JPS5818852Y2 - Sewing machine cloth feed control device - Google Patents

Description

[Detailed description of the invention] The present invention relates to a cloth feeding device of a sewing machine, and uses a drive source different from the upper shaft drive of the sewing machine to perform the vertical movement and/or horizontal movement of the feed dog, and electronically controls the driving. By doing so, the feed dog is controlled so that it always operates in the vicinity of the needle drop point of the fabric, regardless of the feed control amount.

When performing sewing work using a sewing machine, there are many problems caused by the fabric feed phase.

Examples of this are the so-called thread failure, where the cloth feed operation begins before the thread is fully aligned, and the cloth feed operation that does not complete even when the needle reaches the cloth when sewing thick materials. There may be needle breakage, etc.

In addition, in parallel with needle lateral runout control, the fabric feed amount is controlled for each stitch, and a manual feed adjuster is used to adjust the feed amount to an arbitrary value, but these controls are usually effective against the fabric of the feed dog. Equal distribution relative to the center of the operating range, that is, the range where the feed dog is above the throat plate surface and horizontally feeds, is achieved by adjusting the amount.

Fig. 1 is a diagram related to the feed dog, and of the three integrated feed dogs 1, 2.3, the center feed dog 1 will be explained below.The feed dog 1 shown by the solid line is within the effective operating range. This is the state in which it has moved furthest to the front, and 1', indicated by a chain line, is the state in which it has moved to the furthest rear.

C1 indicates the center of both of these states, that is, the horizontal feeding range, C2 is the center of the feed dog 1 shown by a solid line, and C3 is the center of the feed dog 1' shown by a chain line.

The distance 11 between each center C2 and C3 is distributed around C1 and indicates the horizontal feed amount, and the above-mentioned cloth feed control and its manual adjustment are to control and adjust this distance 11, and the control and adjustment are performed by the needle. This is because the distance 12 between the plate needle hole 4 and the end of the feed dog 1 is changed.

That is, when the horizontal feed is maximum (11 maximum), the distance 12 is the minimum, and when the horizontal feed is the minimum (11 is 0), the distance 12 is the maximum.

Normally, zigzag sewing machines have three feed teeth 1, 2.3 as shown in Figure 1, but when sewing the edges of cloth, two feed teeth including the center feed dog 1 are effective. The other one strip often comes off the cloth and becomes invalid.

When the distance 12 is minimum, the operation start point of the feed dog 1 is close to the needle drop point, and there is no problem.As the feed amount becomes smaller, as the distance 12 becomes larger, the operation start point of the feed dog 1 is closer to the needle drop point. For example, when feeding the cloth using feed dogs 1 and 2, the material moves away from the falling point, and problems such as imbalance in the feeding functions of both feed dogs and expansion/contraction of the cloth affect the amount of cloth feed, resulting in irregular stitches. It had the disadvantage of causing

In addition, in order to eliminate this problem, so-called offset systems have been used to control the operating range of the feed dog, in which the center of the operating range is structurally moved without moving the operating range. However, due to the structure, there is a limit to the production accuracy of the related moving parts, and there are also problems such as the feeding mechanism being agitated especially when rotating at high speed due to the large moment of inertia of the mechanical part. It is in a state where it is not widely adopted.

The present invention is a device devised in view of these circumstances, and uses a drive source separate from the drive source for the upper shaft or lower shaft to drive the vertical movement and horizontal movement of the feed dog, or one of them. The phase relationship is controlled based on electronic memory to ensure the timing of needle movement and cloth feed is appropriate, and to ensure that the feed dog always operates near the needle drop point, the horizontal movement of the feed dog is used to control the feed amount. Even if the range changes, the starting point of the cloth feed operation will always remain near the needle.
To explain this embodiment with reference to drawings, FIG.
This shows an example of control using a pulse motor to drive the feed shaft.

In the figure, solid arrows indicate the relationship and direction of electrical signals, and chain lines indicate mechanical relationships.

The ROM is a read-only electronic storage device that stores stitch control signals and program control signals.

The CPU is a central processing unit that issues read instructions for the storage device, controls various programs, performs arithmetic processing, and the like.

The RAM is an electronic temporary storage device that operates according to instructions from the arithmetic processing unit and temporarily stores the contents of the storage device ROM, data necessary for various operations, or operation results.

Each of these storage devices ROM, RAM and arithmetic processing unit C
PU constitutes a microcomputer. SM is a sewing machine motor, which is driven by a sewing machine motor drive circuit DVs controlled by a controller CONT, and drives an upper shaft (not shown) of the sewing machine.

An upper shaft sensor NS is attached to the upper shaft of the sewing machine, and the sensor is adapted to generate pulses at predetermined phases of the vertical movement of the needle.

PG is an upper shaft rotation proportional pulse generator, which is similarly attached to the upper shaft, and while the upper shaft sensor NS generates one pulse per upper shaft rotation 2π as shown in Fig. 3, it generates multiple pulses. The generated pulse is the upper axis sensor N
The arithmetic processing unit CPU detects the upper shaft rotation phase by counting the number of pulses after S is switched to the high H or low L level.

The switching point from the L level to the H level (0 or 2π) and the switching point from the H level to the L level (π) of the upper axis sensor NS are respectively located at the needle plate (both not shown).
The extraction on the surface is made to match the phase when it is about to enter immediately after exiting.

PS is a pattern selection device that provides a code for specifying the pattern to be selected by this operation to the arithmetic processing unit CPU.

MR is a manual feed amount adjuster, and the adjuster is converted into a digital amount by an analog-to-digital converter (A/D) and provided to the arithmetic processing unit CPU.

DVp is a pulse motor drive circuit, and the processing unit CPU
The storage device ROM controls the drive of the pulse motor PM at a specific upper axis phase for each stitch by the control signal of Each date that determines the feed end phase is memorized, and the pulse motor P
In order to drive control M in relation to the upper axis phase, the arithmetic processing unit CPU determines the levels H and L of the upper axis sensor NS in FIG. The upper shaft rotation phase is designated based on the combination with the number of pulses of the upper shaft rotation proportional pulse generator PG counted while switching to L.

The drive speed (sewing machine upper shaft rotation and relative speed) and its control amount are determined by the arithmetic processing CPU designating some of the upper shaft rotation proportional pulses PG in Fig. It is determined by how many driving pulses are allocated to each.

MS is a pulse motor rotational position sensor, which is mainly used as an initial reset position sensor for the pulse motor PM.

FIG. 4 is a schematic diagram for explaining the operation of the feed mechanism driven by the control device shown in FIG.

Reference numeral 7 denotes a horizontal feed table, with a rack 8 provided below, which meshes with a pinion 10 attached to a horizontal feed shaft 9 pivotally connected to the sewing machine body, and moves from side to side in the figure by reciprocating rotation of the shaft. It looks like this.

The horizontal feed table 7 is fitted with the vertical feed table 5 so as to be able to move up and down, and a cam engagement plate 11 is attached to the horizontal feed table. The vertical movement is caused by a vertical feed cam 13 attached to a vertical feed shaft 12 that rotates in synchronization with the vertical feed shaft 12.

The horizontal feed shaft 9 is reciprocated by a pulse motor PM shown in FIG.

14 is a needle bar, and 15 is a presser bar. Next, the operation of the above configuration will be explained.

Referring to the flowchart in Figure 5, turn on the control power (ON).
Then, the microcomputer centered around the arithmetic processing unit CPU becomes operational, and the pulse motor PM is excited and set to the initial position.

This initial reset can be carried out in detail, for example, in Japanese Patent Application No. 53-27951 (Japanese Unexamined Patent Publication No. 54-120816) filed by the same applicant as the present application.

That is, by rotating the pulse motor PM in one direction, the feed teeth 1 to 3 in FIG. Further, the feed dog is stopped at a phase in which the feed dog is below the throat plate surface (not shown).

This operation is performed when the upper axis sensor NS in FIG. 3 is at H level.

Then, a data counter for advancing data reading for each stitch, which will be described later, is reset.

When the pattern selection device PS is operated, each stitch control signal group constituting the pattern is specified, and from among the groups, the cloth feed position coordinates (of the pattern) specified by the reset data of the data counter are selected. Each tag is read indicating the feed coordinate (0) for the first stitch and the feed position coordinate for the next stitch.

Then, it is determined whether the feed of the stitch to be executed in the pattern calculated from these two data is to move the feed dogs 1 to 3 forward or backward.

When the sewing machine rotates and detects that the upper shaft sensor NS is at the L level in Fig. 3, this indicates that the feed teeth 1 to 3
is the phase in which horizontal feed is to be performed below the throat plate surface in preparation for cloth feeding, that is, the set phase, and if the pulse motor PM is driven, and the above determination is forward movement, the initial position of forward movement, that is, the length 12 in FIG. The feed dog is stopped at the feed dog position shown by the solid line where is the minimum.

When the sewing machine rotates further, the cam 13 causes the feed dogs 1 to 3 to
moves above the throat plate surface and detects that the upper shaft sensor NS is at the H level. This indicates the phase in which horizontal feed should be performed above the throat plate surface as an operation to perform cloth feeding by performing feed diagrams 1 to 3. This is the feed phase, and the pulse motor PM is driven, horizontally moved by the calculated feed amount, and then stopped.

A pulse counter counts the pulses of the upper shaft rotation proportional pulse generator PG, and the result is sent to the arithmetic processing unit CPU.
This is because a pulse motor stop command is given to the pulse motor drive device ypvp when the value matches the calculation result.

Next, the data counter is incremented by 1 and the process returns to the next step of resetting the data counter to execute the routine for the next stitch.

If the determination based on the calculation result specifies reverse movement, when it is detected that the feed dog set phase, that is, the upper axis sensor NS is at the L level, the feed dog feed amount to be executed from now on is determined based on the calculation result. For example, it is moved to the position indicated by the chain line in FIG. 1 on the lower surface of the throat plate.

This is the reverse initial position, and while the forward initial position is the fixed position of the feed dog, this is a variable position that is moved from this fixed position by the calculated amount.

In the feed phase, the control is similar to that in the forward movement, but the direction of movement of the feed teeth 1 to 3 is reversed, and the feed teeth stop at the position shown by the solid line in FIG.

As described above, according to the present invention, the feed dogs 1 to 3 move horizontally while always keeping the distance 12 from the needle hole to the minimum regardless of the feed amount, so the cloth is fed appropriately and there is no risk of pattern distortion. This has a great practical effect.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of the vicinity of the feed dog, Fig. 2 is a block diagram of a control circuit showing an embodiment of the present invention, Fig. 3 is an explanatory diagram of the upper shaft phase signal, and Fig. 4 is a diagram of the feed mechanism section. The schematic diagram, FIG. 5, is a flowchart of the control. In the figure, 1.2.3 is the feed dog, 4 is the needle drop, the pulse motor PM is the feed mechanism drive source, the upper shaft sensor NS and the upper shaft rotation proportional pulse generator PG are the upper shaft phase signal generator, and the arithmetic processing unit. The CPU is the main element of the control section.

Claims (1)

[Scope of utility model registration request] Different from the upper shaft drive, there is an independent feed mechanism drive source, an upper shaft phase signal generator that generates an output signal related to the rotational phase of the upper shaft, and the feed mechanism in relation to the signal of the phase signal generator. a control section for controlling a mechanism drive source, the control section having a memory of data relating to cloth feeding for each stitch and a calculation function thereof, and a feed dog for controlling the cloth feeding operation for each stitch. For forward feed, it is the horizontal position closest to the needle drop, and for backward cloth feed, it is a position horizontally moved by the amount of backward feed to be executed from the horizontal position based on the storage of the data and its calculation. A cloth feed control device for a sewing machine, characterized in that each initial value is set as nothing.