CN1318189C

CN1318189C - Connecting lever

Info

Publication number: CN1318189C
Application number: CNB2003101141225A
Authority: CN
Inventors: 胡厚飞
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-11-20
Filing date: 2003-11-03
Publication date: 2007-05-30
Anticipated expiration: 2023-11-03
Also published as: CN1509845A

Abstract

The present invention provides a manual tool extension rod which comprises an extension rod, a clamping rod and a control element, wherein the extension rod is provided with a containing space opened at the lateral margin of the extension rod; a ball hole and a clamping hole are arranged at a preset position of the circumference of the extension rod in the longitudinal direction; the ball hole is communicated with the containing space and is used for accommodating steel balls; the clamping hole is communicated with a sealing end of the containing space; the clamping element can generate relative displacement with the containing space of the extension rod; the clamping element has a first end and a second end; the first end is provided with a sliding part and a supporting part; the second end is provided with a concave placing part; an elastic body is arranged between the control element and the extension rod; the control element can generate relative displacement with the clamping hole of the extension rod; the control element is provided with a sliding part and a supporting part. When the extension rod is in a locked state, the supporting part of the clamping element is abutted on the supporting part of the control element, so the clamping element can not generate the relative displacement with the containing space, and the steel balls arranged on the concave placing part can not downwards move.

Description

Extension bar

Technical field

The present invention relates to a kind of hand tools, refer to a kind of extension bar of hand tools especially.

Background technology

Since the human own civilization, hand-held tool just occupies the ground of a seat, and hand-held tool is day by day frequent especially, yet common articles for use in the daily life, furniture, or worker, employed machinery in the commerce, power tool, nearly all need use hand-held tool keeps in repair, hand-held tool just become the idea of work on the spot person indispensable partner, especially DIY in vogue after, in many consumer families, especially at multi-form, size and have the set of tools of different operating characteristics certainly, and the consumer is because of the raising of material level, to the requirement of things also from becoming quite fine and smooth with all right old thinking, have the product of continuous progress or innovation only, could satisfy the demand of modern society.

See also shown in the annex one, No. 2627789 locking types of Taiwan Announcement Number extension bar, it is equipped with the fastening position 21 of a hollow on a catch bar 20, and is arranged with a recess 22 and a groove 23 is ccontaining for steel ball in catch bar 20 front ends; One end that presses bar 30 is convexly equipped with a hook part 31, and hook part 31 and press bar 30 between form a sliding part 32, this presses bar 30 and is used for fastening to the fastening position 21 of catch bar 20, the extension bar of right this traditional type, when locking condition, when desiring to emerge in extension bar 10 if sleeve is subjected to external force, can move down by powerful compressing steel ball 15, and interlock catch bar 20 moves right, its catch bar 20 and press 30 on bar and do not have the top spacing structure of pulling, so do not have the function of locking, and recess 22 that its catch bar 20 front ends are arranged with and groove 23 are the designs of two stepwises, meaning is steel ball 15 only has two kinds of height in the hole of bead 14 variation, right because the fair value of the tolerance of the ditch hole in the sleeve when making is bigger, and the weight in each label ditch hole is all slightly different, can't be packed in the ditch hole so have the gap between the ditch hole of its steel ball 15 and sleeve, the extension bar of this traditional type does not have the function from dynamic(al) correction, rocks because of poor fit produces very significantly in being used between sleeve and extension bar.

See also shown in the annex two, the switch structure (one) of the 34946 No. three sleeve connecting rod of Announcement Number, it is arranged to the stepped of scalene cone in operating bar 30 front ends, use spring-go ejection positioning ball R and be revealed in hole outside person, and its operating bar 30 stage casings are opened to cut open and are made a caulking groove 33, and on connecting rod, give a farfetched interpretation and make slotted hole 16 corresponding to caulking groove 33 positions, for burying a shifting block 50 underground, and the prominent abaculus 51 of establishing in these shifting block 50 bottoms, just can be embedded in the caulking groove 33 of operating bar 30, on shifting block 50, be drilled with spring 53 and dowel 54 in addition, a sheathed control loop 60 in connecting rod 10 again, wherein the road makes a groove in the control loop 60, as the usefulness of closing with dowel 54 roped parties, in groove, be drilled with an open-work again, the diameter of this open-work is slightly less than dowel, the usefulness of involutory dowel during for dismounting, the connecting rod structural design of this traditional type is quite complicated, member is numerous, built-up time and produce cost and all greatly improve, the connecting rod of right this traditional type, when locking condition, if sleeve is subjected to external force and desires to emerge in extension bar 10, can move down by powerful compressing steel ball 15, and interlock operating bar 30 moves right, its operating bar 30 can move in slotted hole 16 by interlock shifting block 50, its operating bar 30,60 of shifting block 50 and control loops do not have the top spacing structure of pulling, so do not have the function of locking, and the staged scalene cone of its operating bar 30 front ends design, meaning is positioning ball R only has two kinds of height in the hole of bead 14 variation, yet, because the fair value of the tolerance of the ditch hole in the sleeve when making is bigger, and the weight in each label ditch hole is all slightly different, so the ditch hole of its positioning ball R and sleeve asks to have the gap and can't be packed in the ditch hole, the extension bar of this traditional type does not have the function from dynamic(al) correction, rocks because of poor fit produces very significantly in being used between sleeve and extension bar.

See also shown in the annex three, the switch structure (two) of the 34946 No. two sleeve connecting rod of Announcement Number, the technological means of the connecting rod structure of this traditional type generally is same as the structure shown in the above-mentioned annex two, the extension bar of right this traditional type, when locking condition, if sleeve is subjected to external force and desires to emerge in extension bar 10, can move down by powerful compressing steel ball 15, and interlock catch bar 20 moves right, its catch bar 20,60 of toggle 50 and connecting rod 10 and clasps do not have the top spacing structure of pulling, so do not have the function of locking, and the set stepped scalene cone of making of its operating bar 30 front ends, meaning is positioning ball R only has two kinds of height in the hole of bead 14 variation, it is right because the fair value of the tolerance of the ditch hole in the sleeve when making is bigger, and the weight in each label ditch hole is all slightly different, can't be packed in the ditch hole so have the gap between the ditch hole of its positioning ball R and sleeve, the extension bar of this traditional type does not have the function from dynamic(al) correction, rocks because of poor fit produces very significantly in being used between sleeve and extension bar.

See also shown in the annex four, the 496268 No. two patent case of United States Patent (USP), it utilizes control piece 14 several steel balls 23 of control of a tool two abutment faces to push against positioning ball 15, right because of and abutment face two stepwises of its control piece 14 design, so positioning ball 15 only has the variation of two kinds of height in the hole of bead, it is right because the fair value of the tolerance of the ditch hole in the sleeve when making is bigger, and the weight in each label ditch hole is all slightly different, can't be packed in the ditch hole so have the gap between the ditch hole of its steel ball 15 and sleeve, the extension bar of this traditional type does not have the function from dynamic(al) correction, rock because of poor fit produces very significantly in being used between sleeve and extension bar, and

invar pearl

15,23 all can produce tolerance slightly when making, so utilize

several steel balls

15,23 designs that push, the manufacturing tolerance of its product integral body is very difficult to grasp, and its requirement on machining accuracy for the ccontaining space 20 of steel ball 23 is high, if the height in this space 20 is slightly high, the utmost point can cause steel ball 23 to be offset up and down, it is online that meaning is that the center of steel ball 23 is not positioned at same transverse axis, also can cause the protruding dew difficulty of positioning ball 15.

See also shown in Figure 15, be application case number the 9022216 No. four patent case, be the previous invention of the applicant, its pre-position in control piece 30 peripheries is concaved with a limiting section 31, this limiting section 31 radial penetration is set in control piece 30, and the structural strength of having cut down control piece 30, this control piece 30 might thereby produce and destroys, and necessity of the improvement of being researched and developed is arranged in fact.

In view of this, the inventor is for solving this problem, be to be determined to be engaged in the many years of experience of instrument manufacturing, research and development with it, expect and to develop practical invention, finally well-designedly after repeatedly exploitation improvement go out extension bar of the present invention, it can overcome the shortcoming of above-mentioned traditional type goods fully, in fact is one to have the invention of industry applications.

Summary of the invention

Purpose of the present invention is that a kind of extension bar is provided, elastomer in its extension bar hole clipping can move on the butted control piece, and the sliding part of its sliding part interlock clamping piece of mat, make clamping piece in accommodation space to outer displacement, so the rectifying plane of clamping piece tool oblique cone degree can push against steel ball and can be packed in the shallow different sleeve of various ditch hole depths to outer displacement,, the present invention do not have the function of section from dynamic(al) correction in order to do being had.And when extension bar is in the state of locking, pull in the top supporting part of control piece in the top supporting part top of clamping piece, and can't be to intrinsic displacement in accommodation space, therefore, this steel ball can't leave rectifying plane, and in the ditch hole that is fastened in sleeve that still continues, make sleeve can't emerge in the sleeve part of extension bar, and the still firm extension bar that is incorporated into.

For reaching above-mentioned purpose, the technological means that the present invention adopts is as follows:

A kind of extension bar, this extension bar one end are axially arranged with one by the open accommodation space of extension bar lateral margin, and vertically be provided with in the pre-position of extension bar periphery one can be for steel ball the ccontaining and hole of bead and that be communicated in accommodation space be communicated in the hole clipping of accommodation space blind end; One clamping piece, it is arranged in the above-mentioned accommodation space, and can produce relative displacement relation with accommodation space, one control piece, it is arranged in the above-mentioned hole clipping, and is provided with an elastomer between control piece and extension bar, makes this control piece produce relative displacement relation with hole clipping; It is characterized in that,

Described clamping piece, have first end and second end, first end of this clamping piece is provided with one and pushes up the district of pulling, this top pull the district setting be not covered with in whole end face, pull to distinguish and be provided with a sliding part in this top, be provided with a top supporting part above a sliding part, second end of this clamping piece is provided with a recessed portion of putting, this recessed rectifying plane that is provided with a tool oblique cone degree in the portion away from the second end place of clamping piece of putting;

Described control piece, its periphery pre-position is concaved with a spacing zone, this spacing zone is provided with two first sliding part and second sliding parts that form class, interface between first sliding part and second sliding part is one to be formed with a step-like top supporting part, this step-like top supporting part not radial penetration in control piece, and this top supporting part not radial penetration in control piece;

Wherein, when extension bar was in locking condition, the top supporting part of this clamping piece was resisted against the top supporting part of control piece, made clamping piece to make that the steel ball that is positioned at the hole of bead can't be to bottom offset to intrinsic displacement in accommodation space.

By above-mentioned technical characterictic, extension bar of the present invention has more the effect of enhancement really than traditional structure, now its advantage is discussed below:

(1). extension bar of the present invention, elastomer in its hole clipping can move on the butted control piece, and the sliding part by its sliding part interlock clamping piece, make clamping piece in accommodation space to outer displacement, be packed in the ditch hole of sleeve to outer displacement so the rectifying plane of clamping piece tool oblique cone degree can push against steel ball.And because of the relation of the relative displacement between control piece and clamping piece has multiple variation, so steel ball can be subjected to rectifying plane pushing and pressing and with the protruding hole of bead that is exposed to of multiple different height, the present invention is had does not have the function of section from dynamic(al) correction, and can be packed in the shallow different sleeve of various ditch hole depths, the present invention is a kind of structural design of tool progressive.

(2). extension bar of the present invention, when it is in the state of locking, pull in the top supporting part of control piece in the top supporting part of clamping piece top.When desiring to deviate from the sleeve part of extension bar if sleeve is subjected to external force, because of clamping piece can't be to intrinsic displacement in accommodation space, so steel ball can't leave rectifying plane, and in the ditch hole that is fastened in sleeve that still continues, make sleeve can't emerge in the sleeve part of extension bar, and the still firm extension bar that is incorporated into, its integrated structure is quite firm and reliable, the present invention is a kind of structural design of tool industry applications.

Relevant the technology used in the present invention, means and effect thereof, describe in detail in conjunction with preferred embodiment and conjunction with figs. now as after.

Description of drawings

Fig. 1: be three-dimensional combination figure of the present invention;

Fig. 2: be three-dimensional exploded view of the present invention;

Fig. 3: be the A-A cutaway view of Fig. 1;

Fig. 4: be cutaway view of the present invention, table is pushed control piece moves down steel ball, with the installing sleeve;

Fig. 5: be cutaway view of the present invention, show in the urgent ditch hole that is fastened in sleeve of steel ball;

Fig. 6: be cutaway view of the present invention, show its action signal from dynamic(al) correction;

Fig. 7: be cutaway view of the present invention, the table sleeve can't be located away from extension bar;

Fig. 8: be cutaway view of the present invention, table is pushed control piece moves down steel ball, with pulling off sleeves;

Fig. 9: be cutaway view of the present invention, show the recessed portion of putting and form V-groove;

Figure 10: be the three-dimensional exploded view of second embodiment of the invention;

Figure 11: be the cutaway view of second embodiment of the invention;

Figure 12: be the cutaway view of second embodiment of the invention, table is pushed control piece moves down steel ball;

Figure 13: be the cutaway view of third embodiment of the invention;

Figure 14: be the cutaway view of fourth embodiment of the invention;

Figure 15: be the three-dimensional exploded view of the previous invention of applicant;

Annex one: be the patent gazette of Announcement Number the 26278 No. nine " locking type extension bar ";

Annex two: be Announcement Number the 34946 No. three " switch structure of sleeve connecting rod (one's) " patent gazette;

Annex three: be Announcement Number the 34946 No. two " switch structure of sleeve connecting rod (twos') " patent gazette;

Annex four: be the patent case of No. the 4962682, United States Patent (USP).

Symbol description among the figure

10........ extension bar 11....... sleeve part

12...... the accommodation space 13........ hole of bead

14........ hole clipping 15....... elastomer

The shape spring 16........ steel ball 18...... changes

19...... brute spring 20....... clamping piece

The district 22....... sliding part 21....... pull in the top

24....... the recessed portion of putting of top supporting part 26.......

27....... rectifying plane 29....... groove

30....... control piece 31....... spacing zone

32..... the first sliding part 33...., second sliding part

34....... top supporting part 36....... press section

40........ sleeve 41........ ditch hole

42........ wall

22 ' ... sliding part 24 ' ... top supporting part

33 ' ... sliding part 34 ' ... top supporting part

22 " ... sliding part 33 " ... sliding part

The specific embodiment

See also Fig. 1～Figure 14, be the concrete structure of the selected a kind of embodiment of the present invention shown in the figure, this only for the usefulness of explanation, is not subjected to the restriction of this kind structure in patent application.

The present invention mainly provides a kind of extension bar, please consults Fig. 1, shown in Figure 2 earlier, and it includes:

One extension bar 10, these extension bar 10 1 ends are provided with a sleeve part 11, this sleeve part 11 is generally rectangle and can supplies the usefulness of various instrument sockets such as sleeve, be axially arranged with one in this sleeve part 11 by the open accommodation space 12 of extension bar 10 lateral margins, and the pre-position on this sleeve part 11 vertically is provided with a hole of bead 13, this hole of bead 13 is communicated in accommodation space 12, and vertically is provided with a hole clipping 14 in the pre-position of extension bar 10 peripheries, and this hole clipping 14 is communicated in the blind end (as shown in Figure 2) of accommodation space 12;

One clamping piece 20, this clamping piece 20 is generally a body of rod, it has first end and second end, first end of this clamping piece 20 is provided with one and pushes up the district 21 of pulling, district's 21 the setting of pulling of this top is not covered with in whole end face, and the district 21 of pulling, this top is provided with a sliding part 22 in present embodiment, and the top of this sliding part 22 is provided with a top supporting part 24, second end of this clamping piece 20 is provided with a recessed portion 26 of putting, this recessed rectifying plane 27 that is provided with a tool oblique cone degree in the portion 26 away from the second end place of clamping piece 20 of putting;

One control piece 30, this control piece 30 is generally a body of rod, the periphery pre-position of this control piece 30 is concaved with a spacing zone 31, the setting of this spacing zone 31 not radial penetration in control piece 30, and can make control piece 30 obtain preferable structural strength, this spacing zone 31 is provided with two first sliding part 32 and second sliding parts 33 that form class in present embodiment, and is provided with a top supporting part 34 between this first sliding part 32 and second sliding part 33, and an end of this control piece 30 is provided with a press section 36;

See also Fig. 2, shown in Figure 3, a control piece 30 and an elastomer 15 can be inserted in the hole clipping 14 of extension bar 10, press section 36 protruding being exposed to outward of this control piece 30 can supply to push.And clamping piece 20 is packed in the accommodation space 12 of extension bar 10, and the district 21 of pulling, the top of this clamping piece 20 is engaged in the spacing zone 31 of control piece 30.See also Fig. 3, the sliding part 22 of this clamping piece 20 is close proximity to the sliding part 33 of control piece 30.A steel ball 16 is arranged in the hole of bead 13 of extension bar 10 and riveted in addition, this steel ball 16 is positioned at the rectifying plane 27 of clamping piece 20 again, and part is protruding is exposed to outside the hole of bead 13;

When desire is incorporated into the sleeve part 11 of extension bar 10 with sleeve 40 installings, see also shown in Figure 4, can apply the press section 36 of an external force in control piece 30, make control piece 30 compresses elastomeric 15, and produce relative length travel relation with the hole clipping 14 of extension bar 10, hold to go in the hole of bead 13 of extension bar 10 because the wall of sleeve 40 can push against the protruding outer steel ball 16 that is exposed to, can in accommodation space 12, contract by interlock clamping piece 20 when this steel ball 16 moves down.See also Fig. 4, when desire was incorporated into the sleeve part 11 of extension bar 10 with sleeve 40 installings, the sliding part 22 of this clamping piece 20 can slide along first sliding part 32 of control piece 30.At this moment, this steel ball 16 can hold the recessed of clamping piece 20 and puts in the portion 26;

When sleeve 40 is installed up to the location and desire when sleeve 40 is locked in the sleeve part 11 of extension bar 10, see also shown in Figure 5, when external force removes in control piece 30, this control piece 30 can be subjected to the butted of elastomer 15 and to top offset, this moment, first sliding part 32 of control piece 30 spacing zones 31 can push up the sliding part 22 in the district 21 of pulling by pushing and pressing clamping piece 20, force clamping piece 20 to accommodation space 12 outer displacements, originally be positioned at the recessed steel ball 16 of putting portion 26 and slide onto on the rectifying plane 27 and make, at this moment, steel ball 16 can produce relative displacement relation with the hole of bead 13 of extension bar 10 and on move protruding being exposed to outside the hole of bead 13, and be fastened in the ditch hole 41 of sleeve 40 internal faces 42, make the firm sleeve part that is incorporated into extension bar 10 11 of sleeve 40;

Because the fair value of the tolerance of the ditch hole 41 of sleeve 40 when making is bigger, and the weight in each label ditch hole 41 is neither identical.The control piece 30 of extension bar 10 of the present invention be subjected to elastomer 15 butted and on when moving, the sliding part 22 of first sliding part, the 32 meeting interlock clamping pieces 20 of this control piece 30, make clamping piece 20 in accommodation space to outer displacement, so the rectifying plane 27 of clamping piece 20 tool oblique cone degree can be packed in the different sleeve 40 of various ditches hole 41 depths to outer displacement by pushing and pressing steel balls 16.In other words, the manufacturing tolerance of the rectifying plane 27 automatically calibrating grooves 41 of this clamping piece 20 makes the sleeve part that is incorporated into extension bar 10 11 that sleeve 40 can be firm;

It should be noted that, be installed in the sleeve part 11 of extension bar 10 when ditch hole 41 more shallow sleeves 40, see also Fig. 6, the top supporting part 24 of this clamping piece 20 is resisted against the top supporting part 34 of control piece 30, and the sliding part 22 of clamping piece 20 is resisted against second sliding part 33 of control piece 30.Elastomers 15 in extension bar 10 hole clippings 14 can move on the butted control piece 30, and the sliding part 22 by its second sliding part, 33 interlock clamping pieces 20, make steel ball 16 reveal and be packed in the ditch hole 41 of sleeve 40 to evagination.This steel ball 16 can be packed in the groove 41 of sleeve 40, makes the sleeve part that is incorporated into extension bar 10 11 (shown in Fig. 6 solid line) that sleeve 40 can be firm;

Please continue to consult Fig. 6, be installed in the sleeve part 11 of extension bar 10 when ditch hole 41 darker sleeves 40, elastomer 15 in extension bar 10 hole clippings 14 can move on the butted control piece 30, and the sliding part 22 by its second sliding part, 33 interlock clamping pieces 20 makes steel ball 16 more reveal and be packed in the ditch hole 41 of sleeve 40 (shown in Fig. 6 dotted line) to evagination.The top supporting part 24 of this clamping piece 20 is not resisted against the top supporting part 34 of control piece 30, second sliding part 33 that is resisted against control piece 30 that the sliding part 22 of clamping piece 20 is then lasting.This steel ball 16 can be packed in the groove 41 of sleeve 40, makes the sleeve part that is incorporated into extension bar 10 11 that sleeve 40 can be firm.Therefore, this extension bar 10 can be used in the different sleeve 40 of various ditches hole 41 depths;

When the external force along the direction of arrow puts on sleeve 40, see also Fig. 7, the top supporting part 24 of this clamping piece 20 is resisted against the top supporting part 34 of control piece 30, and clamping piece 20 can't be to intrinsic displacement in accommodation space 12.Therefore, this steel ball 16 can't leave rectifying plane 27, and in the ditch hole 41 that is fastened in sleeve 40 that still continues, this sleeve 40 can't emerge in the sleeve part 11 of extension bar 10;

See also Fig. 8, show that sleeve 40 is located away from extension bar 10 normally.Push control piece 30 compresses elastomeric 15, this clamping piece 20 can be toward the direction displacement of control piece 30, and allows to contract in the steel ball 16, and sleeve 40 can be moved outside the direction of arrow;

This clamping piece 20 recessed puts portion 26 and rectifying plane 27 can be replaced, and sees also Fig. 9, and the suitable place of the periphery of this clamping piece 20 is provided with the groove 29 of a V-type.This V-groove 29 has the function from the manufacturing tolerance of dynamic(al) correction groove 41 too;

See also Figure 10 to shown in Figure 12, be the second embodiment of the present invention, and this embodiment is all similar to the above embodiments in many directions, so identical member adopts and previous identical element numbers; The main change of present embodiment be in the spacing zone 31 with control piece 30 change be made as single sliding part 33 ', and with the top of clamping piece 20 pull district's top supporting part 24 of 21 ' change be located at sliding part 22 ' the below.The effect that this second embodiment is reached is same as first embodiment;

See also shown in Figure 13ly, be the third embodiment of the present invention, the suitable place of an ora terminalis of this clamping piece 20 is provided with a sliding part 22 that is standing shape ", the effect that this 3rd embodiment is reached is same as first embodiment;

See also shown in Figure 14ly, be the fourth embodiment of the present invention, the suitable place of an ora terminalis of this control piece 30 is provided with an outstanding sliding part 33 ", the effect that this 4th embodiment is reached is same as first embodiment.

Though structural design of the present invention is quite simple and easy, but in limited field, technical development space, as small improvement is arranged technically, produce handy or practical effect, still be considered as " having certain effect of enhancement ", moreover with regard to the spirit of patent, it is constantly brought forth new ideas and to invent encouraging, and the present invention has quite excellent intention, and it has produced suitable effect in limited space, have its creativeness and novelty really.

In sum, the present invention has value on the industry; And not seeing again has identical or similar invention to come across domestic and international publication or public use, the real positive and passive important document that has met patent statute, special application patent of invention.

Only the above, only be preferred embodiment of the present invention, when can not with qualification scope of the invention process, so the displacement of the change of numerical value or equivalent elements such as, or, all should still belong to the category that patent of the present invention contains according to equalization variation and modification that the present patent application claim is done.

Claims

1. an extension bar (10), this extension bar one end is axially arranged with one by the open accommodation space (12) of extension bar lateral margin, and vertically be provided with in the pre-position of extension bar periphery one can be for steel ball the ccontaining and hole of bead (13) and that be communicated in accommodation space (12) be communicated in the hole clipping (14) of accommodation space (12) blind end; One clamping piece (20), it is arranged in the above-mentioned accommodation space (12), and can produce relative displacement relation with accommodation space (12), one control piece (30), it is arranged in the above-mentioned hole clipping (14), and between control piece (30) and extension bar (10), be provided with an elastomer (15), in order to do making this control piece (30) produce relative displacement relation with hole clipping (14); It is characterized in that this extension bar also includes:

Described clamping piece (20), have first end and second end, first end of this clamping piece (20) is provided with one and pushes up the district (21) of pulling, the pull setting in district (21) of this top is not covered with in whole end face, the district (21) of pulling, this top is provided with a sliding part (22), be provided with a top supporting part (24) in the top of a sliding part (22), second end of this clamping piece (20) is provided with a recessed portion (26) of putting, this recessed rectifying plane (27) that is provided with a tool oblique cone degree in the portion (26) away from the second end place of clamping piece (20) of putting;

Described control piece (30), its periphery pre-position is concaved with a spacing zone (31), this spacing zone (31) is provided with two first sliding part (32), second sliding parts (33) that form class, interface between first sliding part (32) and second sliding part (33) is one to form a step-like top supporting part (34), and this top supporting part (34) not radial penetration in control piece (30);

Wherein, when extension bar (10) when being in locking condition, the top supporting part (24) of this clamping piece (20) is resisted against the top supporting part (34) of control piece (30), makes clamping piece (20) to make that the steel ball (16) that is positioned at the hole of bead (13) can't be to bottom offset to intrinsic displacement in accommodation space (12).

2. extension bar as claimed in claim 1, wherein second sliding part of this control piece (30) (33 ") forms standing shape.

3. extension bar as claimed in claim 1, wherein the sliding part of this clamping piece (20) (22 ") forms standing shape.

4. extension bar as claimed in claim 1, wherein second sliding part (33) of this control piece (30), first sliding part (32) form the inclined-plane sliding part.

5. extension bar as claimed in claim 1, wherein the sliding part (22) of this clamping piece (20) forms the inclined-plane sliding part.

6. extension bar as claimed in claim 1, wherein the top supporting part (34) of this control piece (30) is located at the top of second sliding part (33) relatively.

7. extension bar as claimed in claim 1, wherein the top supporting part (34) of this control piece (30) is located at the below of first sliding part (32) relatively.