JP5142568B2 - Sewing machine presser foot - Google Patents

Description

  The present invention relates to a cloth presser device for a sewing machine.

2. Description of the Related Art Conventionally, in a sewing machine including a presser device that holds a sewing product by applying a pressing force from above to the sewing material on the needle plate, a stepping motor or the like is used as a drive source for raising and lowering the presser foot. A method using an electric actuator is known (for example, Patent Document 1).
FIG. 6 is a perspective view showing a part of the configuration of a presser foot mechanism of a presser device for a sewing machine according to the prior art. The sewing machine presser mechanism 110 includes a support frame 122 whose base end is held by the cloth moving mechanism and whose distal end is positioned at an arbitrary position along the XY plane, and under the presser foot 121. The lower plate 123 that is located on the side and holds the workpiece between the presser foot 121, the presser holding member 124 that is erected on one end portion of the presser foot 121, and the tip end portion of the support frame 122. A guide frame 125 that supports the presser foot 121 through the holding member 124 so as to be able to move up and down, and is supported by the support frame 122 so as to be swingable. A pair of swinging rods 126 to be applied, a pressing plate 127 supported by a sewing machine frame so as to be movable up and down, and supported at an upper portion of the support frame 122 so as to be swingable, and one end portion is below the pressing plate 127 The first and second link bodies 129 and 130 that interlock the other end of the swing member 128 and the other end of each swing bar 126 in the same direction vertically. A tension spring 131 that connects the other end of the flange 26 and one end of the first link body.

Further, the sewing machine presser device includes a power transmission mechanism 150 that applies a downward pressing force to the pressing plate 127. When the driving force of the stepping motor is transmitted by the power transmission mechanism 150 and the support shaft 27a of the pressing plate 127 is pressed downward, one end of the swing member 128 is lowered and the other end is raised, and each link member The other end of the swinging rod 126 is also pulled upward via the 129 and 130 and the tension spring 131. As a result, one end of the swing bar 126 is pushed downward, and the presser foot 121 is pressed downward via the holding member 124 that moves downward along the guide frame 125, so that the presser foot 121 and the lower plate 123 are pressed. The sewing product is held in between.
JP 2006-304992 PR

By the way, in the cloth presser device for a sewing machine according to the above-described prior art, the downward pressing force applied from the power transmission mechanism 150 is always constant regardless of the cloth thickness of the workpiece. On the other hand, since the cloth thickness of the sewing product varies depending on the sewing object, it is necessary to adjust the pressing force applied from above to the sewing object from the cloth presser 121 according to the cloth thickness of the sewing object. For this reason, in the prior art, the tension spring 131 that connects one end portion of the link member 129 and the other end portion of the swinging rod 126 expands in accordance with the upward movement position of the presser foot 121 due to the cloth thickness. Thus, the pressing force adjustment to the sewing object by the cloth presser 121 has been performed. At this time, the degree of extension of the tension spring 131 is determined by the cloth thickness of the sewing product. If the sewing object is thin, the extension of the tension spring 131 is small, and if the sewing object is thick, the extension of the tension spring 131 is growing. That is, the pressing force generated by the tension spring is weak when the workpiece is thin, and the pressing force generated by the spring is strong when the workpiece is thick. Therefore, the pressing force of the presser foot 121 against the sewing product changes depending on the thickness of the sewing product. As a result, there is a problem that the pressing force by the presser foot 121 is too weak when the sewing product is thin and the sewing product cannot be held sufficiently, and the pressing force by the presser foot 121 is too strong when the sewing product is thick. There is a problem that distortion occurs in the sewing product.
In order to solve the above-described problems in the prior art, it is necessary to individually use the tension spring 131 having an optimal spring constant for each cloth thickness of the sewing object. For this reason, the tension spring 131 is replaced every time the workpiece is changed, which is very complicated and requires a lot of time for the replacement work. It was.

  In view of the above-described problems, an object of the present invention is to provide a presser foot device that applies an optimum pressing force to a sewing product.

The invention described in claim 1 includes a presser foot mechanism that supports the presser foot that is lowered onto the needle plate and holds the workpiece to be raised and lowered, and a driving means that is a drive source for raising or lowering the presser foot, And a power transmission mechanism for transmitting a driving force of the driving means as a driving force for raising or lowering the presser foot, wherein the presser foot has a target value of pressure applied to the sewing product. A first storage means for storing; a control means for driving the drive means; a detection means for detecting an actual operation amount of the drive means; and a second reference value for storing a pressure reference value for lowering the presser foot comprising storage means, and wherein if the pressing force based on the deviation between the actual amount of operation of said driving means detected by the scheduled operation quantity and said detection means of said driving means is equal to or less than the reference value, Lowering the presser foot at the first speed If the pressing force exceeds the reference value, the cloth presser is controlled to decrease the lowering speed at the second speed, and when the pressing force matches the target value, Control is performed to stop the lowering of the presser foot .
The “target value of the pressure that the presser foot applies to the workpiece” may be the pressure value itself, but is another value that has a known relationship with the pressure value, such as a deviation value that causes the pressure. May be good.
Further, the above-mentioned “reference value of pressure for lowering the presser foot” may be the pressure value itself, but is another numerical value having a known relationship with the pressure value, such as a deviation value causing the pressure. May be good.

Invention of Claim 2 is the cloth presser device of the sewing machine of Claim 1 , Comprising: When the said control means exceeds the target value of the pressure memorize | stored in said 1st memory | storage means, Is characterized by lowering the presser foot again after reversing the driving direction of the presser foot by the driving means.

According to the first aspect of the present invention, the control means detects the deviation between the scheduled operation amount of the drive means and the actual operation amount of the drive means detected by the detection means, and the target value of the pressure stored in the first storage means. Based on the pressure reference value stored in the second storage means, the pressure applied to the workpiece by the presser foot is adjusted to the target value. Therefore, regardless of the thickness of the material to be sewn, the pressure applied to the material to be sewn by the presser foot is adjusted by the control means so as to be a target value. This eliminates the need for complicated and time-consuming work such as replacement of the tension spring in the prior art. Therefore, the work required for the presser foot to apply the optimum pressing force to the sewing product is greatly simplified and comfortable, and the time required for holding the sewing product by the presser foot device is greatly reduced. Thus, the burden on the operator can be greatly reduced.
Moreover, the efficiency of the sewing work by the sewing machine is greatly increased by the above-described effect, and the cycle time of the sewing work can be greatly shortened. Therefore, a highly productive sewing machine can be provided.
Furthermore, since there is no need to provide a mechanism for deformation like a tension spring, and there is no need to install or remove the tension spring for replacement, a highly durable durable cloth presser device is provided. In addition, it is possible to eliminate the possibility of parts deterioration or parts loss due to frequent parts replacement. Therefore, it is possible to provide a sewing machine presser device that has few failures and is generally stable and reliable.

According to the second aspect of the present invention, when the pressure based on the deviation between the scheduled operation amount of the drive means and the actual operation amount of the drive means detected by the detection means exceeds the target pressure value, the control means is the drive means. After raising the presser foot by reversing the driving direction, the presser foot is lowered again. That is, when the pressure that the presser foot applies to the workpiece is too strong, the presser foot is once raised to reduce the pressure, and then lowered again to readjust the pressure to the target value. As a result, the pressure applied by the presser foot to the sewing product is adjusted more optimally, so that it is possible to provide a presser foot device that applies a more optimal pressing force to the sewing product.

(Overall configuration of the embodiment of the invention)
Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. FIG. 1 is a perspective view illustrating a part of a main configuration of a sewing machine cloth presser according to an embodiment of the present invention. FIG. 2 is a perspective view illustrating a part of a main configuration of a sewing machine cloth presser. It is the perspective view seen from a different direction.
A sewing machine including a cloth presser device for a sewing machine according to the present invention includes a sewing machine frame (not shown) that holds or stores each component, and the sewing machine frame includes a bed portion positioned at a lower portion of the entire sewing machine, and a sewing machine bed. A longitudinal body portion erected upward at one end portion in the longitudinal direction of the portion, and an arm portion extending in the same direction as the bed portion from the upper end portion of the longitudinal body portion. In the following description, with the sewing machine placed on a horizontal plane, the direction that is horizontal and parallel to the longitudinal direction of the bed portion is the Y-axis direction, the direction that is horizontal and orthogonal to the Y-axis direction is the X-axis direction, The direction orthogonal to the Y-axis direction is taken as the Z-axis direction.

The presser device 10 of the sewing machine serves as a driving source for lifting and lowering the presser foot 21 and a presser foot mechanism 20 that supports the presser foot 21 that is lowered onto the needle plate and holds the sewn product to be sewn. A stepping motor 13 as “driving means”, a power transmission mechanism 50 that applies the rotational driving force of the stepping motor 13 to the presser foot mechanism 20, and a control device 70 as “control means” for controlling the stepping motor are provided. Yes.
The sewing machine also has a vertical movement mechanism for holding the sewing needle to move up and down, a hook mechanism for binding the lower thread to the upper thread inserted through the sewing needle below the needle plate, and the presser foot mechanism 20. Various mechanisms required for sewing are provided, such as a cloth moving mechanism for moving the cloth presser 21 along the upper surface of the needle plate 11 to arbitrarily perform the needle drop position. And the description is omitted.

(Cloth presser mechanism)
The presser foot mechanism 20 has a base end portion thereof held by the cloth moving mechanism and a distal end portion thereof positioned at an arbitrary position along the XY plane, and a lower side of the presser foot 21. A lower plate 23 that is positioned and holds the workpiece between the presser foot 21, a presser holding member 24 that is erected at one end of the presser foot 21, and a holding member that is provided at the front end of the support frame 22 A guide frame 25 that supports the presser foot 21 so as to be able to move up and down via 24, and is supported by the support frame 22 so as to be swingable. A pair of oscillating rods 26, a pressing plate 27 supported by a sewing machine frame so as to be movable up and down, and an oscillating member that is supported at the upper part of the supporting frame 22 and that has one end in contact with the lower surface of the pressing plate 27. In addition to the member 28 and the swing member 28 First causes the parts and the other end portion of the oscillation beam 26 is interlocked about the vertical in the same direction, and a second and third link member 29, 30, 31.

FIG. 3 is a side view showing the configuration of the presser foot mechanism. 3A shows a state where the presser foot 21 is raised, and FIG. 3B shows a state where the presser foot 21 is lowered.
The presser foot 21 is a rectangular frame, and the insides of the four sides are greatly opened. Needle drop is performed on the sewing object held inside the opening, and sewing is performed.
Correspondingly, the lower plate 23 also has a rectangular frame portion that is approximately the same size as the presser foot 21, and is opened wide like the presser foot 21. Furthermore, the lower plate 23 has an extending portion that extends in parallel with the short side from a portion corresponding to the middle of the long side, and is held by the cloth moving mechanism at the tip of the extending portion. And the rectangular frame part side with the front-end | tip part of the support frame 22 is positioned in the arbitrary positions along XY plane.

  The support frame 22 is disposed on the upper surface of the sewing machine bed portion, and as described above, the base end portion thereof is held by the cloth moving mechanism, and the front end portion thereof gradually moves forward from above with respect to the base end portion. It is extended to. The longitudinal direction (extending direction) of the support frame 22 is provided on the sewing machine bed portion so as to be along the Y-axis direction.

The presser holding member 24 is formed in a substantially L shape, and one end thereof is fixedly connected to the cloth presser 21, and the other end is supported by the guide frame 25.
The guide frame 25 is fixedly installed at the distal end portion of the support frame 22 and includes a guide groove that slidably supports the other end portion of the holding member 24. The guide frame 25 is mounted on the support frame 22 so that the guide groove extends along the Z-axis direction (vertical direction). As a result, the presser foot 21 can move up and down with respect to the support frame 22.

  Each swing rod 26 is provided so as to sandwich the support frame 22, and is supported by the support frame 22 in a state substantially along the Y-axis direction. Further, each swing rod 26 is supported by the support frame 22 so as to be swingable about an axis along the X-axis direction at an intermediate portion in the longitudinal direction, and one end portion for swinging is supported by the guide frame 25. Is inserted into a through hole provided in the other end portion of the holding member 24 supported by the. Accordingly, when the one end of the swing bar 26 moves up and down due to the swinging movement of the swing bar 26, the presser foot 21 also moves up and down via the presser holding member 24. In addition, each swing bar 26 is always biased in the direction in which the presser foot 21 moves upward by a torsion coil spring (not shown) at the shaft support portion.

The pressing plate 27 is a rectangular flat plate, and includes a support shaft 27a that is fixedly erected vertically at the center of the upper surface thereof. The support shaft 27a has a round bar shape and is inserted into a cylindrical metal bearing 32 fixedly mounted on the sewing machine frame, and the pressing plate 27 is supported by the support shaft 27a so as to be movable up and down along the Z-axis direction. ing.
Further, the upper end portion of the support shaft 27a protrudes upward from the metal bearing 32, and pins 27b are provided on both ends in the radial direction of the upper end portion of the support shaft 27a. Each pin 27a is engaged with the power transmission mechanism 50 to receive a downward pressing force input.

The swing member 28 is disposed on the support frame 22 in a state along the Y-axis direction. The swinging member 28 is supported by the support frame 22 so as to be swingable about the axis along the X-axis direction at the middle portion in the longitudinal direction, and one end portion that moves up and down by the swinging is the lower surface of the pressing plate 27. It is the arrangement | positioning contact | abutted to the center part.
On the other hand, the other end of the swing member 28 is connected to the other end of each swing bar 26 (the end opposite to the cloth presser 21) via three link bodies 29, 30, 31. Since the other end of each swing rod 26 is biased downward by a torsion coil spring, the other end of the swing member 28 is also biased downward via the three link bodies 29, 30, 31. As a result, the one end portion of the swing member 28 is biased upward with the elasticity of the torsion coil spring, and as a result, the pressing plate 27 always maintains a state of being pushed upward.
The first link body 29 described above is swingably supported by the support frame 22, and the second link body 30 includes the swing end portion of the first link body 29 and the other end of the swing member 28. Connected to the department. The first link body 29 is connected to the other end portion of the swing rod 26 by the third link body 31. Therefore, when the swing end portion of the first link body 29 swings upward, the other end portion of the swing rod 26 is also pulled upward.

Normally, the presser foot mechanism 20 is biased in a direction in which the swing bar 26 pulls up the presser foot 21 upward by a torsion coil spring. In other words, as long as no external force is applied, the presser foot 21 and the lower plate 23 are kept separated as shown in FIG.
When the support shaft 27a of the pressing plate 27 is pressed downward by the power transmission mechanism 50, one end portion of the swing member 28 is lowered and the other end portion is raised, and the link members 29, 30, 31 are moved. Accordingly, the other end of the swing rod 26 is also lifted upward. As a result, as shown in FIG. 3B, the presser foot 21 is pressed downward, and the sewing product is held between the presser foot 21 and the lower plate 23.

(Power transmission mechanism)
As shown in FIGS. 1 and 2, the power transmission mechanism 50 includes a rotating cam 52 that is simultaneously driven to rotate by the stepping motor 13, and a roller member 56 that moves around the output shaft 13 a of the stepping motor 13 according to the rotating cam 52. And a lever member 57 that supports the roller member 56 at one end and swings according to the circular movement of the roller member 56, and a driven link body 59 that is fixed to the lever member 57 and swings together with the lever member 57. A pair of arm members 60 and 61 that press down the pin 27b of the cloth presser mechanism 20 by a swinging operation, and a long power transmission plate 62 that connects the swinging end of the driven link body 59 and the arm member 60. And.

The two arm members 60 and 61 are both fixedly connected simultaneously to a support shaft 66 rotatably supported by the sewing machine frame above the cloth presser mechanism 20, and the two arm members 60 and 61 are connected to the two arm members 60 and 61. The pivot 66 is integrated with the support shaft 66 to swing.
The swing end of each arm member 60, 61 extends in the radial direction of the circle centered on the support shaft 66 and along the Y-axis direction, and the pressing plate 27 of the cloth presser mechanism 20 described above is provided. It is located above each pin 27b to be moved up and down. That is, when the swinging end portions of the arm members 60 and 61 are moved down by swinging, the arm members 60 and 61 come into contact with the pins 27b, and the presser foot 27 is moved down so that the presser foot 21 presses the sewing product. Yes.

  One arm member 60 has an input piece 60a, to which the swing driving force is input, extending in the Z-axis direction in the radial direction centering on the support shaft 66, separately from the swing end contacting the pin 27b. It is installed. One end of a power transmission plate 62 is connected to the input piece 60a, and the input piece 60a is swung along the Y-axis direction. Thereby, each arm member 60 and 61 whole rocks.

  The power transmission plate 62 is long and is disposed along the Y-axis direction in the sewing machine arm portion. As described above, since the other end of the power transmission plate 62 is connected to the swinging end of the driven link body 59, the power transmission plate 62 advances along the longitudinal direction by the swing of the driven link body 59. The arm members 60 and 61 are oscillated by moving (moving direction f) and moving backward (moving direction b). That is, during the backward movement, the arm members 60 and 61 swing in the direction in which the pin 27 b of the presser foot mechanism 20 is pressed, and press the presser foot 21. At the time of forward movement, the arm members 60 and 61 swing in a direction away from the pin 27b of the presser foot mechanism 20 to move the presser foot 21 upward from the pressed state.

The roller member 56 is disposed in contact with the outer periphery of the rotating cam 52 and moves around the output shaft 13 a of the stepping motor 13 according to the rotation of the rotating cam 52. The roller member 56 is applied with a tension so as to always come into contact with the outer periphery of the rotating cam 52 by a tension spring 67 provided on the driven link body 59.
The lever member 57 is formed in a substantially L shape, and is pivotally supported on the sewing machine frame by a support shaft 65 at a bent portion thereof. The lever member 57 is pivotally supported by an axis along the X-axis direction, and when the roller member 56 located at one end moves substantially along the Z-axis direction by the revolving motion, the other end is approximately the Y-axis. It is bent to move along the direction.

The driven link body 59 is supported by the sewing machine frame so as to be rotatable by the support shaft 65 together with the lever member 57 at one end portion in the longitudinal direction. Further, the other end in the longitudinal direction of the driven link body 59 is connected to the other end of the power transmission plate 62. The driven link body 59 swings integrally with the lever member 57, and each arm member according to the forward movement (movement direction f) or the backward movement (movement direction b) of the power transmission plate 62 along the Y-axis direction. 60 and 61 are swung, and the lifting / lowering state of the presser foot 21 is switched.

The rotating cam 52 has a roller member 56 in contact with the outer peripheral surface thereof and moves according to the outer peripheral shape, whereby the rotary cam 52 is moved in accordance with the distance from the output shaft 13a of the stepping motor 13 at each position on the outer peripheral surface. A function of swinging the member 57 is provided.
The rotary cam 52 is mounted on the output shaft 13a of the stepping motor 13, and the outer peripheral shape of the rotary cam 52 is set so that the presser foot 21 moves up and down as the output shaft 13a rotates. That is, the rotating cam 52 is a so-called eccentric cam.

  Due to the shape of the rotary cam 52, when the distance between the output shaft 13a and the roller member 56 is reduced by the rotation of the rotary cam 52, the power transmission plate 62 interlocked with the roller member 56 as described above moves forward along the Y-axis direction. (Moving direction f) is performed. Accordingly, the presser foot 21 is raised. Further, when the distance between the output shaft 13a and the roller member 56 is increased by the rotation of the rotary cam 52, the power transmission plate 62 interlocked with the roller member 56 moves backward (moving direction b) along the Y-axis direction as described above. Do. Accordingly, the presser foot 21 is lowered.

(Stepping motor)
The stepping motor 13 rotates in synchronization with the pulse signal output from the control device 70. Further, the stepping motor 13 includes an encoder as “detection means” that detects the rotation angle of the output shaft 13 a of the stepping motor 13 and outputs the rotation angle to the control device 70.
The phase of the stepping motor 13 in the rotational movement of the output shaft 13a is controlled by a control device 70 described later. Specifically, the output shaft 13 a of the stepping motor 13 is controlled to rotate to a predetermined phase by a pulse signal output by the control device 70. On the other hand, a mechanical load is generated in the rotational movement of the output shaft 13a of the stepping motor 13 by the power transmission mechanism 50 and the cloth presser mechanism 20 connected to the output shaft 13a. Therefore, when the mechanical load is large, the phase of the output shaft 13a of the stepping motor 13 (hereinafter referred to as “input pulse phase”) based on the pulse signal output by the control device 70 and the stepping motor actually performed Deviation occurs between the phases of the 13 output shafts 13a (hereinafter referred to as “actual phases”). The degree of the deviation is determined by the mechanical load by the power transmission mechanism 50 and the presser foot mechanism 20 described above. At this time, since the load due to friction or the like generated in each part of the power transmission mechanism 50 and the cloth presser mechanism 20 is substantially constant, the increase / decrease in the deviation is mainly determined by the pressing force T by which the cloth presser 21 presses the cloth from above. It will be.
That is, the encoder detects the actual phase of the stepping motor 13 and outputs it to the control device 70, so that the control device 70 presses the cloth presser 21 from above based on the input pulse phase and the actual phase. The pressure T can be calculated.

(Control device)
FIG. 4 is a block diagram showing a configuration of the control device 70 and a configuration electrically connected to the control device 70.
The control device 70 stores a set value T2 as a “target value of pressure” for the pressing force with which the presser foot 21 presses the cloth from above, and sets the input pulse phase and the actual phase based on the detection of the encoder. A storage unit 71 as a “first storage unit” and a “second storage unit” that stores a high-speed descent allowable value T1 that is a reference value for lowering the presser foot 21 at a high speed when the deviation is less than a certain value; Based on the pulse signal output unit 72 that outputs a pulse signal for driving the stepping motor 13, the input pulse phase by the pulse signal output unit 72, and the actual phase by the encoder of the input pulse stepping motor 13, A pressing force T for pressing the cloth from above is calculated, and when the pressing force T exceeds the high speed lowering allowable value T1 stored in the storage unit 71, the lowering speed of the cloth presser 21 is calculated. In addition to functioning as a “second adjusting means” for decreasing, it also functions as a “first adjusting means” for stopping or reversing the rotational motion of the stepping motor 13 by comparing the pressing force T with the set value T2 of the pressing force. And an arithmetic unit 73.

The memory | storage part 71 memorize | stores the setting value T2 of the pressing force in which the cloth presser 21 presses a cloth from upper direction. The set value T2 is set by the operator via the input interface. Therefore, the storage unit 71 functions as a “first storage unit”.
Further, the storage unit 71 stores a high-speed descent allowable value T1 that is a reference value for lowering the presser foot 21 at a high speed when the deviation between the above-described input pulse phase and the actual phase is equal to or less than a certain value. When the deviation is equal to or less than the high speed lowering allowable value T1, the high speed lowering allowable value T1 is determined that the presser foot 21 has not yet reached the workpiece and the presser foot 21 is not subjected to a load. It is a reference value for When the calculation unit 73 of the control device 70 determines that the presser foot 21 has not reached the sewing product based on the deviation and the high-speed lowering allowable value T1, the lowering speed of the presser foot 21 is increased. On the other hand, when the deviation exceeds the high-speed descent allowable value T1, it is determined that the presser foot 21 has reached the workpiece and the presser foot 21 is under load, and the lowering speed of the presser foot 21 is reduced. To do. Thereby, the time required for the presser foot 21 to hold the workpiece can be shortened as compared with the case where the presser foot 21 always moves up and down at a constant speed. Therefore, the storage unit 71 functions as a “second storage unit”.
Further, the storage unit 71 stores a pressing force conversion table for obtaining the value of the pressing force T from above on the workpiece to be sewn by the presser foot 21 from the deviation value between the input pulse phase and the actual phase. . The calculation unit 73 calculates the value of the pressing force T from the deviation and the pressing force conversion table, and compares the value of the pressing force T with the set value T2, so that the value of the pressing force T is appropriate. Is determined.

The set value T2 may be set so as to be selectable from a plurality of pressing force set values stored in advance in the storage means, or a numerical value may be directly input by an operator.
Further, the high-speed descent allowable value may be a fixed value, or may be changed like the above-described set value T2.
Further, in addition to the above, the storage unit 71 stores various programs and data executed by the calculation unit 73. Further, since it is desirable that the set value T2, the high-speed descent allowable value T1, the pressing force conversion table, and various programs and data can be held even after the sewing machine is turned off, the storage unit 71 is a non-volatile storage device (for example, an EPROM). ).

The pulse signal output unit 72 outputs a pulse signal for driving the stepping motor 13.
Further, the pulse signal output unit 72 increases or decreases the pulse signal in accordance with an instruction from the calculation unit 73. That is, the calculation unit 73 adjusts the driving of the stepping motor 13 by increasing or decreasing the pulse signal performed by the pulse signal output unit 72. The arithmetic unit 73 maintains a prescribed pulse output when high speed driving is required, and outputs a pulse signal obtained by subtracting 1 from the previous output pulse number when low speed driving is required.

  The calculation unit 73 calculates a pressing force T at which the presser foot 21 presses the cloth from above based on the input pulse phase by the pulse signal output unit 72 and the actual phase by the encoder of the input pulse stepping motor 13, and The rotational speed and direction of the stepping motor 13 are adjusted on the basis of the pressure T, the high-speed descent allowable value T1 stored in the storage unit 71, and the set value T2 of the pressing force.

A mechanism in which the vertical movement of the presser foot 21 is controlled by the calculation unit 73 will be described in detail with reference to the flow of FIG.
When the presser foot is operated by the operator's operation, the calculation unit 73 instructs the pulse signal output unit 72 to descend to the stepping motor 13 at a high speed. As a result, the presser foot 21 descends at a high speed (step S1), and the actual phase is output from the encoder of the stepping motor 13. The calculation unit 73 calculates a deviation between the input pulse phase based on the command to the pulse signal output unit 72 and the actual phase, and based on the value of the deviation and the pressing force conversion table stored in the storage unit 71. The value of the pressing force T applied to the workpiece by the work clamp 21 is calculated (step S2). At this time, the calculation unit 73 compares the calculated pressing force T with the high-speed descent allowable value T1 of the storage unit 71 (step S3). When the value of the pressing force T is equal to or less than the high-speed descent allowable value T1, the calculation unit 73 instructs the pulse signal output unit 72 to continue the descent to the stepping motor 13 at a high speed. When the value of the pressing force T exceeds the high speed drop allowable value T1, the calculation unit 73 instructs the pulse signal output unit 72 to drop to the stepping motor 13 at a low speed. As a result, the lowering of the presser foot 21 becomes low speed (step S4). The processing of step S1 to step S3 is performed until the presser foot descends at a low speed when the value of the pressing force T exceeds the high speed descending allowable value T1.

  Even when the presser foot 21 descends at a low speed, the actual phase is output from the encoder of the stepping motor 13 as in the above-described process. The calculation unit 73 calculates the value of the pressing force T applied to the sewing product by the presser foot 21 by the same process as described above (step S5). At this time, the calculation unit 73 compares the calculated pressing force T with the set value T2 of the storage unit 71 (step S6). If the value of the pressing force T is less than the set value T2, the calculation unit 73 instructs the pulse signal output unit 72 to continue to lower the stepping motor 13 at a low speed. If the pressing force T is not less than the set value T2 in step S6, the calculation unit 73 determines whether the pressing force T is the same as the set value T2 (step S7). The value of the pressing force T is the same as the set value T2. In some cases, the calculation unit 73 instructs the pulse signal output unit 72 to stop outputting the pulse signal to the stepping motor 13 in order to stop the stepping motor 13. As a result, the presser foot 21 stops (step S8), and the position of the presser foot 21 in the up-and-down movement is a position at which the pressing force T according to the set value T2 is applied to the sewing product.

  On the other hand, when the value of the pressing force T is not less than the set value T2 and not the same as T, that is, when the pressing force T exceeds the set value T2, the calculation unit 73 outputs the increased power to the stepping motor 13. The pulse signal output unit 72 is instructed to do so. As a result, the presser foot is raised (step S9), and the presser foot 21 is slightly lifted in order to reduce the pressing force caused by the presser foot 21 that has become too large with respect to the workpiece. After that, the process returns to step S5, the descent is resumed, and the calculation unit 73 commands the pulse signal output unit 72 to output the low-speed descent power to the stepping motor 13 according to the flow. As a result, the presser foot 21 descends again at a low speed. The above-described processing is performed until the presser foot 21 stops because the value of the pressing force T becomes the same as the set value T2.

That is, when the pressing force T is equal to or less than the high-speed lowering allowable value T1, the calculation unit 73 determines that the presser foot 21 is not in contact with the workpiece and lowers the presser foot 21 at high speed. As a result, the time required for the presser foot 21 to hold the workpiece can be shortened.
When the pressing force T exceeds the high speed lowering allowable value T1, the calculation unit 73 determines that the presser foot 21 has started to apply the pressing force to the workpiece, and lowers the presser foot 21 at a low speed. As a result, the pressing force applied to the sewing product by the work clamp 21 is finely adjusted. Therefore, the calculation unit 73 of the control device 70 functions as a “second adjustment unit”.
Further, when the pressing force T becomes the same as the set value T2, the calculation unit 73 determines that the pressing force applied to the workpiece by the presser foot 21 has become the pressing force intended by the operator, and stops the presser foot 21. . As a result, the pressing force from above on the workpiece by the presser foot 21 becomes the optimum pressing force.
Furthermore, when the pressing force T exceeds the set value T2, the calculation unit 73 determines that the pressing force applied to the sewing product by the presser foot 21 is too strong, and raises the presser foot. As a result, the pressing force that has been applied to the presser foot 21 is alleviated, and fine adjustment is possible by lowering again at a low speed. Therefore, the calculation unit 73 of the control device 70 functions as a “first adjustment unit”.

(Function and effect)
According to the above-described embodiment, the calculation unit 73 of the control device 70 calculates the pressing force T from the input pulse phase of the stepping motor 13 and the actual phase of the stepping motor 13 output by the encoder, and the presser foot 21 is sewn. Adjustment is made so that the pressing force applied to the object becomes the set value T2. Therefore, regardless of the thickness of the material to be sewn, the pressing force that the presser foot 21 applies to the material to be sewn is adjusted by the adjusting means so that it becomes the set value T2. This eliminates the need for complicated and time-consuming work such as replacement of the tension spring in the prior art. Therefore, the work for the presser foot 21 to apply the optimum pressing force to the sewing product is greatly simplified and comfortable, and the time required for holding the sewing product by the presser device is greatly reduced. Thus, the burden on the operator can be greatly reduced.
Moreover, the efficiency of the sewing work by the sewing machine is greatly increased by the above-described effect, and the cycle time of the sewing work can be greatly shortened. Therefore, a highly productive sewing machine can be provided.
Furthermore, since there is no need to provide a mechanism for deformation like a tension spring, and there is no need to install or remove the tension spring for replacement, a highly durable durable cloth presser device is provided. In addition, it is possible to eliminate the possibility of parts deterioration or parts loss due to frequent parts replacement. Therefore, it is possible to provide a sewing machine presser device that has few failures and is generally stable and reliable.

  When the pressing force T exceeds the high speed drop allowable value T1, the calculation unit 73 of the control device 70 instructs the pulse signal output unit 72 to supply the low speed drop power to the stepping motor 13. As a result, when the pressing force T exceeds a certain value, that is, when the presser foot 21 reaches the sewing product, the presser foot 21 descends at a low speed, so that the change of the pressing force applied to the sewing product is moderated. To. Therefore, the work of optimally adjusting the pressing force applied by the presser foot 21 to the sewing product can be realized easily and quickly, and the time required for holding the sewing product by the presser foot 21 can be further shortened.

  Further, when the pressing force T exceeds the set value T2, the calculation unit 73 of the control device 70 instructs the pulse signal output unit 72 to supply the low-speed descending power to the stepping motor 13. That is, when the pressing force applied to the workpiece by the presser foot 21 is too strong, the presser foot 21 is once raised to reduce the pressing force, and then lowered again to make the pressing force the same as the set value T2. Readjust. As a result, the pressing force applied to the sewing product by the presser foot 21 is adjusted more optimally, so that it is possible to provide a presser device that applies a more optimal pressing force to the sewing product.

(Other)
In the above-described embodiment, the stepping motor is used as the driving means. However, any driving means that can drive the presser foot and that can adjust the driving amount thereof may be used. For example, a solenoid may be used.
In addition, the configurations of the presser foot mechanism 20 and the power transmission mechanism 50 of the above-described embodiment are merely examples, and the configurations are limited to the above-described embodiments as long as the mechanism can transmit the driving force by the driving means as raising and lowering the presser foot. It goes without saying that it is not done.
In the above-described embodiment, the function of the control device 70 is realized by software processing. However, the control device 70 may be realized by dedicated components or analog circuits that perform the same function for each processing.

  In addition, when the same sewing product and the set value are used by storing the cloth presser stop position based on the set value of the pressing force with respect to the sewing product in the storage means in association with each other. The stop position may be reproduced. At this time, the cloth thickness may be detected based on the position where the cloth presser is stopped.

It is the perspective view which illustrated a part of main structure of the cloth presser device of the sewing machine which is embodiment of this invention. It is the perspective view seen from the direction different from FIG. 1 which illustrated some main structures of the cloth presser apparatus of a sewing machine. 4 is a side view showing the configuration of the presser foot mechanism 20. FIG. 3A shows a state where the presser foot 21 is raised, and FIG. 3B shows a state where the presser foot 21 is lowered. 2 is a block diagram showing a configuration of a control device 70 and a configuration electrically connected to the control device 70. FIG. 5 is a flowchart showing a mechanism for raising and lowering the presser foot 21 by a calculation unit 73 of the control device 70. It is the perspective view which showed a part of structure of the presser foot mechanism of the presser device of the sewing machine by a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Sewing presser device 13 Stepping motor 20 Presser mechanism 21 Presser foot 23 Lower plate 27 Press plate 50 Power transmission mechanism 52 Rotating cam 56 Roller member 57 Insulating member 59 Drive link body 60, 61 Arm member 62 Power transmission plate 70 Control Device 71 Storage unit 73 Calculation unit

Claims (2)

A presser foot mechanism that descends onto the needle plate and supports the presser foot that holds the workpiece to be raised and lowered;
A driving means serving as a driving source for raising or lowering the presser foot;
A power transmission mechanism for transmitting a driving force of the driving means as a driving force for raising or lowering the presser foot, and a presser device for a sewing machine comprising:
First storage means for storing a target value of pressure applied to the sewing product by the presser foot;
Control means for driving the drive means;
Detecting means for detecting an actual operation amount of the driving means;
Second storage means for storing a reference value of pressure for lowering the presser foot ,
Wherein, the speed when pressing force based on the deviation between the actual operation amount is equal to or less than the reference value, the presser foot first the driving means detected by the scheduled operation quantity and said detection means of said driving means When the pressing force exceeds the reference value, the lowering speed of the presser foot is decreased to be lowered at a second speed, and the pressing force is set to the target value. A cloth presser device for a sewing machine, which controls to stop the lowering of the presser foot when they match . When the pressing force exceeds the target pressure value stored in the first storage unit, the control unit reverses the driving direction of the presser foot by the driving unit and then lowers the presser foot again. The sewing machine presser device according to claim 1 ,

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