HK1228971B - Needle plate replacement device with lock - Google Patents

Description

Needle plate changer with lock

Technical Field

The present invention relates to a needle plate replacement device for disassembling and installing a needle plate of a sewing machine at a base portion of a machine casing, and in particular to a needle plate replacement device with a lock that can prevent the installed needle plate from accidentally falling off.

Background Art

Inside the base of the sewing machine where the needle plate is installed, there are housed a lower shaft that is synchronized with the upper shaft that drives the needle, and a needle cylinder and other needle thread catching mechanisms or feeding mechanisms that are linked to the above-mentioned lower shaft. In order to carry out maintenance of the sewing machine such as responding to failures of these linked mechanisms, it is sometimes necessary to disassemble and assemble the above-mentioned needle plate.

In addition, the needle plate may need to be replaced with a different needle plate depending on the sewing purpose, such as straight sewing or zigzag sewing.

Since the needle plate has a needle hole through which the needle passes, the needle hole must be correctly positioned at the position where the needle falls when the needle plate is installed on the sewing machine. Therefore, the needle plate needs to be correctly aligned with the casing of the sewing machine for installation.

To address this issue, a needle plate disassembly mechanism that is easy to assemble and disassemble is currently known. The needle plate disassembly mechanism has an opening mechanism that allows the installed needle plate to be easily removed without the need for tools such as a screwdriver, and can be positioned and fixed by simple operations during installation (for example, refer to patent document 1).

Prior art literature

Patent Literature

Patent Document 1: Japanese Patent Application Laid-Open No. 2013-48846

Problems to be solved by the invention

However, when using a sewing machine, the upper or lower thread may become tangled due to some unforeseen circumstances. In such cases, the thread may become entangled with the inner cylinder inside the needle plate, causing the sewing machine to lock and the inner cylinder to fly out. The flying inner cylinder may push up the needle plate, creating an extremely dangerous situation.

In addition, in the needle plate disassembly and assembly mechanism described in the above-mentioned patent document 1, if the needle plate bulges or falls off, the needle plate detection switch will detect that the needle plate has fallen off. Therefore, although the sewing machine stops driving safely, if the needle plate falls off, the inner cylinder will fly out, and there is a risk that the needle will pierce the inner cylinder or the needle will break.

In addition, the needle plate is held on the base by the force of the needle plate spring. Therefore, the more the inner cylinder is suppressed from flying out, the weaker the holding force of the needle plate spring becomes. If the inner cylinder is to be suppressed from flying out, the holding force of the needle plate spring must be increased to a level higher than necessary, which requires additional force for assembly and disassembly, posing a practical problem.

Summary of the Invention

The present invention aims to solve the above-mentioned problems, and its purpose is to provide a needle plate replacement device with a lock, wherein when the needle plate is installed on the base part, the needle plate can be reliably locked to the base part through a simple operation, and when the needle plate is removed from the base part, the locking state can be released with a simple single-action operation, and the needle plate can be lifted from the base part.

Technical solutions to problems

In order to solve the above-mentioned problems, the present invention adopts the following structure, that is, as a needle plate replacing device with a lock, a needle plate replacing device with a lock is provided, which is capable of detaching and installing a needle plate on a base portion of a sewing machine, and is characterized in that it comprises: a positioning mechanism, which is provided on the base portion and the needle plate and is interlocked with each other to position the needle plate in the installation position of the base portion; a locking mechanism, which has a locking part provided on the base portion and a locked part provided on the needle plate, and by installing the needle plate in the installation position of the base portion, the locking part and the locked part are locked and maintained in the locked state; a lifting mechanism, which is provided on the base portion and lifts the needle plate installed on the base portion to a disassembly position above the base portion; and a releasing mechanism, which is linked to the operation of the lifting mechanism to release the locking state of the locking part and the locked part of the locking mechanism.

As a specific embodiment of the locking mechanism of the present invention, the following structure is adopted, which is characterized in that the locking component of the locking mechanism includes a hook-shaped locking claw portion that is reciprocally arranged on the base portion and a locking spring that applies force to the locking claw portion in a locking direction, and the locked component of the locking mechanism includes a locking support plate that hangs down from the lower surface of the needle plate and is locked with the locking claw portion.

As a specific embodiment of the release mechanism and the lifting mechanism of the present invention, the following structure is adopted, which is characterized in that the release mechanism includes a release component provided on the lifting mechanism and an action component provided on the locking claw portion and engaged with the release component to enable the locking claw portion to move against the force direction. In addition, the following structure is adopted, which is characterized in that the lifting mechanism includes: a needle plate replacement lever, which is rotatably pivoted to the base portion; a needle plate replacement rod, which pushes the bottom of the needle plate upward through the operation of the needle plate replacement lever to lift the needle plate to the disassembly position above the base portion; and a return spring, which applies force to the needle plate replacement rod downward.

As an embodiment of the needle plate replacement device with locking of the present invention, the following structure is adopted, which is characterized in that it also has a holding mechanism for holding the needle plate in the installation position of the base part, and the holding mechanism includes a needle plate spring with a curved portion provided on the lower surface of the needle plate and a locking vertical wall provided on the base part and forming an embedding portion in which the curved portion of the needle plate spring is embedded.

As a specific embodiment of the holding mechanism of the present invention, the following structure is adopted, which is characterized in that the holding mechanism also has a locking component for locking the needle plate at the installation position of the base part, and the locking component includes: a fixing plate, which is provided on the lower surface of the needle plate on the side opposite to the needle plate spring; and a support plate, which is provided on the base part, clamps the front end portion of the fixing plate between the support plate and the upper support wall of the base part, and can hold the needle plate in a rotatable manner at a specified angle.

Effects of the Invention

The needle plate replacing device with a lock of the present invention comprises: a locking mechanism, wherein only by pressing the needle plate against the base portion, the positioning mechanism can align the needle plate to the mounting position of the base portion, and the locking member provided on the base portion is locked and maintained in the locked state; a lifting mechanism, which lifts the needle plate mounted on the base portion to the removal position above the base portion; and a releasing mechanism, which is linked to the operation of the lifting mechanism to release the locking state of the locking member and the locked member of the locking mechanism. Therefore, no other tools such as a screwdriver are required. Not only can the needle plate be mounted on the base portion to the locked state by a simple operation, but also, when the needle plate is removed, the locking state of the locking member and the locked member can be released in conjunction with the operation of the lifting mechanism, and the needle plate can be pushed up to the removal position above the base portion, thereby preventing the needle plate from unexpectedly rising.

The locking member of the locking mechanism includes a hook-shaped locking claw portion which is reciprocally provided on the base portion and a locking spring which urges the locking claw portion in the locking direction, and the locked member of the locking mechanism includes a locking support plate which is suspended from the lower surface of the needle plate and is locked with the locking claw portion. Therefore, when the needle plate is pressed into the installation position of the base portion, the front end of the locking claw portion temporarily moves to the side opposite to the locking direction by abutting against the lower end of the locking support plate, and then locks with the locking support plate. Therefore, when the needle plate is installed to the base portion, the locking claw portion can be locked with the locking support plate by only pressing it from above, thereby locking the needle plate.

The cam is secured to the base portion by a spring which pushes the bottom of the needle plate upward and pushes the needle plate to the disassembly position above the base portion when the cam is operated. The cam is secured to the base portion by a spring which pushes the bottom of the needle plate upward and pushes the needle plate to the disassembly position above the base portion when the cam is operated. The cam is secured to the base portion by a spring which pushes the bottom of the needle plate upward and pushes the needle plate to the disassembly position above the base portion when the cam is operated.

BRIEF DESCRIPTION OF THE DRAWINGS

1 is an overall perspective view of a sewing machine according to an embodiment of the present invention;

2 is an exploded perspective view of a free arm portion of a sewing machine with a top cover removed according to an embodiment of the present invention;

3 is a perspective view showing a state when the needle plate according to the embodiment of the present invention is mounted on the base portion;

4 is a top view showing the vicinity of a support plate into which one end portion of a needle plate is embedded according to an embodiment of the present invention;

FIG5(a) is a front view of a needle plate of a sewing machine according to an embodiment of the present invention, and (b) is a bottom (back) view thereof;

FIG6 (a) is a partially cutaway front view showing a state in which a needle plate of a sewing machine according to an embodiment of the present invention is mounted on a base portion, and FIG6 (b) is an enlarged view showing a main portion near a support plate into which one end portion of the needle plate of FIG6 (a) is embedded;

FIG7 (a) is an enlarged front view showing a state in which the front end portion of the needle plate spring abuts against the tapered portion of the engaging wall when the needle plate of the sewing machine according to the embodiment of the present invention is mounted on the base portion; FIG7 (b) is an enlarged front view showing a state in which the contact portion of the locking support plate abuts against the inclined portion of the locking claw;

FIG8(a) is an enlarged front view showing a state in which a locking claw portion rotates against the elastic force of a locking spring when the needle plate of a sewing machine according to an embodiment of the present invention is mounted on a base portion; FIG8(b) is a partially cutaway front view showing a state in which the needle plate is mounted and locked on the base portion;

Figure 9 (a) is an enlarged front view showing the state in which the needle plate of the sewing machine according to an embodiment of the present invention is removed from the base, and the needle plate replacement rod is pushed up to release the locking claw portion, and (b) is an enlarged front view showing the state in which the needle plate replacement rod pushes the bottom of the needle plate upward.

Description of Reference Numerals

M sewing machine

1 Upper frame

2 Column

3 arms

4. Base

5. Base of the base

6 Free arms

7 Top cover

8 needle plate

8a Pinhole

9-pin

10 Needle plate replacement lever

11 Needle plate replacement rod

12, 13 pallets

12a, 13a tableting

14, 15 snap-fit wall

14a, 15a Embedded portion

14b, 15b cone

16 Locking claw

17 Guide pin

18 positioning pins

20 Upper supporting wall

21, 22 fixing plates

23, 24 screws

25 Insert guide surface

26 Introduction

27 Guide slot

28 positioning holes

29 Parallel guide surfaces

30 tapered guide surface

31, 32 needle plate spring

31a, 32a curved portion

31b, 32b front end

33 Locking the pallet

33a Locking hole

33b contact part

34 axis

35 Mounting plate

36 locking claws

36a Inclined surface

37 Action Arm

38 Connection

39 Locking spring

40 Action Pins

41 Release pin

42 bottom wall

43 Pivot

44 hook protrusion

45 lower end

46 abutment

47 Lower support wall

48 return spring

DETAILED DESCRIPTION

Hereinafter, a sewing machine equipped with a needle plate replacing device with a lock according to an embodiment of the present invention will be described with reference to the accompanying drawings showing embodiments.

Example

In FIG. 1 , reference numeral 1 denotes an upper frame of a sewing machine M equipped with a needle plate replacing device, and the upper frame is composed of a column portion 2 and an arm portion 3 extending leftward from the column portion 2 .

Reference numeral 4 denotes a base portion of the sewing machine M, which is composed of a base portion 5 and a free arm portion 6 extending cylindrically from the base portion 5 .

Reference numeral 7 denotes a top cover covering the upper opening of the free arm portion 6 , and reference numeral 8 denotes a needle plate detachably mounted on the upper surface of the free arm portion 6 as will be described later.

The needle bar having the needle 9 attached to the front end is driven in the vertical direction from the arm portion 3 of the upper frame 1 so that the needle 9 is driven to be inserted into the needle hole 8a of the needle plate 8 ( FIG. 5 ).

As shown in Figures 1 to 3, reference numeral 10 is a needle plate replacement lever provided at the lower portion of the free arm portion 6 of the base portion 4, which operates a needle plate replacement rod 11 for lifting the lower surface of the needle plate 8.

On the upper part of the free arm 6, there are support plates 12, 13 for installing and holding the needle plate 8, engaging vertical walls 14, 15, a locking claw 16 for locking the installed and held needle plate 8, a guide pin 17 for positioning when installing the needle plate 8, a positioning pin 18, etc., which are respectively supported by the upper support wall 20.

As shown in FIG. 2 to FIG. 5 , the needle plate 8 is provided with fixing pieces 21 and 22 that protrude in the lateral direction from one end side of the lower surface.

The support plates 12 and 13 corresponding to the fixing plates 21 and 22 are fixed to the upper surface of the upper support wall 20 of the free arm 6 by screws 23 and 24 respectively, and pressing plates 12a and 13a are formed at the ends of the support plates 12 and 13 and are erected upward at a specified angle.

When the needle plate 8 is mounted on the base 4, the fixing pieces 21 and 22 of the needle plate 8 are respectively inserted between the pressing pieces 12a and 13a and the upper surface of the upper support wall 20, so that they function as a locking mechanism.

As shown in FIG. 4 , one support plate 13 is provided with an introduction portion 26 having opposing insertion guide surfaces 25 at a slightly wider interval than the fixing piece 22 on both sides of the pressing piece 13 a.

The needle plate 8 has a long guide hole 27 near one end where the fixing pieces 21 and 22 are provided, and a positioning hole 28 farther from the end (near a position where the needle plate replacement rod 11 is pushed up, as will be described later).

4 and 5 (b), the guide long hole 27 has a parallel guide surface 29, when the needle plate 8 is installed, the guide pin 17 is engaged with the guide long hole 27 and can slide along the parallel guide surface 29.

As shown in Figure 7, the positioning hole 28 has a tapered guide surface 30 that extends into a mortar shape toward the bottom of the needle plate 8. When the needle plate 8 is installed, the positioning pin 18 first connects with the tapered guide surface 30 and is guided toward the center of the positioning hole 28. When it is fully engaged with the positioning hole 28, the final positioning is completed. They act as a positioning mechanism.

As shown in FIG3 and FIG5 (a), on the needle plate 8, needle plate springs 31, 32 are provided on the lower surface of the side opposite to the one end side where the fixing pieces 21, 22 are provided. The needle plate springs 31, 32 form bent portions 31a, 32a and hang downward.

As shown in Figure 8(b), when the needle plate 8 is installed, the bent portions 31a, 32a of the needle plate springs 31, 32 respectively engage with the embedded portions 14a, 15a (refer to Figure 3) of the engaging walls 14, 15, and act as a holding mechanism that maintains the holding state of the needle plate 8 by its elastic force.

In addition, in this embodiment, the embedded parts 14a and 15a are holes that pass through the engaging upright walls 14 and 15, but they do not necessarily have to be through holes, and can also be cut-out recesses, etc., as long as the bent parts 31a and 32a are embedded and can be engaged by elastic force.

As shown in Figures 2 and 3, by providing tapered portions 14b and 15b at the upper ends of the engaging walls 14 and 15, respectively, when the needle plate 8 is pressed down during installation, the bent portions 31a and 32a or the front ends 31b and 32b of the needle plate springs 31 and 32 slide into the tapered portions 14b and 15b, respectively, making it easy for them to engage with the embedded portions 14a and 15a.

As described later, when needle plate 8 is removed from base 4 , bent portions 31 a , 32 a or distal ends 31 b , 32 b of needle plate springs 31 , 32 are supported by tapered portions 14 b , 15 b , respectively, to maintain needle plate 8 in the removed state.

As shown in FIG. 3 , the needle plate 8 is provided with a locking bracket 33 suspended from its lower surface. The locking bracket 33 is formed with a locking hole 33 a.

The upper support wall 20 is provided with a mounting plate 35 suspended from an end thereof and having a horizontal support shaft 34 planted thereon.

The lock claw portion 16 includes a hook-shaped locking claw 36 extending upward and an operating arm 37 extending in the lateral direction. The locking claw 36 and the operating arm 37 are connected by a U-shaped connecting portion 38 .

The connection portion 38 of the locking claw portion 16 is rotatably pivotally connected to a support shaft 34 implanted in the mounting plate 35 , and a locking spring 39 is provided between the locking claw 36 and the mounting plate 35 .

The locking claw 16 is urged by the elastic force of the locking spring 39 to rotate in a direction (counterclockwise in Figures 6 to 9) in which the locking claw 36 is locked with the locking hole 33a of the locking bracket 33, thereby functioning as a locking mechanism.

In addition, in this embodiment, a locking hole 33a is formed on the locking support plate 33, but it is not necessary to form the locking hole 33a on the locking support plate 33. The longitudinal cross-section of the lower end of the locking support plate 33 can also be L-shaped, etc., as long as the locking claw 36 can be locked to the lower end of the locking support plate 33.

In addition, in this embodiment, the locking claw portion 16 is rotatably pivotally connected to the support shaft 34 planted on the mounting plate 35, but it is not necessarily necessary for the locking claw portion 16 to be rotatably pivotally connected. The locking claw portion 16 can also slide relative to the upper support wall 20 as long as it can move back and forth in the direction of being locked on the locking support plate 33.

At the end of the action arm 37 serving as the action component of the locking claw portion 16, an action pin 40 is planted parallel to the support shaft 34. The action pin 40 engages with a release pin 41 serving as a release component that protrudes horizontally from the middle of the needle plate replacement rod 11 to prevent further rotation of the action arm 37 that is biased in the locking direction by the elastic force of the locking spring 39. They act as a release mechanism.

In addition, in this embodiment, an operating arm 37 is provided on the locking claw portion 16 as an actuating component, and a release pin 41 is provided on the needle plate replacement rod 11 as a release component, but the operating arm 37 and the release pin 41 are not necessarily required. A cam surface, etc. can be provided in the middle part of the needle plate replacement rod 11 as a release component, and a follower, etc. can be provided on the locking claw portion 16 as an actuating component. As long as the release component is linked with the lifting of the needle plate replacement rod 11, the locking claw portion 16 can be actuated against the direction of the applied force.

As shown in FIG2 and FIG3, at the lower portion of the free arm portion 6 of the base portion 4, a needle plate replacement lever 10 is pivotally mounted on the bottom wall 42 via a pivot 43 provided along the longitudinal direction of the free arm portion 6.

The needle plate replacement lever 10 is provided with a finger-hooking protrusion 44 at the end portion closer to the front side than the pivot 43, for the operator to hook his finger and press downward in front, and an abutment portion 46 is provided on the rear side of the pivot 43 on the opposite side of the finger-hooking protrusion 44, which is connected to the lower end portion 45 of the needle plate replacement rod 11 to move the needle plate replacement rod 11 up and down.

The needle plate replacement rod 11 is urged downward by the return spring 48 supported by the lower support wall 47 of the free arm 6, and the upper end of the needle plate replacement rod 11 lifts up the side of the needle plate 8 opposite to the end side where the fixing plates 21 and 22 are provided, and the lower end portion 45 of the needle plate replacement rod 11 is always in contact with the abutment portion 46 of the needle plate replacement lever 10, and they act as a lifting mechanism.

Next, the usage and effects of this embodiment are described.

As shown in Figure 6, in order to install the needle plate 8 on the base 4, first, the front ends of the fixing plates 21 and 22 provided on one end side of the needle plate 8 are slid from the front of the support plates 12 and 13 to the top of the upper support wall 20, and the fixing plate 22 on one side is slid along the insertion guide surface 25 of the introduction part 26 provided on the support plate 13 on the same side, so that it is embedded between the pressing plate 13a and the upper fixing surface formed on the top of the upper support wall 20.

As shown in FIG. 4 , the insertion guide surfaces 25 are spaced apart from each other at a distance slightly larger than the width of the fixing pieces 22 and face each other, guiding the front ends of the fixing pieces 21 and 22 to fixed positions, thereby achieving the initial positioning function of positioning one end of the needle plate 8 .

The introduction portion 26 having the insertion guide surface 25 can also be provided on the other side of the support plate 12, but the operability may not be good when two introduction portions 26 that are required to be correctly embedded are provided, and from a cost perspective, it is preferably provided on either side of the support plates 12, 13.

The pressing pieces 12a and 13a are formed with inclined surfaces rising upward at a predetermined angle, and the fixing pieces 21 and 22 embedded between the inclined surfaces and the upper surface of the upper support wall 20 are held so as to be rotatable at a predetermined angle around an imaginary rotation axis formed by their front ends.

The imaginary rotation axis formed by the front ends of the fixing plates 21 and 22 is roughly consistent with one end of the fixed position by inserting the guide surface 25 and the pressing plates 12a and 13a. Therefore, if the needle plate 8 is pressed downward from the upper side opposite to the end side where the fixing plates 21 and 22 are provided in the direction of the arrow shown in Figure 6(a) by pressing toward the upper part of the base portion 4, the guide pin 17 can first be easily engaged with the guide long hole 27 provided relatively close to the fixing plates 21 and 22 of the needle plate 8.

When the needle plate 8 is further pressed down, as shown in FIG. 7( a ), the tip of the positioning pin 18 comes into contact with the positioning hole 28 provided relatively far from the fixing pieces 21 , 22 .

If the needle plate 8 is further pressed down from this state, as shown in FIG. 7( b ), the needle plate 8 moves in accordance with the trajectory of the contact point between the needle plate 8 and the tapered guide surface 30 so that the centers of the positioning pins 18 and the positioning holes 28 coincide with each other.

At this time, as shown in Figure 4, since a parallel guide surface 29 roughly perpendicular to the above-mentioned imaginary rotation axis is formed in the guide long hole 27, as the positioning pin 18 is engaged with the positioning hole 28, the guide pin 17 can slide along the parallel guide surface 29 of the guide long hole 27 to guide the needle plate 8 to the correct fixed position.

In this way, the guide long hole 27 and the positioning hole 28 are respectively engaged with the guide pin 17 and the positioning pin 18, and the final positioning is completed through mutual cooperation. Therefore, it is preferred that they are separated from each other in a direction parallel to the above-mentioned imaginary rotation axis, and preferably not arranged on the same line perpendicular to the imaginary rotation axis.

7 (a) , the front ends 31b, 32b of the needle plate springs 31, 32 provided at the lower portion of the needle plate 8 come into contact with the tapered portions 14b, 15b formed at the upper ends of the engagement walls 14, 15.

Furthermore, if the needle plate 8 is further pressed, as shown in FIG. 7( b ), the bent portions 31 a , 32 a of the needle plate springs 31 , 32 elastically deform while sliding in contact with the tapered portions 14 b , 15 b and moving downward.

At the same time, the locking support plate 33 provided on the lower surface of the needle plate 8 abuts against the inclined surface 36a formed on the upper part of the locking claw 36 through its contact portion 33b, as shown in Figure 8(a), causing the locking claw portion 16 to rotate in the clockwise direction against the direction of the elastic force of the locking spring 39.

If the needle plate 8 moves to the place where the center of the positioning hole 28 coincides with the center of the positioning pin 18 through the tapered guide surface 30, the positioning hole 28 and the positioning pin 18 are completely fitted together, the needle plate 8 is positioned and is installed on the fixed surface of the base portion 4.

8 (b), the needle plate springs 31, 32 of the bent portions 31a, 32a are embedded in the engagement portions 14a, 15a of the vertical walls 14, 15, and the needle plate 8 can be held in a fixed position at the base portion 4 by its elastic force.

At the same time, the locking claw 36 of the locking claw portion 16 is locked with the locking hole 33a formed in the locking bracket 33, so that the needle plate 8 held at the fixed position of the base portion 4 can be locked.

Thus, in this embodiment, when the needle plate 8 is installed on the base portion 4, only the fixing pieces 21, 22 provided on one end side of the needle plate 8 are inserted into the support plates 12, 13, and pressed down from above the side opposite to the end side provided with the fixing pieces 21, 22, so that the needle plate 8 can be positioned and installed and fixed. Through a simple installation operation, the needle plate can be firmly locked and put into a locked state to prevent the installed needle plate from unexpectedly rising.

Next, an operation of releasing the locked state of attached needle plate 8 and pushing it up to the removal position above base 4 to remove needle plate 8 from base 4 will be described.

As shown in Figure 3, the needle plate replacement lever 10 is mounted on the lower part of the base part 4 through the pivot 43. In the non-operating state where the needle plate 8 is mounted in a fixed position, the abutment portion 46 near the end portion on one side of the needle plate replacement lever 10 relative to the pivot 43 is pressed down by the lower end portion 45 of the needle plate replacement rod 11 which is urged downward by the elastic force of the return spring 48. Therefore, the hook protrusion 44 provided at the end portion on the other side of the needle plate replacement lever 10 relative to the pivot 43 is accommodated along the outer periphery of the bottom wall 42 of the base part 4.

When removing the needle plate 8, if you hook your fingers on the finger hook protrusion 44 of the needle plate replacement rod 10 and press it down, the needle plate replacement rod 10 will rotate counterclockwise in Figure 3 around the pivot 43, and the abutment portion 46 will rise inside the base portion 4, pushing up the lower end portion 45 of the needle plate replacement rod 11 against the elastic force of the return spring 48.

As shown in Figure 9(a), when the upper end of the needle plate replacement rod 11 is lifted up to just before it abuts against the lower surface of the needle plate 8 by pressing down the needle plate replacement lever 10, the release pin 41 protruding from the middle of the needle plate replacement rod 11 lifts the action pin 40 of the action arm 37 planted in the locking claw portion 16, causing the locking claw portion 16 to rotate clockwise against the elastic force of the locking spring 39.

By the rotation of the locking claw portion 16 , the locking claw 36 is disengaged from the locking hole 33 a of the locking bracket 33 , and the needle plate 8 attached to the base portion 4 is unlocked.

Furthermore, by pressing down needle plate replacement lever 10, needle plate replacement rod 11 is pushed upward, and its upper end abuts against the lower surface of needle plate 8, thereby exerting a force that pushes needle plate 8 upward.

At this time, if the lifting force of the needle plate replacement rod 11 acting on the needle plate 8 is offset by the elastic force of the needle plate springs 31 and 32, the needle plate 8 is released from the locked state formed by the locking claw 16 and the locking support 33, and therefore begins to rotate upward around the above-mentioned imaginary rotation axis at the front end of the fixing plates 21 and 22 held by the support plates 12 and 13, and the bent portions 31a and 32a of the needle plate springs 31 and 32 are disengaged from the embedded portions 14a and 15a of the engaging walls 14 and 15, and the engagement is released.

9( b ), the needle plate springs 31 and 32 completely separate from the engaging walls 14 and 15 , and the needle plate 8 is lifted upward to the removed position, returning to the state before installation.

Afterwards, even if the hand is removed from the needle plate replacement rod 10 and the needle plate replacement rod 11 is lowered to the non-operating position, as shown in Figure 7(a), the needle plate springs 31 and 32 return to their original shapes and are maintained in a state where their front end portions 31b and 32b reach the tapered portions 14b and 15b of the engaging vertical walls 14 and 15. Therefore, the needle plate 8 will return to the fixed position and will not adhere to the fixed surface of the base portion 4, and can be easily removed by hand.

Thus, in this embodiment, when the needle plate 8 is removed from the base portion 4, no additional tool is required, and the needle plate 8 can be removed by only a single-touch action of manually operating the needle plate replacement lever 10, and the disassembled state can be maintained even if the hand is removed from the needle plate replacement lever 10, so the disassembly operation can be easily performed.

As described above, the locked needle plate replacement device of this embodiment only requires the fixing pieces 21, 22 provided on one end side of the needle plate 8 to be inserted into the support plates 12, 13, and pressed down from above the side opposite to the end side where the fixing pieces 21, 22 are provided, so that the needle plate 8 can be positioned and installed, which can prevent the needle plate from unexpectedly rising and becoming a locked state. Moreover, since the locked state can be released and the needle plate 8 can be removed only by manually operating the needle plate replacement lever 10, the needle plate 8 can be extremely easily disassembled and assembled.

In addition, in this embodiment, the needle plate 8 is installed on the free arm portion 6 of the base portion 4, but it is needless to say that the present invention is not limited to this sewing machine with a free arm portion, and can be applied to sewing machines with base portions of various types.

In addition, the locking mechanism composed of the support plates 12, 13 and the fixing plates 21, 22 of this embodiment can guide and maintain the position of the needle plate 8 during installation and removal and perform effective operations, but this is not necessarily the case in the present invention, and the holding mechanism is not limited to the locking form of the needle plate springs 31, 32 and the embedded parts 14a, 15a of this embodiment. Various well-known locking forms can be used. The needle plate 8 can be fixed by simply pressing it down, and can be removed by simply lifting the needle plate 8.

Industrial applicability

The locking needle plate replacement device of the present invention can release the locking state and remove the installed needle plate with only a single action operation, and can position the needle plate and install it in a locked state through simple operation. Therefore, the needle plate can be efficiently replaced or the lower shaft movement mechanism can be maintained, etc., which is a device that is conducive to being widely used in various sewing machines.

Claims (7)

1. A locking needle plate changing device for attaching and detaching the needle plate from the base of a sewing machine, characterized in that it comprises: A positioning mechanism is provided on the base and the needle plate and is fitted together to position the needle plate at the installation position of the base. The locking mechanism has a locking component disposed on the base portion and a locked component disposed on the needle plate. By installing the needle plate at the mounting position of the base portion, the locking component and the locked component are locked together and the locked state is maintained. A lifting mechanism, located on the base portion, lifts the needle plate mounted on the base portion toward a disassembly position above the base portion; and The release mechanism, which is linked to the operation of the lifting mechanism, releases the locking mechanism from the locking state of the locking component and the locked component. The locking mechanism includes a hook-shaped locking pawl that is reciprocally movable on the base portion and a locking spring that applies force to the locking pawl in the locking direction. The locking mechanism includes a locking plate that hangs from the lower surface of the pin plate and engages with the locking claw portion. 2. The locking needle plate replacement device according to claim 1, characterized in that, The release mechanism includes a release component disposed on the lifting mechanism and an action component disposed on the locking claw portion that engages with the release component to cause the locking claw portion to move against the direction of the applied force. 3. The locking needle plate replacement device according to claim 1 or 2, characterized in that, The lifting mechanism includes: a needle plate changing lever, which is rotatably pivotally connected to the base portion; a needle plate changing bar, which, through the operation of the needle plate changing lever, pushes the lower part of the needle plate upward to lift the needle plate to a disassembly position above the base portion; and a return spring, which causes the needle plate changing bar to apply downward force. 4. The locking needle plate replacement device according to claim 1 or 2, characterized in that, It also includes a holding mechanism for holding the needle plate in the mounting position of the base portion. The retaining mechanism includes a needle plate spring with a curved portion disposed on the lower surface of the needle plate and an engaging wall disposed on the base portion, wherein the curved portion of the needle plate spring is embedded. 5. The locking needle plate replacement device according to claim 3, characterized in that, It also includes a holding mechanism for holding the needle plate in the mounting position of the base portion. The retaining mechanism includes a needle plate spring with a curved portion disposed on the lower surface of the needle plate and an engaging wall disposed on the base portion, wherein the curved portion of the needle plate spring is embedded. 6. The locking needle plate replacement device according to claim 4, characterized in that, The retaining mechanism also includes a locking component that locks the needle plate in the mounting position of the base portion. The locking component includes: a fixing piece disposed on the lower surface of the needle plate on the side opposite to the needle plate spring; and a support plate disposed on the base portion, which clamps the front end of the fixing piece between the support plate and the upper support wall of the base portion, and can rotate to hold the needle plate at a predetermined angle. 7. The locking needle plate replacement device according to claim 5, characterized in that, The retaining mechanism also includes a locking component that locks the needle plate in the mounting position of the base portion. The locking component includes: a fixing piece disposed on the lower surface of the needle plate on the side opposite to the needle plate spring; and a support plate disposed on the base portion, which clamps the front end of the fixing piece between the support plate and the upper support wall of the base portion, and can rotate to hold the needle plate at a predetermined angle.