CN102069478B - Electric hammer - Google Patents

Abstract

The invention relates to an electric hammer which comprises a shell, a motor, a transmission mechanism, an impacting assembly, a striking piece and a clamping mechanism, wherein the motor is vertically arranged in the shell; the transmission mechanism is used for converting rotary motions of the motor into impacting motions to the striking piece through bevel gear transmission and the impacting assembly; the impacting assembly comprises an impacting block in contact with an impacted part of the striking piece; the clamping mechanism comprises a sleeve, clamping pieces and an offsetting device; and the sleeve is used for driving the clamping piece to move between an opening position and a closing position. The electric hammer also comprises a holding part and a striking device formed by forwards protruding, wherein the striking device comprises a striking piece capable of linearly striking on a nail or other elements back and forth; and the striking device also comprises a clamping mechanism used for clamping the nail and other elements. The electric hammer has the advantages of compact structure and convenient operation and can be used for better clamping nails or other elements so as to prevent the nails or other elements from being deflected.

Description

Electric hammer

The application is that application number is 200910234451.0, the applying date is on November 19th, 2009, title is divided an application for " a kind of power hammer " China's application.

Technical field

The present invention relates to a kind of electric hammer, relate to especially a kind of electric hammer with clamp mechanism.

Background technology

In decoration, finishing field, electric hammer is a kind of instrument comparatively commonly used, number is 200820161342.1 electric hammers that disclose such as Chinese patent application, and it comprises the rifle mouth portion that a fuselage sections and links to each other with fuselage.The rifle mouth portion generally is made of the cylinder-shaped sleeve of a hollow, is drilled with the hole that can place magnet on this sleeve pipe, thereby magnet is engaged on and adsorbs the nail that is placed in the beating unit in this hole, thereby nail is clamped.The defective of its existence is: magnet is in sleeve edge, can't make nail be in cover tube hub and element not parallel with the sleeve pipe center line (being to be askew after nail adsorbs), and can not clamp other nonmagnetic material, such as dowel etc.

Summary of the invention

The object of the invention is to: the shortcoming for above-mentioned prior art exists, a kind of electric hammer is proposed, nail or other element can by firm being clamped in the beating unit, use thereby be convenient to the user.To achieve these goals, provide a kind of easy and simple to handle, visual good, the electric hammer of compact conformation, it comprises housing, motor, transmission mechanism, impact assembly, hit piece and clamp mechanism, this motor vertically is installed in the housing, transmission mechanism is by bevel gear and impact the percussion action that assembly converts rotatablely moving of motor to hit piece, this impact assembly comprise with hit piece divided the impact block that contacts by impact portion, this clamp mechanism comprises sleeve pipe, at least two clamping elements and bias unit, this sleeve pipe drives clamping element and moves between the open and close position, and this sleeve pipe is provided with groove, and clamping element slides in groove, the primary importance of clamping element opposed slot, clamping element is closed, the second place of clamping element opposed slot, and clamping element is opened.On a kind of like this electric hammer because hit piece can impact with very large power nail or other element, so the clamp mechanism that arranges therein can well clamping nail or other element, in order to avoid nail or other element are deflected.

Further, this bias unit comprises the first bias unit and the second bias unit, this first bias unit is used for impacting towards hit piece the direction off-set sleeve of element, also comprise a cutting ferrule in the electric hammer, thereby the second bias unit is used for impacting the directive effect of element in cutting ferrule off-set sleeve and these clamping elements towards hit piece.The benefit that is provided with the first bias unit and the second bias unit is that nail or other element can be by firm being clamped in the clamp mechanism.During work, nail or other element are clamped in the clamp mechanism, when being driven into the certain depth rear sleeve, nail contacts with workpiece, at this moment in order to continue nail is squeezed in the workpiece, then the user need to overcome the bias force of the first bias unit, so that sleeve pipe impacts the opposite direction motion of element to hit piece; When sleeve movement is the main body of clamp mechanism when contacting with workpiece to flushing with the main body of clamp mechanism, the user then need overcome the bias force of the first bias unit and the second bias unit, so that sleeve pipe continues to impact to hit piece the opposite direction motion of element.

Be provided with the groove group at least two faces of this sleeve pipe, the groove on each face is mutually symmetrical, and this clamping element comprises drive part, and this drive part places in the groove, and this drive part can move along groove.Preferably, be provided with the groove group on four faces of this sleeve pipe, the groove on each face is mutually symmetrical, and the drive part of clamping element places in the groove, and this drive part can move along groove.Four faces at sleeve pipe are provided with the groove group, so that the shank of the clamping nail that clamping element can be wider, the clamping better effects if.

Further, groove is set to broken line type, is conducive to like this sliding stroke of reentrant bushing, so that the more compact structure of complete machine.

Further, drive part is removably mounted on the clamping element and/or with clamping element all-in-one-piece is set.

Further, clamping element comprises each or any combination of claw, spring, magnet, screw or chuck for holding element.

Further, clamping element comprises groove, and in closing position, element is maintained in this groove, and at open position, element and this groove break away from.

Further, beating unit comprises a hit piece, when clamping element is positioned at open position, forms a release areas, and this hit piece can pass through this release areas.

Further, this clamp mechanism comprises a lining, and this lining can pass through this release areas.This lining is arranged on the periphery of hit piece, can effectively prevent like this nail or other element be stuck in machine especially clamping element open in the slit of generation.

Further, this bias unit comprises the 3rd bias unit, and the 3rd bias unit impacts the direction offset liner of element towards hit piece.

Further, clamping element can be interlocked, and is conducive to like this clamping element and opens simultaneously with closed simultaneously.

Further, sleeve pipe comprises a locking mechanism, and this locking mechanism comprises at least one projection and spanner, and after a projection and spanner locking, clamping element is positioned at open position, and after another projection and spanner locked, lining exposed from sleeve pipe.

Further, this sleeve pipe is provided with sheath.Thereby a toggle engages so that toggle moves with sheath with this sheath.The user can push sheath or promote toggle so that clamping element is opened.

Further, sheath and/or sleeve pipe are made by transparent material, make things convenient for the user to see the particular location of hit piece.

Further, thus sheath and/or sleeve pipe are provided with the visuality that groove increases element.

This electric hammer can be firm nail or other element are clamped, and small and exquisite, the user is easy to use, chucking power is reliable, can bail, visual good.

Description of drawings

The below is with preferred embodiment and the present invention is further illustrated by reference to the accompanying drawings.Wherein:

Fig. 1 is the schematic perspective view of electric hammer among the present invention.

Fig. 2 is the cutaway view that electric hammer shown in Figure 1 is done along the parting surface of two halves housing.

Fig. 3 is that electric hammer shown in Figure 1 is along the cutaway view of doing perpendicular to the direction of two halves housing parting surface.

Fig. 4 is the part explosive view of electric hammer transmission mechanism among Fig. 1.

Fig. 5 is the cutaway view that electric hammer shown in Figure 2 is done along the A-A axis.

Fig. 6 is the partial enlarged drawing of the clamp mechanism of electric hammer shown in Figure 1, and wherein, clamping element is positioned at closing position.

Fig. 7 is the partial enlarged drawing of the clamp mechanism of electric hammer shown in Figure 1, and wherein, clamping element is positioned at the fully open position.

Fig. 8 is that clamp mechanism shown in Figure 6 is along the cutaway view of B-B axis.

Fig. 9 is that clamp mechanism shown in Figure 7 is along the cutaway view of C-C axis.

Figure 10 is the schematic diagram that nail is clamped in the clamp mechanism and the sleeve pipe of electric hammer just contacts with workpiece, and at this moment, clamping element is positioned at soon open position.

Figure 11 be nail be tufted in the workpiece and the sleeve pipe of electric hammer on projection just back down the schematic diagram of spanner.

Figure 12 is the schematic diagram that nail is tufted in the workpiece and the main body of the clamp mechanism of electric hammer just contacts with workpiece, and at this moment, clamping element is positioned at the fully open position.

Figure 13 is the schematic diagram that nail is tufted in the workpiece and the lining of the clamp mechanism of electric hammer just contacts with workpiece.

Figure 14 is that nail is hammered into the schematic diagram in the workpiece fully.

The specific embodiment

As depicted in figs. 1 and 2, the electric hammer 1 of present embodiment comprises and holds motor M at interior housing 2 and beating unit 6, and housing 2 is by left and right sides two halves housing 2 ', 2 " involute.The main part of housing 2 forms substantially vertical holding area 4, and the upper end comprises head assembly 3, and this head assembly comprises transmission mechanism and protrudes forward the beating unit 6 that forms.

In the present embodiment, electric hammer 1 comprises a power brick (not shown), is used for powering to motor M.But disclosed electric hammer power supply mode is not limited to this, also can use AC-powered.Switch 7 is installed on the housing 2, is used for the start and stop of control motor M.Beating unit 6 comprises a hit piece 61, and these hit piece 61 basic horizontal in beating unit 6, and can be done straight reciprocating motion by spring fitting therein.During operation, hit piece 61 impact the end-acted on the objects such as the securing member such as member such as nail, dowel or fragment of brick of end 611.Also comprise a cavity volume 63 in the beating unit 6, it has the internal diameter greater than general nail or other element diameter, so the nail of various sizes or other element all can be put in the cavity volume 63.

As shown in Figure 3 and Figure 4, housing 2 contains rotation-rectilinear motion transmission mechanism, and this mechanism can be converted to rotatablely moving of motor M the ballistic motion of hit piece 61.Motor M vertically is installed in the housing 2, and motor shaft X ' up passes to rotary power on the rotating shaft 35 that is supported on housing top by bearings at both ends by comprising the stage-geared of bevel gear.Have a pair of skewed slot 36 on the rotating shaft 35,36 one-tenth openings of each skewed slot " V " font backwards.One impact block 31 is enclosed within on the rotating shaft 35, and this impact block 31 is roughly the cylinder of a hollow, and its inner cylinder face is provided with a pair of circular arc guide groove 37 relative with two skewed slots, 36 positions difference, and the circular arc opening direction of each guide groove 37 is opposite with " V " shape skewed slot 36.Skewed slot 36 and guide groove 37 are at the bottom of the semi arch.A pair of steel ball 38 lays respectively in the cavity volume that forms between corresponding skewed slot 36 and the guide groove 37, can relatively move along skewed slot 36 and guide groove 37.So can drive impact block 31 by the steel ball 38 that is positioned at skewed slot 36 when rotating shaft 35 rotates rotates.The a pair of projection 32 that is oppositely arranged along diametric(al) is arranged on the excircle of impact block 31.After operating switch 7, motor M starts, and by stage-geared, driven rotary axle 35 rotates, and rotating shaft 35 drives impact block 31 by steel ball 38 again and rotates together thereupon.

As shown in Figure 4, one energy-storaging spring 40 is loaded between impact block 31 and the rotating shaft 35, the one end withstands on the step 351 of rotating shaft 35, and the other end withstands on the impact block 31, and the axial force of this energy-storaging spring 40 is so that impact block 31 is in the first axial location of relative rotation axi 35.In this first axial positions, impact block 31 is done circular-rotation under the effect of rotating shaft 35 and steel ball 38, when impact block 31 turns to a certain position so that projection 32 can touch hit piece 61 time, because hit piece 61 is subject to the larger resistance that temporarily can't overcome this moment, the hit piece 61 temporary transient impact blocks 31 that stop rotate, force impact block 31 to be displaced to second axial location by the first axial location energy-storaging spring 40 that gradually reduces, at this second place place, the projection 32 of impact block 31 has been crossed hit piece 61, and braking is eliminated.Energy-storaging spring 40 begins to discharge its elastic potential energy, and the bounce of energy-storaging spring 40 not only makes impact block 31 axially reset towards primary importance, and passes through the acting in conjunction of skewed slot 36, guide groove 37 and steel ball 38, produces the High Rotation Speed that surmounts rotating shaft 35.As a result, the quilt of the projection 32 bump hit pieces 61 on the impact block 31 impacts end 612, and hit piece 61 forms one-shot with high-effect moving linearly.After impact is finished for the first time, when impact block 31 turns to again by hit piece 61 braking, enter for the second time impulse period, and the impact process after finishing in an identical manner.

To Fig. 9, also comprise a clamp mechanism 5 referring to Fig. 2, Fig. 5 in beating unit 6, it is used for clamping nail or other element.This clamp mechanism 5 is installed in the main body 51 of this clamp mechanism 5 for the form of clamping element 52a, 52b, 52c and 52d and its, clamping element 52a, 52b, 52c and 52d have primary importance, it is the clamping element closing position, such as Fig. 6 and shown in Figure 8, clamping element 52a and 52b are closed each other, clamping element 52c and 52d are closed each other, form a clamping region, and nail or other element can be maintained at this zone.Clamping element 52a, 52b, 52c and 52d have the second place, it is the clamping element fully open position, such as Fig. 7 and shown in Figure 9, clamping element 52a and 52b open each other fully, clamping element 52c and 52d open each other fully, form a release areas, hit piece can continue to impact nail by this release areas, until nail is hammered into workpiece fully.When clamping element was shown in an open position, nail or other element can be placed in the cavity volume 63, and then that clamping element is closed, nail or other element then are maintained at clamping region.Be provided with groove on each clamping element, so that these grooves just can be meshed with the arc of nail shank, increase the contact area of the shank of clamping element and nail or other element, clamp better effects if.And because clamping element can be conditioned, the nail of different size or other element can clamped independently maintenances.And clamping element is opened, and nail or other element just break away from groove.

Certainly those skilled in the art can expect easily that also above-mentioned clamping element can be each or any combination of claw, spring, magnet, screw or chuck for holding element.

Shown in Fig. 6-9, sleeve pipe 8 is arranged to the cuboid of hollow, is provided with the skewed slot group on the sleeve pipe 8, and four faces are respectively arranged with two skewed slots that are mutually symmetrical 81 and 82 up and down before and after it, the skewed slot of sleeve pipe front only is shown among Fig. 6, and the skewed slot of three faces is identical with the skewed slot of this face in addition.Skewed slot 81 and 82 also can arrange all-in-one-piece, thereby forms " V " type groove.And skewed slot 81 and 82 is not linear skewed slot, but the skewed slot of broken line type, helps like this stroke of reentrant bushing 8, so that the more compact structure of complete machine.Here said broken line type skewed slot refers to nonlinear groove, comprises arc groove, groove that the straight line of two or more pieces Different Slope forms etc. is arranged.The two ends that the drive part 53a of two clamping elements and 53b pass respectively clamping element 52a and 52b and each drive part are installed in respectively in the corresponding skewed slot 81,82 of sleeve pipe 8 upper and lower surfaces, and in addition two drive part 53c and the 53d two ends of passing respectively clamping element 52c and 52d and each drive part are installed in respectively in the corresponding skewed slot 81,82 of sleeve pipe 8 former and later two faces.Four drive parts form interlock, when clamping element is in primary importance, when being closing position, four clamping elements clamp nail, the two ends of drive part 53a lay respectively at an end of the corresponding skewed slot 81 of sleeve pipe 8 upper and lower surfaces, the two ends of drive part 53b lay respectively at an end of the corresponding skewed slot 82 of sleeve pipe 8 upper and lower surfaces, the two ends of drive part 53c lay respectively at an end of the corresponding skewed slot 81 on two sides, sleeve pipe 8 front and back, and the two ends of drive part 53d lay respectively at an end of the corresponding skewed slot 82 on two sides, sleeve pipe 8 front and back.Four drive parts skewed slot relatively separately moves together; Such as Fig. 7 and shown in Figure 9, when clamping element is in the second place, when being the fully open position, four clamping elements are opened each other, the two ends of drive part 53a lay respectively at the other end of the corresponding skewed slot 81a of sleeve pipe 8 upper and lower surfaces, the two ends of other drive part also lay respectively at the other end of skewed slot of two faces of each self-corresponding sleeve pipe, and hit piece 61 can therefrom pass and continue to impact nail, until nail is hammered in the workpiece fully.Be understandable that drive part also can be arranged to the structure that is integrated with clamping element.

During assembling, first each clamping element is placed in the main body 51 of clamp mechanism, then respectively each drive part is passed clamping element separately, at the outer surface of sleeve pipe 8 sheath 9 is installed again, this sheath 9 can prevent drive part disengaging sleeve pipe 8 and drop out from electric hammer.Main body 51 is connected to an end of cutting ferrule 10, and this main body 51 is with cutting ferrule 10 motions.Be understandable that drive part and clamping element also can arrange the all-in-one-piece structure.

Shown in Figure 10-14, the first bias unit provides with the form of spring 11, be used for sleeve pipe 8 is namely impacted towards hit piece the direction biasing of element left, thereby so that clamping element is positioned at closing position, one end of this spring 11 is contained on the sleeve pipe 8, and the other end is contained on the projection of cutting ferrule 10, when sleeve pipe 8 contacts with workpiece, the user need to overcome the pressure of the first bias unit, so that clamping element is opened.The second bias unit provides with the form of spring 12, be used for cutting ferrule 10 is namely impacted towards hit piece the direction biasing of element left, one end of this spring 12 is installed on the cutting ferrule 10, the other end is installed on the stop collar 13, when the end face 51a of main body 51 contacted with workpiece, this main body 51 overcame the pressure of the second bias unit with sleeve pipe 8 and moves.The 3rd bias unit provides with the form of spring 14, be used for lining 15 is setovered towards the direction that hit piece impacts element, one end of this spring 14 is installed on the gear-box, the other end is installed on the lining 15, when lining 15 contacts with workpiece, this lining 15 overcomes the pressure of the 3rd bias unit together with sleeve pipe 8 and cutting ferrule 10 and moves, until nail is hammered in the workpiece fully.

Above-mentioned spring can be Compress Spring or helical spring, and certainly those skilled in the art also can expect replacing with other elasticity or bias unit with attraction, repulsive force easily, for example can replace spring 11,12 and 14 with magnetic part.

In use, if clamping element is in the close position, as shown in Figure 2, then the user can promote sleeve pipe 8 by the pressure that toggle 21 overcomes the first bias unit 11 and moves right, this toggle 21 is installed on the housing 2, it engages with sheath 9, the user pulls toggle 21 drive sleeve pipes 8 to the right and sheath 9 moves right together, perhaps directly pressing sleeve pipe 8 moves right, when hearing " clatter " one, clamping element is opened fully, at this moment nail can be placed in the cavity volume 63, then discharge spanner 16 so that clamped of nail keeps independently, electric hammer is oriented to make nail adjacent with workpiece subsequently, loads onto to press switch 7 behind the power brick (not shown) and connect motor M and make hit piece 61 reciprocating motions.When the user pressed against electric hammer on the workpiece, the head of nail was impacted repeatedly by hit piece 61, thereby little by little nail was inserted in the middle of the workpiece.When the user just wants to stop to impact when clamping element is not yet opened, the user can pull toggle 21 drive sleeve pipes 8 to the right and move right together, perhaps directly press sleeve pipe 8 and move right, so that clamping element opens each other, thereby make nail can break away from electric hammer.Be inserted into gradually in the process of workpiece at nail, as shown in figure 10, when sleeve pipe 8 engages with workpiece, the user then need overcome spring 11 pressure so that clamping element open.This allows nail partly to enter workpiece before being released.Such as Figure 11 and shown in Figure 12, the lower end of sheath 9 comprises at least one projection 91, and when this projection 91 was pushed spanner 16 open, sheath 9 was pushed the projection 101 of both sides on the cutting ferrule 10 open in housing, so that main body 51 can be slided in housing.As shown in figure 12, when the end face 51a of main body 51 contacts with workpiece, clamping element is in a fully open position, and the user then need overcome the pressure of spring 12 so that the head of a nail can pass through clamping element, and lining 15 and impulse member 61 also can continue to impact nail by clamping element.As shown in figure 13, when lining 15 contacted with workpiece, the user then need overcome the pressure of spring 14 so that lining 15 all the time around the head of a nail, prevents that the head of a nail is stuck in clamping element and opens fully in the slit of rear generation.As shown in figure 14, then continue to impact nail, until nail is hammered in the workpiece fully.

This clamp mechanism comprises a locking mechanism, and after nail was hammered in the workpiece fully, projection 91 engaged with spanner 16, so that sheath 9 is locked in the clamping element fully open position.Put again a nail in cavity volume 63, then press lower ejector lever 16, so that clamping element repeats above-mentioned steps at cavity volume 63 interior clamped spiked, then can carry out impacting the second time nail.The lower end of sheath 9 can also be provided with another projection, so that sheath 9 can be locked in the another location, in this position, lining 15 exposes from sleeve pipe 8, increases the visuality of hit piece 61.At this moment, 611 positions of knocking that can be used as electric hammer are held in impacting of this hit piece 61, during work, along with workpiece to be processed is knocked in the straight reciprocating motion of hit piece 61, as strike tenon, strike brick etc., realize the Function Extension of this machine, and be not limited only to securing member is hammered in the workpiece.And those skilled in the art is understandable that sleeve pipe 8 and sheath 9 usefulness transparent materials such as transparent plastic etc. is made according to present embodiment, also can increase the visuality of hit piece 61.When the user saw the particular location of hit piece 61, the user just can be used as electric hammer with it, removed to knock workpiece to be processed.In addition, than the tingle period of the day from 11 p.m. to 1 a.m, " V " connected in star that arranges on sleeve pipe and the sheath also can increase the visuality of nail in clamping, is convenient to user's operation.The electric hammer that the present invention discloses is not limited to the described content of above embodiment and the represented structure of accompanying drawing.On basis of the present invention to the shape of member wherein and the apparently change that makes the position, substitute or revise, all within the scope of protection of present invention.

Claims (20)

1. electric hammer, comprise housing, motor, transmission mechanism, impact assembly, hit piece and clamp mechanism, described motor vertically is installed in the described housing, described transmission mechanism is by the bevel gear transmission and impact assembly and convert rotatablely moving of motor to described hit piece percussion action, described impact assembly comprise with described hit piece divided the impact block that contacts by impact portion, described clamp mechanism comprises sleeve pipe, at least two clamping elements and bias unit, it is characterized in that: described sleeve pipe drives described clamping element and moves between the position of open and close, described sleeve pipe is provided with groove, described clamping element slides in described groove, the primary importance of clamping element opposed slot, clamping element is closed, the second place of clamping element opposed slot, clamping element is opened.

2. electric hammer as claimed in claim 1, it is characterized in that described bias unit comprises the first bias unit and the second bias unit, described the first bias unit is used for impacting towards hit piece the direction off-set sleeve of element, described electric hammer also comprises a cutting ferrule, thereby the directive effect that described the second bias unit is used for impacting element towards hit piece is in described cutting ferrule setover described clamping element and described sleeve pipe.

3. electric hammer as claimed in claim 1, it is characterized in that being provided with the groove group at least two faces of described sleeve pipe, groove on each face is mutually symmetrical, described clamping element comprises drive part, described drive part places in the described groove, and described drive part can move along described groove.

4. electric hammer as claimed in claim 3, it is characterized in that described clamp mechanism comprises four clamping elements, be provided with the groove group on four faces of described sleeve pipe, groove on each face is mutually symmetrical, described clamping element comprises drive part, described drive part places in the described groove, and described drive part can move along described groove.

5. electric hammer as claimed in claim 1 is characterized in that described groove is set to broken line type.

6. electric hammer as claimed in claim 3 is characterized in that described drive part is removably mounted on the described clamping element.

7. electric hammer as claimed in claim 3 is characterized in that described drive part and described clamping element arrange all-in-one-piece.

8. electric hammer as claimed in claim 1 is characterized in that described clamping element comprises each or any combination of claw, spring, magnet, screw or chuck for holding element.

9. electric hammer as claimed in claim 1 is characterized in that when described clamping element is positioned at open position, forms a release areas, and described hit piece can be by described release areas.

10. electric hammer as claimed in claim 9 is characterized in that described clamp mechanism comprises a lining, and described lining can be by described release areas.

11. electric hammer as claimed in claim 10 is characterized in that described bias unit comprises the 3rd bias unit, the direction that described the 3rd bias unit impacts element towards the hit piece described lining of setovering.

12. electric hammer as claimed in claim 1 is characterized in that described clamping element can interlock.

13. electric hammer as claimed in claim 1 is characterized in that described clamp mechanism comprises a locking mechanism.

14. electric hammer as claimed in claim 13 is characterized in that described locking mechanism comprises at least one projection and spanner.

15. electric hammer as claimed in claim 14 is characterized in that described clamping element is positioned at open position after a described projection and the locking of described spanner.

16. electric hammer as claimed in claim 14 is characterized in that described lining exposes after a described projection and the locking of described spanner from sleeve pipe.

17. electric hammer as claimed in claim 1 is characterized in that described sleeve pipe is provided with a sheath.

18. electric hammer as claimed in claim 17, thereby it is characterized in that a toggle engages so that described toggle moves with described sheath with described sheath.

19. electric hammer as claimed in claim 17 is characterized in that described sheath and/or described sleeve pipe made by transparent material.

20. electric hammer as claimed in claim 17 is characterized in that being provided with groove on described sleeve pipe and/or the described sheath.

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