GB2214854A

GB2214854A - Locking device for use with shears

Info

Publication number: GB2214854A
Application number: GB8813709A
Authority: GB
Inventors: Kimikazu Ishida; Tsuneo Ishida
Original assignee: Saboten Co Ltd
Current assignee: Saboten Co Ltd
Priority date: 1988-01-22
Filing date: 1988-06-09
Publication date: 1989-09-13
Also published as: KR900007506Y1; KR890015784U; JPH0440445Y2; JPH01112650U; GB8813709D0; DE3810222A1

Description

1.

p f h v 1 ', L -A 1 2 14 8.. 5.4 ' Lnnk i n er T)Pvit-p- fnr TT--p- jith R11P2rq The present invention relates to a locking device for use with a pair of shears or scissors having a spring to energize a pair of blades in the opening direction, i.e. spring biased in the open position, more particularly, to a pair of shears suited for use with h-orticulture having a looking device capable of retaining blades in the fully closed position.

Conventional shears made available for horticulture uses a spring to bias a pair of blades in the direction of opening themselves so that the unit can easily be handled. It is essential however that these shears be securely locked to prevent blades from opening themselves when not being used.

There are a variety of locking devices which are conventionally used for shears. For example, a looking device shown in FIG. 17 in which the engaging member B is axially installed on blade A of a pair of blades performing rotative sliding operation relative to each other, so that the engaging member B is engageable with and disengageable from part of the other blade D. Another looking device shown in FIG. 18 axially installs the engaging member B to either of handle E and F which are respectively connected to blades A and D to allow the engaging member B to be engaged with and disengaged from the other handle. Another looking device shown in FIG. 19 installs ring-like or hooked engaging member G to the base-end member F to allow the engaging member G to be engaged with and disengaged from handle E.

It is essential that any of those conventional locking devices for use with a pair of shears be engaged with or disengaged from the counterpart by perfoiming an operation independent of the gripping operation using the hand grasping the shears or the other hand. This results in the poor operative efficiency.

The present invention seeks to provide a novel looking device which automatically unlocks itself when the k 19 1 2 operator firmly grasps the hand of the shears in the fully closed position, thus offering useful shears featuring easier handling convenience.

According to the present invention there is provided a looking device for use with a pair of shears having an axially mounted pair of blades with a centre screw for causing said blades to be biased in the opening direction by applying a spring, comprising:

a looking member adapted to lock the blades in the closed position, which is provided for either a blade or its handle, said member being engaged with a weak spring and capable of freely moving itself to and from the other blade or the handle of said other blade; and said other blade or its handle is provided with a cutout portion, said cutout portion allowing the tip end of said looking member to freely move itself in the forward and backward directions when both of said blades remain fully closed; wherein part of said looking member is pressed against lateral surface of said cutout portion and firmly held inside of said cutout portion by resilient force of another spring which biases said blades in the,direction of opening themselves.

The invention will now be described by way of example with reference to the accompanying drawings, in which:

FIG. 1 _is the front view of a pair of shears incorporating the locking device related to the invention; FIG. 2 is the plan-of the shears shown in FIG. 1; FIG 3 is the exploded perspective view of the shears shown in FIGs. 1 and 2.

FIGs. 4 through 6 are respectively the simplified diagrams denoting operations of the handle and locking member of the locking device with partially bared portion, wherein FIG. 4 denotes the condition in which the handle unit is fully closed, FIG. 5 denotes the locked condition, FIG. 6 denotes the state of the shears ready for use after releasing the locked condition, t z 3 FIG. 7 denotes the front view of the lower handle; FIG. 8 is the sectional view of the lower handle shown in FIG 7 taken on line VIII through VIII; FIG. 9 is the front view of the upper handle; FIG. 10 is the sectional view of the upper handle; FIG. 11 is the front view of the looking device; FIG. 12 is the rear view of the locking device; FIG. 13 is the rear view of the looking device when the position of the locking member is shifted; FIG. 14 is the horizontal sectional view of the locking device; FIG. 15 is the vertical sectional view of the axially-mounted portion of the blade unit; FIG. 16 is the front view of the shears denoting another preferred embodiment having the varies configuration; and FIGs. 17 through 19 are respectively the front views of typical conventional looking devices.

The locking device embodied _by the invention is designed for use with a pair of shears and having a pair of blades 3 and 4 which are axially installed with centre screw 5 and spring 7 to energise, i.e. bias these blades 3 and 4 in the opening direction. The invention provides the blade 4 or its handle with looking member 22 which freely moves itself to and from the other blade 3 or its handle and is engaged in 24.

The opposite blade or its handle without having the looking member 22 is provided with cutout portion 33 which allows the tip end of the looking member 22 to freely move in the forward and backward directions when these blades are fully closed. This allows part of the locking member 22 to firmly be secured inside of the cutout portion 33 by being pressed against the lateral surface of the cutout portion 33 by the resilient force of spring 7 biasing blades 3 and 4 in the direction of opening themselves.

The preferred embodiment of the invention provides spring 24 drawing the locking member 22 backward with a the pull back direction by weak spring 4 where blade direction certain force weaker than that of the other spring 7 which biases blades 3 and 4 in the direction of opening themselves. The state of firmly holding the locking member 22 in position is materialised by friction resistance generated by pressure between the looking member 22 and the lateral surface of the cutout portion 33 due to resilient force of spring 7. Instead of this, the preferred embodiment of the invention may provide_part of the lateral surface of the-cutout portion 33 with a concave portion 34 to allow insertion of part of the locking member 22. Even when this constitution is introduced, the tip portion of the looking member 22 can move itself in the forward and backward directions when the blades 3 and 4 are fully closed.

The invention also provides a unit of shears which is substantially comprises of the blade unit 1 which axially mounts a pair of blades with a centre screw 5 and the handle unit 2 axially mounting a pair of handle members, unit 1 is secured to the tip portion of the handle unit 2 and an end of the connecting rod 20 is connected to blade 4 and the other end to part of the lower handle 11. When this constitution is introduced, the looking member 22 is set too the rotating pivot which axially mounts two handle members.

Referring now more particularly to the accompanying drawings, a preferred embodiment of the locking device of the invention is described below.

FIGS. 1 through 15 respectively denote preferred embodiments of the looking device related to the invention, in which the locking device is installed in shears mainly for use with lawn mowing where the locking device is comprises of a blade unit 1 and a handle unit 2. The tip end of the handle unit 2 provides a rotatable mount for the blades to allow the blades to vary the opening and closing angle from 00 to 900 against the vertical handle grasping The entire constitution of the shears incorporating the locking device related to the invention is expressly understood from FIGs 1 through 3.

z z The blade unit 1 axially mounts the lower blade 3 and the upper blade 4 with a centre screw 5 so that these blades can freely open and close themselves. To securely fix the upper blade 3. to the hand unit 2, a cylindrical member 6 is secured to the base edge of the blade 3. In order to secure a coiled spring 7 to the upper blade 4, a spring washer 8 is provided. The bottom edge of the centre screw 5 penetrates through blades 3 and 4 is secured to the lower blade 3.- The upper and lower ends of spring 7-are respectively engaged with the spring washer 8 which is secured to the blade 4 and an adjustment screw 9 set to the upper end of the centre screw 5 to allow the spring 7 to energise these blades 3 and 4 in the opening direction by applying resilient force, i.e. the blades are spring biased in the open position.

On the other hand, the handle unit 2 is substantially comprised of an upper handle 10 and a lower handle 11. Both of these handle members are axially connected together with a handle screw 12. A cylindrical washer 13 is provided on the front edge surface of the upper handle 10 for mounting the cylindrical member 6 of the handle unit 1. A throughhole 14 receiving part of the cylindrical member 6 is provided so that the blade unit 1 and the handle unit 2 can rotatably be installed. A volume nut 15 shown in FIG. 3 is set to the tip end of the cylindrical member 6 of the blade unit 1 extending through the through-hole 14 of the upper handle 10 so that the blade unit 1 can be prevented from coming out of the through- hole 14. A coiled spring 16 and a steel ball 17 respectively prevent the blade unit 1 from randomly rotating itself.

One end of a connecting rod 20 is connected to the bottom edge portion of the lower handle 11 by means of a metallic member 18 and a screw 19. The connecting rod 20 is connected to a connection hole 21 which is provided on the protruded side of the blade 4 through the rotating pivot of the blade unit 1 to allow the lower handle 11 and the blade 4 to jointly move themselves.

The handle unit 2 is provided with the locking device r 1 6 m which holds the handle in the fully closed position above the rotating pivot of the upper and lower handles 10 and 11. The looking device is substantially comprised of a looking member 22 which slides itself in the forward, i.e. towards the blade unit and backward directions, a cap 23 storing the looking member 22, and a weak spring 24 biasing the locking member 22 in the pullback direction.

As shown in FIGs. 11 through 14, the cap member 23 having a windof4 hole 25, stores the locking member 22, which slides itself in the horizontal direction along a guide slit 26 to allow the locking member 22 to project and retrea:t by a predetermined length via the operator's finger outside of the cap 23. The spring 24 is provide between the locking member 22 and the cap 23 for biasing the locking member 22 in the direction of retreating itself inside of the cap 23. The rear surface of the cap 23 is provided with a plurality of projections 27 for mounting the cap 23.

As shown in FIGs. 3,7 and 8, the axially mounted portion of the metallic lower handle 11 is provided with a plastic boss 28, while the surface of the boss 28 is provided with a plurality of holes 29 allowing insertion of the projected legs 271 of the cap 23, thus allowing the looking member 22 to be installed to the lower handle 11.

A through-hole 30 in the lower handle 11 allows connection of the connecting rod 20. A through-hole 31 in the lower handle 11 and another through-hole 32 in the upper handle 32 allows insertion of the handle screw 12.

As shown in FIGs. 9 and 10, the metallic upper handle 10 axially mounting the lower handle 11 is integrally molded with plastic material into an easily-grasping configuration. A cutout portion 33 is - provided in a specific portion exactly matching the position where the tip end of the locking member 22 projects and retreats itself in front of the throughhole 32 of the looking member 22 set to the lower handle 11 when blades 3 and 4 are fully closed by the firmly-grasped handle unit 2. In the accompanying drawings, the cutout portion 33 is shown as a blind hole which smoothly receives the inserted R Z t w, 7 locking member 22 and maintains the least clearance between its lateral surfaces and the top/bottom surfaces of the locking member 22.

As shown in FIG. 4, when the operator intensely grasps the upper and lower handle members together while the lower handle 11 is at the handling position I, the looking member 22 can freely enter into and go out of the cutout portion 33. Thus, when the operator manually pushes the looking member 22 forward through window hole 25 of the cap 23 and reduces the handle-grasping strength, the locking member 22 slightly rotates itself as shown in FIG. 5 to cause the upper tip portion to come into contact with the lateral surface of the cutout portion 33 before eventually securing the locking member 22 in position. -This in turn allows the lower handle 11 to remain locked at the handling position II.

When the operator uses the shears, first, he firmly grasps the upper and lower handles which are locked together as shown in FIG. 5. This causes the locking member 22 to be disengaged from the lateral surface of the cutout portion 33, while the locking member 22 is instantaneously drawn back by the effect of the spring 24. As a result, the lower handle can freely move itself between the handle position I shown in FIG. 4 and the handle position III shown in FIG. 6.

In order to securely hold the looking member 22 as shown in FIG. 5, friction resistance between the looking member 22 and the lateral surface of the cutout portion 33 generated by the rotating force of the locking member 22 via-spring 7 should be greater than the force generated by spring 25 which directly operates the locking member 22. However,-since the rotating force of the locking member 22 is inversely proportionLl to the distance from the rotating pivot, installation of the locking member 22 on the rotating axis condition- to securely be maintained. By minimizing clearance between the locking member 22 and the lateral surface of the cutout portion 33, idling distance between the handling positions I and II of the lower handle 8 11 is also minimised.

In operation, when blades 3 and 4 i.e, when the operator firmly grasps resisting the resilient force of spring 7 to the handle position I denoted by the shown in FIG. 1), the tip portion of the freelv moves into and freelv leaves the are fully closed, the handle unit (this corresponds two-dot chain line locking member 2 cutout portion 33 as shown in FIG. 4. When the operator releases his strength grasping the handle unit in the condition in which the tip portion of the locking member 22 is fully inserted in the cutout portion 33, the width of the blades slightly extends by resilient force of spring 7 up to the handle position II denoted by solid line shown in FIG. 1. This deviates the positions of the locking member 22 and the cutout portion 33 from each other. In other words, part of the locking member 22 is pressed against the lateral surface of the cutout portion 33 by resilient force of spring 24 before firmly being held to eventually achieve the locked condition as shown in FIG. 5.

When operating the shears in the unlocked condition, the operator firmly grasps the handle u it. While the operator firmly grasps the handle, as soon as the lower handle 11 reaches the handle position II shown in Fig. 1, the locking member 22 is pulled backward by resilient force of spring 24 to disengage the looking member 22 from the secured condition. This in turn allows the lower handle 11 to freely move itself between the handle positions I and III shown in FIG. 1 so that the blades 3 and 4 can freely be opened and closed as required. See FIG. 6.

FIG. I denotes a preferred embodiment of the locking device related to the invention when it is applied to a pair of shears comprised of the blade unit and the handle unit. Those functional operations described above can also be materialized by the preferred embodiment shown in FIG. 6.

When providing the lateral surface of the cutout portion 33 with concave 34 allowing insertion of part of the locking member 22, the concave 34 either causes the Y R, 1 9 friction force to increase against the locking member 22 or receives the force pulling the looking member 22 backward.

FIG. 16 denotes another preferred embodiment of the locking device related to the invention. Handles 10' and 11' are respectively and integrally secured to blades 3' and 4' for constituting a pair of shears. These blades 3' and 4' are axially connected to each other with centre screw 5'. Spring 7' biases these-blades in the direction of opening themselves. This preferred embodiment installs the looking member 22 having the constitution identical to that of the preceding preferred embodiment to the front edge of the handle 1V, where the tip portion of the locking member 22 can freely enter into and go out of the cutout portion 33' provided for the blade V. A concave portion 34 is provided inside of the cutout portion 33' to allow the billshaped tip of the locking member 22 to fully be inserted into the concave portion 34. Although depending on the configuration, the concave portion 34 causes the friction resistance to increase between the of the cutout looking member 22 and the lateral surface portion 331, or it receives the force from spring 24 to pull the locking member 22 backward.

The locking device embodies by the invention is installed to a position where thumb of the operator's hand grasping the handle can correctly push the looking member forward for locking the blades of shears, and thus, looking operation can be completed by merely loosening the strength grasping the handle.

The locking device related to the invention for.use with a pair of shears releases the locked condition by merely grasping the handle, and thus, the in vention offers useful shears featuring extremely easy handling operation.

This not only simplifies the locking and unlocking operations of the looking device during normal use, but it also provides much convenience for locking or unlocking the locking device when both cannot freely be used or while the other hand follows up execution of another work.

If the locking device related to the invention were 1 installed to the rotating pivotal portion of the handle, the force maintaining the locked condition generated by spring biasing a pair of blades in the direction of opening themselves can influentially be used. A concave portion provided inside of the cutout portion promotes the force for securely holding the locking member inside of the cutout portion. All of these constituents effectively prevent the locked condition from randomly be released, and at the same -time, these allow spring having substantial elasticity to be set to the looking member for securely releasing the locked condition.

The term shears is to be understood as including all implements having two mutually co-operating blades for providing a cutting action, for example, scissors amd the like.

R1 t J 11

Claims

CLAIMS:

1. A locking device for use with a pair of shears having an axially mounted pair of blades with a centre screw for causing said blades to be biased in the opening direction by applying-a spring, comprising:

a locking member adapted to lock the blades in the closed position, which is provided for either a blade or its handle, said member being engaged with a weak spring and capable of freely moving itself to and from the other blade or the handle of said other blade; and said other blade or its handle is provided with a cutout portion, said cutout portion allowing the tip end of said locking member to freely move itself in the forward and backward directions when both of said blades remain fully closed; wherein part of said locking member is pressed against lateral surface of said cutout portion and firmly held inside of said cutout portion by resilient force of another spring which biases said blades in the direction of opening themselves.

2. A locking device for use with a pair of shears as claimed in claim 1, wherein said shears are.substantially comprised of a blade unit having a pair of blades which are axially secured with centre screw, and handle unit having two handle members including the upper handle and the lower handle; wherein said shears are further comprised of mechanical constituents in which base-end member of said blade unit is rotatably mounted to the tip end of said handle unit, an end of connecting rod extending through the rotating pivot of said blade unit is connected to said blade and the other end of said connecting rod to an endhole of said lower secured to the handle members.

handle, and said locking member is rotating pivot which axially mounts two

3. A locking device for use with a pair of shears as 1 12 claimed in claim 1 or claim 2, wherein means for holding said locking member inside of said cutout portion is achieved by friction resistance caused by pressure between said looking member and lateral surface of said cutout portion generated by the energising force of spring.

4. A locking device for use with a pair of shears as claimed in claim 1 or claim 2, wherein a concavity is _provided on the lateral surface of said cutout portion for allowing insertion of part of said locking member.

0

5. A locking device as hereinbefore described with reference to and as illustrated in the accompanying figures 1 to 16.

Published 1989 atThe Patent Office, State House, 66171 High HolbornLo ndonWCIR 4TP- Further copies maybe obtainedfrom The Patent Office.

Sales Branch, St Mary Cray, Orpington, Kent BR5 3RD. Printed by Multiplex techniques ltd, St Mary Cray, Kent, Con. 1/87 1