is fitted into a protrusion 25 provided at a fixed position above the feed dog 36 so as to be movable up and down.
A presser foot 29 is attached to the lower end of this presser bar 27 via a holder 31.

Furthermore, the presser bar 27 is always pressed downward by a presser spring (not shown), and the presser bar holder 3 fixed thereto
3, the presser foot lifter 37 moves the presser foot up and down. That is, a presser foot lifting shaft 39 that intersects with the presser foot bar 27 is rotatably supported on a protrusion 23 provided inside the sewing machine head 24, and a position of the presser foot lifting shaft 39 facing below the presser foot bar holder 33 is supported. A presser foot lifter 37 is fixed to. This presser foot lifter 37 has a required cam shape, and is configured such that the presser bar holder 33 can come into contact with its outer periphery.

Therefore, by rotating the presser foot lifter 37 in the forward and reverse directions, the presser bar holder 33 that contacts the outer periphery of the presser foot lifter 37 moves up and down, as shown in FIGS. 5(a) and 5(b).

The presser foot lifting shaft 39 has a protrusion 23 as shown in FIG.
An eccentric cam 41 is disposed to be integrally rotatable on the opposite side of the presser foot lifter 37. A presser foot lifting switch 43 is disposed near the eccentric cam 41.
The detection piece 43a of No. 3 faces the outer periphery of the eccentric cam 41 so as to be able to come into contact with it.

The eccentric cam 41 is shaped so that when the presser foot lifter 37 is rotated in the forward and reverse directions, it can come into contact with and separate from the detection piece 43a of the presser foot lifter switch 43, thereby turning the switch 43 on and off. It is set. This makes it possible to detect the rise and fall of the presser foot 29.

The relationship between the presser foot lifting switch 43 and the eccentric cam 41 in this embodiment is as shown in FIG. While the presser foot is being pressed, the detection piece 43a comes into contact with the outer periphery of the eccentric cam 41, turning off the presser foot lifting switch 43. Further, when the presser foot 29 is lifted and separated from the workpiece cloth 35 by rotating the presser foot lifter 37 in a predetermined direction to raise the presser foot 27, as shown in FIG. The detection piece 43a is set to move away and turn on the presser foot lifting switch 43.

(About the feeding mechanism of the feed dog) The feed dog 3 facing the slit 34a formed in the throat plate 34
6 is a feed mechanism 38 that operates approximately in synchronization with the needle bar 30;
It is connected to the. As shown in FIG.
It basically consists of a back-and-forth movement mechanism 42 that provides horizontal back-and-forth movement to the feed dog 6, and a vertical movement mechanism 44 that provides up and down movement to the feed dog 36.

(Regarding the forward and backward movement mechanism) A board 50 is provided horizontally inside the bed portion 32,
The feed table 40 is disposed on the substrate 50 so as to be movable back and forth and up and down by a mechanism to be described later. That is, as shown in FIGS. 2 and 4, the feed table 40 is formed in an inverted U-shape, and the feed dog 36 is fixed to the upper surface of the upper horizontal portion 40a with a screw 46. Also, feed stand 4
The lower horizontal part 40b of 0 is formed with an overhanging part 40c that extends horizontally on the front side (the side facing the operator), and a long hole 48 in the front-rear direction is bored in this overhanging part 40c. . A guide bin 52 vertically protruding from the base plate 50 slidably faces the elongated hole 48, and when the back-and-forth movement mechanism 42 operates, the feed bar 40 acts as a guide for the bin 52 facing the elongated hole 48. It is configured to move back and forth in a straight line.

As shown in FIG. 3, a pivot pin 56 is erected on the base plate 50 at a position close to the feed table 40, and a horizontal arm 54 is pivoted to the pin 56 so as to be rotatable in the horizontal direction. This horizontal arm 54 consists of a first arm part 54a and a second arm part 54b, each extending in opposite directions about the pivot point. The first arm portion 54a is connected to the feed base 40
The distal end thereof faces between the upper horizontal portion 40a and the lower horizontal portion 40b of the feed table 40. Further, a shaft 58 that protrudes in the vertical direction is vertically fixed to the tip of the first arm portion 54a, and the upper and lower ends of this shaft 58 are connected to the corresponding upper and lower horizontal portions 40a, 4
It is slidably inserted into a through hole bored in 0b. Note that the upper end of the shaft 58 is also commonly inserted through a through hole bored in the feed dog 36 fixed to the feed base 40.

Further, the lower horizontal portion 40b of the feed table 40 and the first arm portion 5
As shown in FIG. 4, a compression spring 60 wound around the shaft 58 is elastically interposed between the shaft 58 and the shaft 58. Therefore, the feed bar 40 is always urged downward under the elastic action of the compression spring 60, and the lower surface of the overhang 40c is brought into contact with a contact member 67 provided on a vertical arm 68, which will be described later. ing.

The second arm portion 54b extends in a direction away from the feed base 40, and has a sector gear 62 integrally formed at its tip, as shown in FIG. This sector gear 62 is a motor 6 for longitudinal movement arranged vertically on the board 50.
It meshes with the pinion 66 of No. 4. Therefore, by driving the forward and backward movement motor 64, the horizontal arm 54 rotates about the pivot pin 56, and moves the feed base 40 and the feed dog 36, which are supported by the first arm portion 54g via the shaft 58, forward. and horizontally driven backwards. As mentioned above, the elongated hole 4 of the overhanging portion 40c of the feed base 40
Since a guide pin 52 protruding from the base plate 50 is inserted through the guide pin 8, the feed bar 40 is guided by the guide pin 52 and moves linearly back and forth.

(Regarding the Vertical Movement Mechanism) As shown in FIGS. 2 and 4, a support piece 71 is provided at an appropriate position on the board 50, that is, at a position close to the overhanging part 40c of the feed table 40. A vertical arm 68 is rotatably supported in the vertical direction by a pivot pin 69 pushed laterally. The vertical arm 68 has a first arm portion 68a and a second arm portion 68b extending in opposite directions from each other about the pivot portion thereof. The first arm portion 68a extends toward the feed table 40 from the pivot portion as a base point, and has its tip facing below the projecting portion 40c of the feed table 40.

The projecting portion 40c is biased downward under the elastic action of the compression spring 60 and comes into contact with a cylindrical contact member 67 provided at the tip of the first arm portion 68a.

Further, the second arm portion 68b of the vertical arm 68 is connected to the feed base 4.
0 and intersects with the horizontal arm 54 below. And the second arm part 68b
A sector gear 70 integrally formed at the tip of the sewing machine is meshed with a pinion 74 of a vertical motor 72 disposed laterally on the sewing machine body. Therefore, this vertical movement motor 7
2, the vertical arm 68 rotates in the vertical direction about the pivot pin 69 as a fulcrum, as shown in FIGS. 5(a) and 5(b). The feed table 40 that comes into contact with the roller is driven up and down. At this time, the feed base 40 and the feed dog 36 are connected to the horizontal arm 5.
It is guided by a vertical shaft 58 provided on the first arm portion 54a of No. 4, and moves up and down while maintaining a parallel posture.

That is, when the feed dog 40 is biased by the vertical movement mechanism 44 and given vertical movement, the feed dog 40 moves to its top dead center position hl.
and at the bottom dead center position hb, the back and forth movement mechanism 42 drives the bed portion 3 forward and backward, respectively.
2 is moved in a predetermined direction.

By controlling the vertical movement motor 72 by a control device 80 shown in FIG. 6, only the feed dog 36 can be moved vertically when the sewing machine 10 is stopped.

Further, a hook 78 is rotatably supported on the base plate 50 at a position close to the feed dog 36 (FIG. 3), and the hook 78 is driven by a stamping motor 76 shown in FIG. 2 disposed on the base plate 50. It is designed to be rotationally driven.

(About the electrical control system) FIG. 6 is a block diagram showing an outline of the electrical control system that controls each operating member of the sewing machine according to the embodiment, and shows a control device 80 based on a microprocessor (CPU).
It is equipped with A pattern selection operation section 16, a start/stop switch 26, a timing signal generator 93, and a presser foot lifting switch 43, which will be described later, are connected to the control device 80, respectively.

Note that the timing signal generator 93 is connected to the sewing machine motor 82.
, needle bar swing control motor 89, longitudinal movement motor 64, vertical movement motor 72, and hook driving stepping motor 76.
It generates signals related to each operation timing.

Furthermore, the control device 80 includes a sewing machine motor 82 via a drive circuit 81 and a needle bar swing control motor 8 via a drive circuit 90.
9. A motor 64 for longitudinal movement of the feed weight 36 is connected via a drive circuit 83, a motor 72 for vertical movement of the feed awl 36 is connected via a drive circuit 84, and a stimping motor 76 for driving the hook is connected via a drive circuit 94. There is. Note that the control device 80
The presser foot lifting switch 43 connected to detects the raising and lowering states of the presser foot 29, and the control device 80 controls the vertical movement motor 72 of the front feed 36 according to the detected state of the switch 43. is controlled to move the feed pin 36 up and down.

Further, the ROM 12 as a memory element stores pattern data 91 that can be selected by the pattern selection operation unit 16, and the read/write RAM 92 temporarily stores the results of calculations by the control device 80, etc. By operating the pattern selection operation section 16, a code signal corresponding to the selected pattern is supplied to the control device 80.

(Regarding the flow of the control system) Next, FIG. 7 shows an operation flow when each signal is supplied to the control device 80 in the sewing machine according to the embodiment. After the sewing preparations such as threading are completed, the sewing machine 10 is
After starting (power ON) in step 101 (hereinafter [step J is referred to as 184)], it is confirmed whether the presser foot lift switch is OFF (the presser foot 29 is lowered). If the result is affirmative (YES), the process moves to 5103, where a desired pattern is selected from the various patterns stored in the ROM 12 using the pattern selection operation section 16. Then 51
04, it is confirmed whether the start/stop switch 26 is turned on, and if it is affirmative (YES), the process proceeds to 5105;
Each drive motor 82, 89, 64, 72 is driven to perform the required sewing.

Then, at 5106, the start/stop switch 26 is turned on again.
If it is negative (No), return 5107.
It is confirmed whether the pattern data 91 in the ROM 12 has been completed. If the sewing has not been completed (NO), the process returns to step 5105 to continue driving the drive motors 82, 89, 64, and 72 to perform sewing. Also, the end of pattern data 91 is affirmed (
(YES), in 5108 each drive motor 82,
Stop driving 89, 64°72. Note that when each of the drive motors 82, 89, 64, and 72 is stopped at 5108, the sewing needle 28 is located above the throat plate 34 as described above, and the feed dog 36 protrudes from the upper surface of the throat plate 34. .

Next, in step 5109, it is confirmed whether the presser foot lifting switch 43 has been turned on, and if the answer is affirmative (YES), it means that the presser foot 29 has been raised, so the process moves to 5110. Then, the vertical movement motor 72 is driven, and the feed fi 36 is lowered by a required amount via the vertical movement mechanism 44 shown in FIG. (See Figure 5(b)). At this time, the work cloth placed on the throat plate 34 does not contact and interfere with the feed dog 36, so that the work cloth 35 can be smoothly moved on the upper surface of the throat plate 34. Next, at 5111, the presser foot lifter switch 43 is set to 0.
Check if FF (presser foot 29 is lowered) is done, and confirm (Y).
If ES), the process proceeds to 5112, where the vertical movement motor 72 is driven to cause the feed 1iI36 to protrude from the upper surface of the throat plate 34 again. Note that the amount of movement of the feed dog 36 in this case is controlled by the control device 80 so as to be the same as the amount of movement lowered in step 5110.

Operation of the Embodiment Next, the actual use of the cloth feeding device of the sewing machine according to the present embodiment will be explained.

When the sewing preparation work is completed, and before starting the operation of the sewing machine 10, the pattern selection operation section 16 is operated to input a desired pattern to be sewn.

The pattern selected by this input is displayed on the display section 1, for example.
8 is displayed. At this time, the presser foot 29 is lowered and presses the work cloth 35 placed on the bed portion 32 between it and the throat plate 34, as shown in FIG. It is in the OFF state.

Next, when the start/stop switch 26 is operated to input a start signal to the control device 80, the sewing machine motor 82 is driven via the drive circuit 81 according to the control program stored in the ROM 12, and the needle bar 30 is moved. It is moved up and down. Further, according to the pattern data 91 stored in the ROM 12, the needle bar swing control motor 89 is driven by the drive circuit 90, and the needle bar 30 is swung in a direction perpendicular to the cloth feeding direction. Further, according to the pattern data 91 stored in the ROM 12, the forward and backward movement motor 64 and the vertical movement motor 72 of the feed dog 36 are driven via drive circuits 83 and 84, respectively.

Due to the vertical movement and rocking movement of the needle bar 30 and the vertical movement and back-and-forth movement of the feed #136, which are controlled in advance in this way, the pattern data 9 is transferred to the work cloth 35 placed on the bed portion 32.
Various patterns according to 1 are sequentially sewn.

Here, when the sewing machine 10 is stopped in order to change the sewing position of the work cloth 35 or to change the sewing direction, the sewing needle 28 stops at the upper position raised and separated from the throat plate 34, and the feed #I3 stops in a state protruding from the upper surface of the needle plate 34 (see FIG. 5(a)). Next, when the presser foot lifter 37 is operated to raise and separate the presser foot 29 from the workpiece cloth 35, the presser foot lifter switch 43 is turned on by the eccentric cam 41, as shown in FIG. 5(b).

This signal is input to the control device 80, as shown in FIG. 6, and drives the vertical movement motor 72 to lower the feed dog 36 from the upper surface of the throat plate 34 via the vertical movement mechanism 44. In this state, the work cloth 35 can be smoothly moved without being caught by the feeder 36.

In order to sew the work cloth 35, the presser foot lifter 37 is operated again to lower the presser foot 29, and the work cloth 35 is pinched between the presser foot 29 and the throat plate 34. At this time, the presser foot lifter switch 43 is turned off in conjunction with the operation of the presser foot lifter 37. Therefore, this signal is input to the control device 80, and the vertical movement motor 72 is driven to raise the feed dog 36 by the same amount as the amount by which it was lowered. As a result, the feed signal 36 returns to the state when the sewing machine 10 was stopped, and the workpiece cloth 35 is normally transferred by turning on the start/stop switch 26.

That is, by raising and lowering the presser foot lifter 37, the feed rate 111 is increased.
36 can be moved up and down, and when the sewing machine is stopped, the work cloth 35 can be smoothly moved on the upper surface of the throat plate 34.

In addition, since the amount of protrusion of the feed dog 36 from the upper surface of the throat plate when the sewing machine is stopped is approximately constant as shown in FIG. 8, the amount of elevation of the feed #36 when operating the presser foot lifter 37 should be set constant. I can do it.

In this embodiment, a case has been described in which the vertical movement mechanism and the longitudinal movement mechanism of the feed dog are driven by independent dedicated motors, but the present invention can also be implemented by driving the feed dog longitudinal movement mechanism by a sewing machine motor. Applicable. Further, the hook does not need to be driven by a dedicated motor; it may be driven by a sewing machine motor as in the past.

As described in detail, according to the cloth feeding device of the sewing machine according to the present invention, it is possible to detect the rise of the presser foot and lower the feed dog from the upper surface of the throat plate. In this way, when the sewing machine is stopped and the presser foot is raised to move or rotate the workpiece cloth, the feed blind is always automatically positioned below the top surface of the throat plate. The work cloth is not caught by the feed dog and can be moved smoothly. Moreover, since no special operations are required, there is no burden on the operator.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a schematic configuration of a sewing machine in which the present invention is preferably carried out, FIG. 2 is a schematic perspective view showing a feed mechanism for a feed neck in a sewing machine according to an embodiment, and FIG. Fig. 2 is a plan view of the feeding mechanism shown in Fig. 2, Fig. 4 is a front view of the feeding mechanism shown in Fig. 2, and Figs. Explanatory front view shown in Figure 6
FIG. 7 is a block diagram of the control system of the sewing machine according to the embodiment.
The figure is a flowchart diagram of a sewing machine according to an embodiment,
FIG. 8 is a graph showing the locus of movement of the sewing needle and the feed neck. 29... Presser foot 34... Nameplate 34a...
・Slit 35...Working cloth 36...Feed t
42... Back-and-forth movement mechanism 43... Presser foot lifter switch 44... Vertical movement * 72... Vertical movement motor 80... Control device

Claims (1)

[Scope of Claims] A presser foot (29) disposed movably up and down above the throat plate (34) on which the work cloth (35) is placed, and the throat plate (34)
a feed dog (36) located facing the slit (34a) drilled in the feed dog (36); a vertical movement mechanism (44) that gives the feed dog (36) vertical movement; and a vertical movement mechanism (44) that gives the feed dog (36) back and forth movement. In a sewing machine equipped with a back-and-forth movement mechanism (42),
a dedicated drive source (72) that independently drives the vertical movement mechanism (44) of the feed dog (36); Detection means (
43), and a control means (80) for controlling the drive source (72) of the vertical movement mechanism (44) to lower the feed dog (36) from the upper surface of the throat plate based on the detection signal of the detection means (43). )
A cloth feeding device for a sewing machine characterized by comprising: