JPS5943189B2 - sewing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a seam forming means including a needle that moves up and down in order to form a seam in a workpiece disposed on a workpiece support surface; The present invention relates to a sewing machine comprising means for intermittently causing relative movement between the stitch forming means and the sewing material in synchronization with the vertical movement of the needle of the stitch forming means.

Prior Art Conventionally, in this type of sewing machine, a workpiece is held between a workpiece holder consisting of a presser foot and a feed plate, and a cam surface of a feed cam rotates in synchronization with the vertical movement of the needle. Based on the change, the machine tool holder is moved relative to the needle in the X direction and the Y direction, and a recycle pattern bartack stitch is formed by the action of the stitch forming means. there were.

When forming the cycle stitch, the first stitch l is applied to the workpiece by half a pitch while the needle moves from the top dead center to a position approximately halfway between the top dead center and the workpiece support surface. Feed is applied, and after reaching the bottom dead center, the needle that rises again passes the intermediate position and reaches the top dead center. A feed of one pitch is applied, and the upper thread is taken up based on the action of a well-known thread take-up mechanism before the first needle moves up to the intermediate position.

However, in this conventionally configured cycle sewing machine,
After the needle of the first stitch at the start of sewing reaches the bottom dead center, when it leaves the workpiece, no feed motion is applied to the workpiece, and the needle moves from the eye of the needle to the needle hole of the needle plate. The thread only extends straight through the single workpiece, and therefore, when the thread take-up mechanism is activated, the thread tends to come off from the workpiece, and there is a risk that subsequent seam formation may become impossible. there were.

The above-mentioned shedding occurred particularly frequently when a synthetic yarn was used as the needle thread.

Purpose This invention was made in order to eliminate the above-mentioned defects, and its purpose is to eliminate the first workpiece after the needle of at least the [th] stitch reaches the bottom dead center at the start of sewing. By matching the start of the relative movement of the needle to the time when the needle blade separates from the thread, flow resistance does not occur, and regardless of the type of upper thread, the needle thread can be moved at the start of sewing. Make sure to prevent the thread from coming out of the workpiece.
An object of the present invention is to provide a new sewing machine capable of reliably forming the seam.

EXAMPLE Hereinafter, an embodiment of the present invention will be described with reference to the drawings, which embodies a pattern bar-tack sewing machine which is a type of cycle sewing machine. ) supports a needle bar 3 having a needle 2 at its lower end so as to be movable up and down, and a thread loop catcher (not shown) is provided in the bed section 4 of the sewing machine body 1, and the needle 2 and thread The ring catcher and the T-twist seam forming means are constructed.

A needle plate 5 having a needle hole 5a and a lid plate 6 are respectively fixed to the upper surface of the bed portion 4, and a workpiece support surface 7 is constituted by both 5 and 6g.

On this workpiece support surface γ, a feed plate 8 having a needle insertion hole 8a and a presser arm 9 are provided, and a feed plate 10 is movably provided. The proximal end l trowel feed base 10E are each fixed.

The presser foot 11 has an opening 11a at the tip of the presser arm 9.
is supported so that it can move up and down via a holding plate 12, and when it is lowered (this is due to the spring force of the pair of compression springs 9a), the workpiece W can be held between the presser foot 11 and the feed plate 8. It has become.

Further, the feed plate 8 and presser foot 11 constitute a workpiece holder.

As shown in FIG. 2, a feed cam 14 is rotatably supported in the bed portion 4 below the feed base 10, and is synchronized with the vertical movement of the needle 2 via a gear mechanism 13 or the like. It is designed to be rotated once in one direction for each sewing cycle.

This feeding cam 14 (adjacent to this in the bed section 4 are the first and second driven arms 15, 16 and the second and second swinging arms 17, 18 with support shafts 19, 20°21.22 Each swing arm 17.1 is rotatably supported by a cylinder.
8 are connected to each of the driven arms 15 and 16, respectively.

A pair of cam grooves 14a are formed on both the front and back surfaces of the feed cam 14, and cam followers 15a and 16a projecting from one end of both driven arms 15 and 16 are formed.

Engagement parts 17a and 18a, which are respectively engaged with 14b and protrude from one end t of both swinging arms 11.
0, respectively.

Therefore, when the feed cam 14 rotates, the feed base 10 moves through the first driven arm 15 and the first swing arm 1γ according to the cam shape of the first cam groove 14a as shown in the arrows in FIGS. The cam shape of the second cam groove 14b (therefore, the feed base 10 is moved in the Y direction in FIGS. 1 and 2 via the second driven arm 16 and the second swing arm 18). will be moved.

Next, a pair of cam grooves 14a of the feed cam 14.

The structure of the cam groove 14b will be described in detail with reference to FIG. The feeding cam portion 23a
) A feed stop cam portion 23b is formed which is continuous with this and has an arc shape centered on the rotation center of the feed cam 14.

This feed imparting cam portion 23a has an angular range α1 (i=an integer from 1 to n) for imparting a half-pitch feed to the workpiece W.
and a part that has an angular range γ1 (i = an integer from 1 to n) for giving the workpiece W the feed for the remaining half pitch, and except for the part corresponding to the first stitch, both angles are The ranges αi and γ1 are set approximately equal.

Then, each time the needle 2 is moved up and down by one stitch, the feed cam 14 is rotated by a rotation angle θ in the direction of the arrow in FIG. While descending to approximately the intermediate position between The angle range β1 (i=2 to n The movement of the workpiece W is stopped by the action of the feed stop cam part 23b having an integer of i=2～
The workpiece W is moved again by the action of the feed imparting cam portion 23a having a feed rate (an integer of n).

Further, the angular range β1 of the feed stop cam portion 23b corresponding to the first stitch is set narrower than other ranges βi, and
Angular range γ of the feed imparting cam portion 23a corresponding to the first stitch
The portion having 1 is set wider than the other range γ1.

Therefore, at the first stitch at the start of sewing, the stop period of the workpiece W is shortened, and after the needle 2 descends from the top dead center to the bottom dead center, it rises from the bottom dead center and reaches the intermediate position. The movement of the workpiece W is started before, that is, around the time when the needle 2 slightly rises above the workpiece support surface 7 and separates from the workpiece W.

Next, the operation of this cycle sewing machine will be explained.

Now, when applying pattern bar tacking to the workpiece W, after raising the presser foot 11 to the upper position while the needle 2 is stopped above, the workpiece W is placed on the feed plate 8 and the presser foot 11
When the workpiece W is lowered, the spring force of the compression spring 9a causes the workpiece W to be lowered.
is held between the presser foot 11 and the feed plate 8.

In addition, during this sewing preparation time, as is clear from FIG. are combined.

When the sewing machine starts operating in this state, the needle 2 carrying the upper thread Y after the first stitch is lowered from the top dead center, and the needle 2 is moved between the top dead center and the workpiece support surface 1. While being lowered to approximately the intermediate position, based on the rotation of the feed cam 14 in the direction of the arrow in FIG. The second and second swinging arms 17 and 18 are connected to the arrows X and Y in FIG. 2 via the second driven arms 15 and 16.
Based on the swing, the feed plate 8 and presser foot 11 are moved in the directions of arrows X and Y in FIG. be done.

Next, while the needle 2 descends from the intermediate position, passes through the workpiece W, reaches the bottom dead center, and then begins to rise, the angle range β1 is based on the rotation of the feed cam 14. The feed stop cam portion 23b having the cam followers 15a, 16a
, the movement of the feed plate 8 and the presser foot 11 is stopped, and the feeding of the workpiece W is stopped.

Then, while the thread end of the upper thread Y is not restrained in any way, the needle 2
When the cam followers 15a and 16a engage the feed imparting cam portion 23a having the angle range γ1 based on the rotation of the feed cam 14, when the needles rise and the two needles separate from the upper surface of the workpiece W, the feed Board 8 and presser foot 11
is moved in the directions of arrows X and Y in Figure 1, and the
Feed for the remaining half pitch is applied to E, and the needle 2 reaches the top dead center and the sewing of the first stitch is completed.

Therefore, while the two needles are detached from the top surface of the cut workpiece W and reach the top dead center (even if the needle thread Y is picked up by the well-known thread take-up mechanism, based on the feed movement for the remaining half pinch, As shown in FIG. 4, the upper thread Y is bent and restrained between the workpiece W and the throat plate 5, and the upper thread Y is reliably prevented from slipping out.

Therefore, there is no risk of hindrance to forming the stitches after the second stitch, and even if a slippery synthetic yarn or the like is used as the upper thread Y, thread slippage will not occur.

Note that the present invention is not limited to the first embodiment. For example, the present invention is not limited to the first embodiment, and for example, a conventional lockstitch sewing machine is equipped with only a presser foot as a workpiece holder, and the workpiece W is moved by the needle based on the four-feed movement of the feed dog. It is also possible to move the workpiece W relative to 2, and as a means for causing the relative movement, it is possible to implement a sewing machine equipped with an X-Y feed device consisting of a pulse motor, etc. It is also possible to adopt a configuration in which the trowel is immovably supported on the object support surface γ, and the arm portion of the sewing machine is moved relative to the workpiece W together with the needle 2.

Effects As detailed above, the present invention provides at least the first seven stitches after the first stitch reaches the dead center at the start of sewing.
70 By aligning the start of the relative movement of the workpiece with the time at which it separates from the needle blade cutter, flow resistance does not occur, and regardless of the type of needle thread, processing at the start of sewing is possible. Reliably prevents threads from coming out of objects,
This provides an excellent effect in that the seam formation can be performed reliably.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the main parts of a cycle sewing machine embodying the present invention, Fig. 2 is a perspective view showing the coupling mechanism between the feed cam and the feed table, and Fig. 3 is an enlarged view showing a part of the feed cam. 4 is an enlarged sectional view taken along line 4--4 in FIG. 1. 2... needle, 1... workpiece support surface, 8...
...Feed plate, 11...Presser foot (this 8
, the workpiece holder is constructed from the 11th floor), 1
4... Feed cam, W... Tonichi T item.

Claims (1)

[Scope of Claims] 1. Stitch forming means including a needle 2 that moves up and down in order to form a stitch on a workpiece W disposed on a workpiece support surface 7;
. Means 8, 11, and 14 are provided for intermittently causing relative movement between the stitch forming means and the 770 workpiece W in synchronization with the vertical movement of the needle 2 of the stitch forming means. In this sewing machine, the first relative movement after the needle 2 of the first stitch reaches the bottom dead center at the start of sewing is set to be around the time when the needle 2 leaves the 7711 workpiece W. A sewing machine characterized in that it is made to match. 2. The means for producing the relative movement includes a workpiece holder 8.11 for holding the workpiece W, and a feed cam for moving the workpiece holder 8, 11 relative to the needle 2. 14. The sewing machine according to claim 1, wherein the sewing machine includes a feed cam 14, and the start timing of the relative movement is set based on the shape of the feed cam 14.