JPH0424084A - Needle guard device of multi-thread chain stitch arm sewing machine - Google Patents

Abstract

PURPOSE:To surely guide a needle to a normal position by bringing a needle guard member into contact with a needle having been sticked through a fabric to be sewn from the fabric feed side to guide the needle to a normal position, while the needle makes a reciprocating motion below feed teeth of a needle guard drive shaft. CONSTITUTION:Since a needle guard drive shaft 11 makes a reciprocating motion corresponding to the rotation of a machine main shaft 8, said motion is in synchronous relationship with the vertical motion of a needle bar, i.e., a needle 7. Hence when the needle 7 begins to downwardly move, a needle guard member 21 driven by the shaft 11 is moved from the side of feeding fabric in a direction shown by an arrow B opposite to a direction A. When the needle 7 is bent to the feed side of fabric when it is sticked through the fabric, a corresponding vertical side 21a of the member 21 comes to the side of the bent needle 7 from the fabric feed side and abuts against the needle 7, so that the needle 7 is pushed back in a direction B (fabric feed direction). As a result, the needle 7 is guided to a normal position and made straight in a vertical direction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention (Industrial Field of Application) The present invention relates to a needle guide device for a double ring arm sewing machine that performs double ring mending of work cloth in an arm portion of a sewing machine frame.

(Prior art) A double chainstitch arm sewing machine, which is a sewing machine dedicated to sewing cylindrical objects, has a needle that moves up and down based on the rotation of the main shaft of the sewing machine, a looper that captures and rotates the needle thread, and a processing machine in the arm part of the sewing machine frame. Double chainstitching is performed on the workpiece fabric using a feed dog or the like that feeds the fabric.

By the way, when the work cloth is thick, when the needle penetrates the work cloth, the needle tip passes through the part of the work cloth where there is less resistance, so when the needle penetrates the work cloth, the needle tip It also tends to be crooked so that it slips from its normal position. When the needle moves up after penetrating the work fabric, the looper, which captures the needle thread and makes a turning movement, is located on the fabric delivery side of the rising needle, so when the needle passes through the pressurized fabric, the looper If it bends toward the feeding side, it will interfere with the looper or needle.

For this reason, conventionally, a fixed type needle guide member is installed inside the arm of the sewing machine frame and guides the needle that bends in the cloth feeding direction to the correct position, or a fixed type needle guide member is installed in the cloth feeding mechanism including a feed dog to guide the needle that bends in the cloth feeding direction. A moving type needle guide member is provided which is moved in a direction opposite to the feeding direction and guides the needle to a normal position.

(Problems to be Solved by the Invention) With the configuration of the conventional fixed type needle guide member, when the fabric to be processed is extremely thick or the needle is thin, the needle may bend more than expected. There are problems in which the needle collides with the needle guide member and breaks, or the needle thread is incompletely captured by the looper, resulting in skipped thread breakage.

In addition, with the configuration of the conventional moving needle guide member, when the cloth feed pitch by the cloth feed mechanism is changed, the timing of the needle guide by the needle guide member is shifted. There is a problem in that the position of the guide member must be adjusted.

The present invention has been made in view of the above circumstances, and its purpose is to ensure that a needle guide member guides a needle to its proper position, thereby preventing needle breakage, skipped stitches, and thread breakage. To provide a needle guide device for a double ring mending arm sewing machine which is capable of providing the following functions and eliminates the need to adjust the position of a needle guide part +4 even when the double feed repitch is changed.

[Structure of the Invention (Unique Means for Solving the Problems) The present invention uses a needle, a looper, a feed dog, etc., which are moved based on the rotation of the main shaft of the sewing machine in the arm portion of the sewing machine frame, to perform double chainstitching on work cloth. In a double chainstitch arm sewing machine, a needle guide drive shaft is disposed within the arm portion and is moved linearly back and forth in response to the rotation of the sewing machine main shaft. The present invention is characterized by a structure in which a needle guide member is connected to the needle, which reciprocates and descends through the work cloth, and which approaches the needle from the cloth delivery side and guides it to a proper position.

(Function) According to the needle guide device of the double chainstitch arm sewing machine of the present invention, the needle guide member moves from the cloth feed center [, at the lower position of the feed dog] and guides the needle to the normal position. Even if the needle is significantly bent, it can be guided reliably, and since the needle guide member is connected to a needle guide drive shaft that moves back and forth linearly in accordance with the rotation of the sewing machine main shaft, machining using the feed dog is possible. To prevent the timing of needle guidance by a needle guide member from being shifted even if the cloth feed pitch of the cloth is changed.

(Example) An example of the present invention will be described below with reference to the drawings.

First, in FIG. 4, a sewing machine frame 1 includes a base 2. As shown in FIG. A support 3 is provided upright on the base 2, and an arm 4 having a jaw 4a extends horizontally from the support 3. Further, an arm portion 5 is provided on the base 2 and extends in a direction perpendicular to the arm portion 4, and its tip portion faces the jaw portion 4a from below. Furthermore, although not shown, the arm portion 4
A needle bar drive mechanism driven by the main shaft (upper shaft) of the sewing machine is disposed inside, and three needles 7, for example, are attached to a needle bar 6 that is moved up and down by this needle bar drive mechanism. Although not shown in the drawings, a cloth feed mechanism driven by a main shaft (lower shaft) 8 of the sewing machine is provided in the arm 5, and a feed dog 9 (see FIG. 1) is driven by the cloth feed mechanism. is adapted to perform cloth feeding motion in the direction of arrow A.

Now, in FIGS. 1 to 3, the needle guide device 10 includes a needle guide drive shaft 11. As shown in FIG. This needle guide drive shaft 11 is supported within the arm portion 5 by bearings 12.13 so as to be capable of linear reciprocating movement in the direction of arrow A and the opposite direction (direction of arrow B). Further, an eccentric wheel 14 is attached to the main shaft 8 of the sewing machine so as to rotate together with the main shaft 8.
A link 15 is fitted therein, and this link 15 is rotatably connected to the lower end of the adjustment lever 16.

The intermediate portion of the adjustment lever 16 is rotatably supported by a shaft 17 fixed to the base end of the arm portion 5 in the direction of arrow C and in the opposite direction (direction indicated by the arrow). And adjustment lever 1
The upper end of the adjustment lever 16 is connected to the base end of the needle guide drive shaft 11 via an adjustment link 18 and a connecting member 19. The needle guide drive shaft 11 is linearly reciprocated in the direction of arrows B and A by the reciprocating rotation in the direction of arrow B and the direction of arrow C. Furthermore, a guide holder 20 is fixed to the tip of the needle guide drive shaft 11, and a needle guide portion 21 is fixed to the needle guide holder 20 so as to be located below the feed dog 9.

As a result, the needle guide member 21 is also linearly reciprocated in the directions of arrows A and B at a position below the feed dog 9 due to the linear reciprocating movement of the needle guide drive shaft 1.

The needle guide member 21 includes a vertical surface portion 21a corresponding to each of the three needles 7 and an inclined surface portion 2 located above these portions.
1b is formed (see Figure 3).

In addition, the feed dog 9 and the needle guide member 21 at the tip of the arm 5
A looper 22 (see FIG. 6) is arranged between the three needles 7, and these loopers 22 are driven by a louver drive mechanism driven by the main shaft 8 of the sewing machine, and the needle thread is It is designed to perform a capturing movement.

Next, the operation of this embodiment will be explained with reference to FIGS. 5 to 8.

Tip, needle 7. The work cloth 2 is moved by the looper 22, feed dog 9, etc.
The principle of double chain stitching in step 3 will be described. In the state shown in FIG. 6, the needle 7 is at the lowest point, and the loop of the looper thread 24 remains caught on the needle 7. The previous loop of needle thread 25 is tightened by the downward movement of needle 7 and the balance action. In this state, when the needle 7 rises and a loop is formed in the needle thread 25, the looper 22 moves forward and its tip enters the loop of the needle thread 24, as shown in FIG. Capture this. Next, when the needle 7 rises to the highest point and begins to descend for the subsequent stitch, the looper 22 feeds the work cloth 23 while holding the loop of the needle thread 25, as shown in FIG. Start a backward movement while performing a turning movement in the opposite direction to the direction indicated by the arrow. Then, the needle 7 during the downward movement enters the triangular area formed by the tip of the looper 22, the needle thread 25 held by the looper thread 22, and the looper thread 24,
capture. Thereafter, when the looper 22 is moved further backward, the loop of the needle thread 25 comes to come off the looper 22, and the state shown in FIG. 6 is again achieved.

By the way, when the needle 7 starts its upward movement, the looper 2
2 begins to capture the needle thread 25, or at this time, the looper 22 is positioned closer to the cloth feed side than the needle 7, as shown in FIG.

Therefore, when the needle 7 bends toward the cloth feeding side due to the resistance of the work cloth 23 when penetrating the work cloth, the needle guide member 21 operates as follows in this embodiment. That is, since the needle guide drive shaft 11 is linearly reciprocated in accordance with the rotation of the sewing machine main shaft 8, it is in synchronization with the vertical movement of the needle bar 6, that is, the needle 7. Therefore, when the needle 7 starts its downward movement,
The needle guide member 21 driven by the needle guide drive shaft 11 starts moving in the direction of arrow B, which is the opposite direction to the direction of arrow A, from the cloth feed ratio side. If the needle 7 is bent toward the cloth feeding side when penetrating the work cloth 23, the corresponding vertical surface portion 21a of the needle guide member 21 is attached to the side of the bent needle 7.
The needle 7 comes into contact closely from the cloth feeding side and pushes the needle 7 back in the direction of arrow B (towards the cloth feeding side).
When the needle 7 reaches the state shown in FIG. 7, the needle 7 is guided and corrected to the normal position where it becomes vertical.

Note that when the needle 7 starts its upward movement, the needle guide member 21
starts moving in the direction of arrow A (cloth feeding side direction).

According to this embodiment, the following effects can be obtained. That is, as the needle 7 moves downward, the needle guide member 21 is moved from the cloth feeding side in the direction of arrow B, which is the opposite direction to the cloth feeding direction. Even if the needle 7 bends more than expected, it can be reliably guided and corrected to the correct position by the needle guide member 21, thereby preventing the looper 22 from colliding with the needle 7 and breaking it.
It is possible to prevent stitch skipping and thread breakage due to incomplete capture of the needle thread 25 by the needle thread 25. In addition, since the needle guide member 21 is driven by the needle guide drive shaft 11 that is linearly reciprocated in accordance with the rotation of the sewing machine main shaft 8, unlike the conventional moving system, the work cloth is moved by the feed dog 9. Even if the cloth feed pitch of 23 is changed, the timing of guiding the needle 7 by the needle guide member 21 does not shift, and therefore there is no need to adjust the position of the needle guide member 21 every time the cloth feed pitch is changed. . Moreover, since the needle guide drive shaft 11 and the needle guide member 21, which are the main components of the needle guide device 10, can be installed in the arm part 5, it is easy to install the arm part 5, which does not have much space for installation. can be implemented.

[Effects of the Invention] As explained above, the needle guide device of the double chainstitch arm sewing machine of the present invention has a needle guide drive shaft that is linearly reciprocated in accordance with the rotation of the main shaft of the sewing machine. Since the needle guide members are connected so as to move back and forth, even if the needle is bent, it can be reliably guided to the correct position, thereby preventing needle breakage or breakage.
It is possible to prevent skipped stitches and thread breakage, and even if the fabric feed pitch is changed, the timing of guiding the needle by the needle guide member does not shift, and the timing of the needle guide member is adjusted every time the fabric feed pitch is changed. This provides an excellent effect in that there is no need to perform position adjustment.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention; FIG. 1 is a longitudinal sectional view of the arm of the sewing machine frame, FIG. 2 is a cross-sectional view of the same, FIG. Perspective view of chain stitch arm sewing machine, No. 5
Figures 8 through 8 are diagrams for explaining the operation. In the drawings, 1 is a sewing machine frame, 5 is an arm, 7 is a needle, 8 is a sewing machine main shaft, 9 is a feed dog, 10 is a needle guide device, 11 is a needle guide drive shaft, and 21 is a needle guide member.

Claims (1)

[Claims] 1. In a double chainstitch arm sewing machine that performs double chainstitching on workpiece cloth using a needle, looper, feed dog, etc. that are moved based on the rotation of the sewing machine main shaft in the arms of the sewing machine frame, a needle guide drive shaft that moves back and forth linearly in accordance with the rotation of the main shaft of the sewing machine; and a needle that is connected to the needle guide drive shaft so as to move back and forth linearly at a position below the feed dog and that penetrates the work cloth and descends. A needle guide device for a double chainstitch arm sewing machine, comprising a needle guide member that approaches from the cloth feed side and guides the cloth to a proper position.