Patent Application
20140261122
1. Field of the Invention
The present invention relates to a sewing machine, and more particularly to a cutting device for a sewing machine.
2. Description of the Prior Art
The applicant's former invention called “cutting structure for a sewing machine” has been patented in Taiwan with the patent serial No. 90224753 and another invention called “sewing machine” has also been patented in USA with the patent No. 6892658. Both inventions are invented based on the working principle of the four-bar linkage mechanism to make the upper blade move stably, and allow the lower blade to be adjusted in position with respect to the needle plate.
However, the applicant of the present invention is not satisfied with the improvement made in the Taiwan Patent serial No. 90224753 and has made further improvement to the sewing machine of Patent No. 6892658.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.
The primary objective of the present invention is to provide a cutting device for a sewing machine, wherein the upper-blade drive member cooperates with the guide member which is fixed on the base to enhance the stability of movement of the upper blade. The lower-blade positioning device has an adjustment member which is pivoted to the base and screwed with the lower-blade holder, and the adjustment member is rotated by a rotary button. The relative angle between the rotary button and the adjustment member is also adjustable so as to further enhance the rotation-angle adjustment capability of the adjustment member.
To achieve the above objective, a cutting device for a sewing machine, the sewing machine includes a driven shaft and uses an upper-blade drive device to move an upper blade of an upper-blade positioning device mounted on a base of the cutting device, on the base is further disposed a lower-blade positioning device. The upper-blade drive device is linked to a first end of a connecting rod via the driven shaft and a driven member. The upper-blade positioning device includes the upper blade, an upper-blade holder, a spring, a restricting member and a restricting pin, the upper blade is fixed at a head portion of the upper-blade holder, and the spring and the restricting member are sleeved on a body portion of the upper-blade holder. The upper-blade positioning device further includes an upper-blade drive member, the upper-blade holder is inserted through the upper-blade drive member and the spring, and the restricting pin is engaged between the upper-blade drive member and the restricting member. A guide member is fixed to the base, and the upper-blade drive member has one end inserted through a guide member of the base and driven to move by the second end of the connecting rod, and the guide member includes a guide hole for insertion of a rod portion of the upper-blade drive member.
Another objective of the present invention is to provide a cutting device for a sewing machine, wherein the upper-blade positioning device is simplified, the upper-blade drive member is integrally designed and provided for mounting of relative parts of the upper-blade positioning device, so as to simplify the structure of the upper-blade positioning device while reducing relative manufacturing and assembling cost.
Another objective of the present invention is to provide a cutting device for a sewing machine, wherein the lower blade can be adjusted more efficiently. With the arrangement of the rotary button, the adjustment member, and the threaded engagement between the adjustment member and the lower-blade holder, the lower-blade holder can be adjusted more quickly and precisely.
The present invention will be clearer from the following description when viewed together with the accompanying drawings, which show, for purpose of illustrations only, the preferred embodiment in accordance with the present invention.
Referring to
The driven shaft 13 inside the base 11 is driven by a power source in the form of a motor and has one end linked to the upper-blade drive device 20 which includes a drive member 21 in the form of a cam, and an annular driven member 22 sleeved on the drive member 21. The upper-blade drive device 20 is fixed to the driven shaft 13 by a bolt inserted through the drive member 21. The driven member 22 has a lower end driven by a first end 241 of a connecting rod 24, and in the middle of the connecting rod 24 is disposed a pivot 23 with two ends pivoted to the base 11. A second end 242 of the connecting rod 24 is formed with an elongated slide groove 240, and a power transmission member 25 has a square end slidably disposed in the slide groove 240 and has a pivot portion 250 extending toward the upper-blade positioning device 30 of the cutting device A.
The upper-blade positioning device 30 includes the upper blade 31, an upper-blade holder 32, a spring 33, a restricting member 34 and a restricting pin 35. The upper blade 31 is formed at an end thereof with an elongated adjustment hole 310. The upper-blade holder 32 includes a head portion 320 in which being formed a positioning groove 321, and a body portion 322 whose diameter is smaller than the head portion 320. The upper blade 31 is fixed in the positioning groove 321 of the upper-blade holder 32 by an adjustment bolt 311 inserted through the adjustment hole 310 of the upper blade 31. The body portion 322 of the upper-blade holder 32 is inserted in the spring 33 and a central hole 340 of the annular restricting member 34, and the restricting pin 35 is locked on an outer periphery surface of the restricting member 34. The restricting pin 35 and the upper-blade holder 32 are simultaneously inserted in an upper-blade drive member 36 in such a manner that the spring 33 and the restricting member 34 are sleeved on the upper-blade holder 32. The upper-blade drive member 36 has one end inserted through a guide member 37 of the base 11 and pivoted to the pivot portion 250 of the power transmission member 25, so that motion of the connecting rod 24 can be transmitted to the upper-blade drive member 36 via the power transmission member 25, causing the upper-blade drive member 36 to move along the direction of the guide member 37, namely, the motion direction of the upper-blade drive member 36 is restricted by the guide member 37.
The guide member 37 includes an ear portion 370 in which being formed a first aperture 371 and a second aperture 372 which is located below the first aperture 371 and has a diameter larger than the first aperture 371. A fixing bolt 38 is inserted through the first aperture 371 to fix the guide member 37 to the base 11 in such a manner that the ear portion 370 flatly abuts against the surface of the base 11, and the inserting shaft 111 inserts through the second aperture 372. The ear portion 370 of the guide member 37 is further provided with a guide hole 373 which is square in cross section for insertion of the upper-blade drive member 36, and the guide hole 373 has a certain length, so that the upper-blade drive member 36 can be stably guided to move within the guide hole 373. The outer peripheral surface of the guide hole 373 is abutted against and engaged with the engaging portion 112 of the base 11, so as to fix the guide member 37.
Referring then to
The restricting member 34 is an annular structure formed on the outer periphery surface thereof with two opposite restricting grooves 341 which are semicircular in cross section, so that, when the restricting pin 35 is selectively engaged in one of the restricting grooves 341, the upper blade 31 can be moved and positioned at different positions by the upper-blade holder 32 which is linked to the restricting member 34. For example, as shown in
The lower-blade positioning device 40 includes a lower blade 41, a lower-blade holder 42, an adjustment member 43 screwed with the lower-blade holder 42, a rotary button 44 covers the adjustment member 43 and is exposed out of the lower-blade holder 42, and a lower-blade shaft 45 fixed to the base 11 and pivotally inserted in the adjustment member 43. As shown in
The adjustment member 43 is a hollow cylinder formed with an axial hole 430, and the lower-blade shaft 45 is inserted in the axial hole 430 and fixed therein by an E-shaped retainer clipped on the end of the lower-blade shaft 45 extending out of the base 11, so that the adjustment member 43 is pivotally mounted on the lower-blade shaft 45. The adjustment member 43 is formed on a shaft portion with a threaded adjustment portion 434, an outer diameter of the shaft portion of the adjustment member 43 is approximately equal to that of the threaded hole 424, and a head portion of the adjustment member 43 exposed out of the lower-blade holder 42 is formed with a plurality of passive teeth 431.
The rotary button 44 is formed with a cavity 441 and a stop piece 440 extending from a periphery of the cavity 441. The stop piece 440 is to be inserted in the guide groove 425 and stopped against the stop portion 426. The cavity 441 has an inner diameter approximately equal to an outer diameter of the adjustment member 43 and is formed with a plurality of active teeth 442 for meshing with the passive teeth 431, so that the rotary button 44 can rotate the adjustment member 43 to adjust the position of the lower-blade holder 42 with respect to the adjustment member 43. The stop piece 440 is further provided with a flexible locking portion 443. The rotary button 44 is sleeved onto the shaft portion of the adjustment member 43, and the locking portion 443 is engaged with the threaded adjustment portion 434. A slot 444 is formed around the locking portion 443 to make the locking portion 443 flexible.
The lower-blade shaft 45 has one end fixed to the base 11 and has another end extended out of the base 11 and formed with an annular groove 450 for holding of elastic ring 451 which has an outer diameter, so that the elastic ring 451 can partially protrudes out of the annular groove 450 to push against the adjustment member 43, making the adjustment member 43 and the lower-blade shaft 45 more stably assembled together, preventing undesired vibration from occurring between the adjustment member 43 and the lower-blade shaft 45.
When the active teeth 442 of the rotary button 44 are engaged with the passive teeth 431 of the adjustment member 43, the rotary button 44 can rotate the adjustment member 43 to adjust the position of the lower-blade holder 42. If the lower-blade holder 42 has not been adjusted to the desired position after adjustment, the user can pry the locking portion 443 away from the threaded adjustment portion 434 with a tool, and remove the rotary button 44 from the adjustment member 43, as shown in
To summarize, the present invention possess the following advantages:
1. transmission structure is simplified: with the guide member 37 guiding the motion of the upper-blade drive member 36, and with the connecting rod 24 of the upper-blade drive device 20 pivoted to the pivot 23, the transmission structure of the present invention can assuredly be simplified.
2. the upper-blade positioning device is simplified: the upper-blade drive member 36 is integrally designed and provided for mounting of relative parts of the upper-blade positioning device 30, which simplifies the structure of the upper-blade positioning device 30 while reducing relative manufacturing and assembling cost.
3. more efficient adjustment: with the arrangement of the rotary button 44, the adjustment member 43, and the threaded engagement between the adjustment member 43 and the lower-blade holder 42, the lower-blade holder 42 can be adjusted more quickly and precisely.
While we have shown and described various embodiments in accordance with the present invention, it is clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.
