FR2460760A1 - HANDLE FOR STRIKING TOOL HAVING VIBRATION DAMPING MEANS - Google Patents

Abstract

THE HANDLE OF THIS HAMMER (OR OTHER TOOL) IS COMPOSED OF A RIGID HANDLE 22 SURMOUNTED BY A COLUMN 18 COMPOSED OF ELEMENTS 20 ANALOGUE TO VERTEBRA. ALIGNED PASSAGES IN THE VERTEBRATES FORM AN ELONGATED DUCT IN THE HANDLE. FIBERGLASS RODS COATED IN POLYESTER ARE THREADED THROUGH TWO OF THE PASSAGES AND FIXED RIGIDLY TO HANDLE 22 AT A FIRST END AND TO BODY 12 OF THE TOOL AT THE OTHER END. THE THIRD PASSAGE WHICH IS SPACED FROM THE TWO OTHERS TOWARDS THE PUNCHING HEAD 10, RECEIVES A STEEL ROD WHICH IS FIXED RIGIDLY TO THE BODY 12 BUT SLIDES IN THE HANDLE 22. THE HANDLE IS THUS FLEXIBLE AND CAPABLE OF DAMPING SHOCK CAUSED BY THE IMPACT OF THE BODY 12 ON A NAIL OR EQUIVALENT. THE FLEXIBILITY EXISTS ONLY IN ONE DIRECTION SO AS NOT TO HURT THE NAIL PULLER FUNCTION OF THE TIP 14 FORM AT THE OTHER END OF THE BODY.

Description

The present invention relates to the field of impact striking tools.

  hand. The most common example of this

  type of tool is the hammer. Although it constitutes an ins-

relatively simple, the hammer has been continuously improved and the classic hammer

with wooden handle and steel body has long since

  the predominance of more sophisticated versions.

Improvements to the hammer have been

oriented on various aspects, the most obvious of which is natural

  actually the connection between the body and the handle. However,

  there is another area in which people find a place

operations. This area is that of the importance of the shock transmitted by the hammer in hand. The shock transmitted to the hand following occasional and irregular use is not

  not usually cause concern to the user, it does not

  not seriously affect its comfort. On the contrary, those who use the hammer for prolonged periods, day after day, can consider as a very important progress the reduction of the transmitted shock. It is therefore desirable to reduce this transmission of energy from the body of the hammer to

the hand holding it.

  It has been found that the type of handle with which the hammer is equipped can be the cause of a large difference in the value of the shock suffered by the user. It can be expected, for example, that a hammer with a steel handle provides a significant reduction in shock compared to a hammer with

  wooden handle. In addition, there are hand hammers.

  fiberglass che in which the shock is frequently reduced compared to what is observed in the case of

  hammers with steel handle of the same dimension.

An object of the invention is to further reduce the shock transmitted to the user by a hand impact tool. Another object of the invention is to ensure this reduction of the shock by the use of a handle which is flexible but

  can be adapted to allow, if necessary,

ser a failure formed on the body of the hammer.

  These and other goals are reached below.

  the invention thanks to a hand-type striking tool, which

  takes a handle presenting the constitution of a green column

  tebral. This column is made up of a large number of elements

vertebra-like elements that are assembled to form

sea an elongated column, each of these vertebrae being per-

  cée a passage along the length of the column which forms with the passages of the other vertebrae an elongated conduit extending over the height of the column. Elastically flexible rod passes through the passage and extends

  beyond at least at one end of the column of vertebrae.

This column also includes means spaced from the ti-

  ge which prevent the relative rotation of the vertebrae with respect to each other around this rod. A striking tool body is rigidly connected to a first end of the elastically flexible rod and is thus returned to a rest position relative to the end of the column of vertebrae which is furthest from the body of the hammer. The

body can nevertheless change position relative to the ex-

  far end of the spine when the stem flexes. Each of the vertebrae can have a second passage which crosses it longitudinally in order to spare

a second elongated conduit in the column. The means will

aiming at preventing the relative rotation of the vertebrae can then comprise a second flexible rod which crosses the second elongated duct. The second rod then opposes

  the relative rotation of the vertebrae around the first ti-

  ge. The second rod is preferably elastically flexible.

  ble and rigidly fixed to the body of the tool and it can

  advantageously be of polygonal section.

  In a preferred embodiment of the invention,

  tion, the first rod is adjusted without play in the first

elongated duct.

  Normally, the first rod passes through the second end of the column of vertebrae and the tool further comprises a handle rigidly fixed to the end of this first rod which is furthest from the body. The second rod is connected by a fixed link, either to the handle or

  to the tool body and it is slidably mounted in the au-

  be of these two elements. This construction is opposed to the

  rotation of the vertebrae relative to the handle while

  putting a movement of the body relative to this handle.

  In the preferred embodiment the second rod is

  connected to the body by a fixed link and it is mounted

smoothing in the handle.

  According to another aspect of the invention, the hand striking tool comprises a tool body, which has a

first end and a second end. The first ti-

  elongated ge has an end rigidly fixed to the body of the tool, at a point situated between the two ends of this body and it is plastically flexible but practically inextensible in the longitudinal direction. The handle is

  rigidly connected to the end of the rod which is the most

  away from the body, the rod thus recalling the body of the

  til to make it take a rest position relative to the handle. When the body is in its rest position, a spacer extends between the handle and the body and presses on the handle and on the body of the tool, at a point located between the rod and the first end of this body. , but allows the part of the body on which the spacer

  leans away from the handle. The spacer is pra-

tically incompressible and consequently prevents the part of the body of the tool on which it rests from approaching the handle when leaving its rest position. The rod and the spacer cooperate in this way to allow the hammer body to tilt from its rest position towards its second end but prevent it from

  tilt from this rest position towards its first

first end.

  Ltentretoise can advantageously understand the

appears from the column of vertebrae assembled so as to form-

  sea a column of great height, of practically incompressible vertebrae. This column includes a first and a

second terminal vertebrae located at its ends. Cha-

one of the vertebrae is pierced with a passage which extends lengthwise of the column so as to form with

  the other passages a very long conduit which crosses

stands the column. The rod extends into the elongated passage. The first terminal vertebra is pressed against the handle and when the body of the tool is in its rest position the second terminal vertebra is pressed against this body, at least between the rod and the first end of the body, to ensure contact between the body and the spacer. In the

preferred embodiment, the second rod is essential-

also composed of tool steel with elastic hardening and the

  it comprises two first stems spaced in a direction approximately perpendicular to the fictitious line which extends from

  to each other of the ends of the tool body.

  The invention can be applied in a hand striking tool comprising a tool body which has a first end and a second end, a handle,

a first elongated and flexible rod including a first ex-

  end is rigidly fixed to the body of the tool, between the

  ends of this body, while the other end is fi-

rigidly attached to the handle, the second elongated and flexible rod extending from the handle to the tool body, between the

first rod and the first end of the body and being mon-

sliding tee in one or each of the two elements

killed by the handle and the body, and vertebrae being assembled

whipped to form an elongated column which extends from the body to the handle, each of the vertebrae being traversed by a first passage and a second passage which extend lengthwise of the column to form a first and a second elongated passage through which the first rod and the second rod are threaded, at least

one of these two rods being elastically flexible.

  The characteristics and advantages of the invention

  will appear more clearly during the description which

go follow. In the accompanying drawings, given only as

example,

- Fig. 1 is a view in vertical elevation, with partial section, of a hammer implementing the invention;

  - Fig. 2 is an exploded view showing parts

  parts of an example of a spine according to the invention; - Fig. 3 is a section along line 3-3 in FIG. 1; - Fig. 4 is a section along line 4-4 of FIG. 1; - Fig. 5 is a vertical elevation view of the handle of another embodiment of the invention; Fig. 6 is a plan view of the handle of FIG. 5; - Figs. 7, 8 and 9 are plan views of other embodiments of the vertebrae; - Fig. 10 is an elevation view of the vertebra

shown in FIG. 9.

  Fig. 1 represents a carpenter's hammer

  both implement the invention. This hammer comprises a body 12 of conventional shape which has at one end the usual impact surface or head 10 and, at the other end a split purl 14. As is also conventional, a sleeve 18 is provided between the two ends of the body to connect this body to a handle 22. However, the handle 18 of the hammer

  according to the invention is clearly different from that of the dis-

  positive of the prior art, in that it is composed of a column which is flexible so as to reduce the transmission of shocks. This handle allows however to use

  suitably the breakdown of the hammer body.

According to the invention, the handle 18 comprises a cer-

number of vertebrae 20 which are assembled to form

  a column extending from the handle 22 to the body 12. The

  truction of this column is illustrated in FIG. 2, on which are represented two vertebrae 20 which are assembled

wheat on rods 36 and 38. The vertebrae 20 are practical-

incompressible and are normally molded from one of various tough plastic materials such as

  polyamide, polycarbonates, polyacetals, polyethylene

  lene, polypropylene and acrylonitryl / bu terpolymers

  tadiene / styrene. In particular, satisfactory results

have been obtained with soft elements or vertebrae

  strips in a polyamide resin loaded with glass fibers in

  a proportion of 20%. As shown in Fig. 2, each worm-

  tèbre is pierced with several openings. 32 holes for-

  irregular me do not play a special role in the pro-

finished product but are normally intended to give the piece

  molded 1 relatively uniform thickness recognized as advanced

tgeuse by plastics technicians. A passa-

  ge 30 of square section is provided in the region of the side of the vertebra which is closest to the head 10. Two other passages 34 are provided in the region of the vertebra which is the

  closer to the failure and, when the vertebrae are assembled

  these passages are aligned to form three conduits

lying down.

  As shown in Fig. 2, a rod 36 is threaded into the elongated conduit formed by the passages 30 while rods 38 are threaded into the elongated conduits formed

  through the passages 34. The rods 38 are preferably elements

  elements extruded by drawing in glass fibers, carbon or

  boron, coated in a suitable resin such as a resin

  polyester, epoxy or silicone sine and these rods are therefore analogous to the materials used for fishing rods

  modern. The rods made of continuous glass fibers

-35 openings of a polyester resin turned out to be quite ap-

  properties. In a preferred embodiment, the rod 36 is made of tool steel with elastic quenching. It is obvious that

  the three rods are elastically flexible.

  The assembly of the body and the handle to the spine 18 can be understood by considering Figs. 3 and 4, in combination with Figs. 1 and 2. FIG. 3 is a section along line 3-3 which crosses a fiberglass post 17 joining a terminal vertebra 20 but having

in section the shape shown in Fig. 3. The rods ex-

  trudées 38 are glued in cavities of the post 17. The rod 36 is fixed in another cavity. Although it is not

shown in the drawings, the rod 36 is normally molar

  ted at this end to enhance the effectiveness of the link. Figs. 1 and 4 show that the handle 22 has a relatively conventional shape but has recesses 24 and 26 (Fig.l) intended to receive the rods 36 and 38. Although the three rods are received in the handle 22, only the rods 38 are fixed on it. The rod 36 is simply slidably mounted in the handle 22. In fact, it can be

  desirable to lubricate the recess 24 to improve the bond

  movement of the rod 36 in the handle.

  As can be seen in Fig. 6, space 28

  is left free at the end of the recess 26 to receive

see the excess of the adhesive agent.

  When using the tool the head 10 hits the nail or other target in the usual way. However,

  elastically flexible rods 36 and 38 of the vertebral column

  allow the body 12 of the hammer to move relative

port to the handle 22e In this movement, the body 12 inclines

ne to take the position represented at 16. In this po-

  sition, one end of the body 12 has moved slightly away from the handle 22 while the other end has moved closer to this handle. If the rod 36 were rigidly attached to the handle, this tilt could not occur. Although all of them are flexible, none of the rods is practically compressible or stretchable in the direction

longitudinal. However, as indicated above, the ti-

  ge 36 is simply sliding in the handle 22 so that it can slide relative to the latter at the time of the impact and that it allows the suggested tilting movement

by reference 16.

  Although it is not clear why the arrangement shown in Figs. 1 to 4 reduces the vibrations, it is sufficiently clear that part of the

initial shock is suppressed by bending the spine

  18. Naturally, this energy is accumulated in a certain proportion in the elastically flexible rods 36 and 38 but it is estimated that the displacement that the vertebrae

20 must perform relative to each other

  probably due to the dissipation of a certain amount of energy4 Furthermore, it should be noted that the rods are relatively free in the vertebrae 20 and that an elastic bend is probably caused at the interface

  between these rods and the vertebrae when the latter are

  place. Finally, there occurs between the rod 36 and the vertebrae, a certain relative movement which contributes to energy losses by friction. The amortization effect is

most likely provided by a combination of these factors.

  Whatever the reason for the cushioning effect

Tests have shown that the shock suffered by users

teurs of the hammer according to the invention is significantly lower than that received by users of known hammers. Tests were carried out in which hammers similar to that shown in FIGS were compared. 1 to 4 hammers

  with a wooden, steel or fiberglass handle.

  In a test, a hammer of 453 g of each type was placed in a pendulum, with an accelerometer fixed to its handle and the accelerometer recorded the value of the shock observed at the end of the handle. The same test is repeated with 624 g hammers. The results of these tests are shown in the two tables below: Shock on Shock N hammer according to the invention (g) I0 il Average 8.8 (g) Shock on hammer with fiberglass handle (g) 17, 4 (g) Shock on hammer with steel handle (g) 22.8 (g) Shock on hammer with wooden handle (g) 48.4 (g) Average 21.6 (g) 58.0 (g) 69 , 7 (g) 31.5 (g) It is clear from an examination of these results

  that we get a significant reduction in shocks with the

  teaux produced according to the invention.

  Despite the flexibility of the spine according to the invention, the tip 14 of the hammer body 12 can still be used in the normal way. This is due to the

  makes the column of vertebrae behave like an

  rod to prevent the hammer body from tilting di-

  rection of the head 10. The body 12 can tilt towards the purlin, the front end of the hammer being able to move away from the handle - because the rod 36 is simply slidably fitted in this handle 22. On the contrary, the column

  vertebrae which are practically incompress material-

  sible, prevents the body from approaching the handle notably. The rods 38 which are rigidly fixed both to the handle and to the body 12 of the hammer prevent the side of this body which is closest to the purlin 14 from moving away

of the handle 22. In this way, the body 12 cannot tilt

  ner forward and purlin 14 can be used in the

normal lesson.

  Although the principle of the invention was illus-

  very up to now by an exemplary embodiment which has been tested and has been found to provide the important advantages mentioned above, it will be obvious to those skilled in the art that the invention can be adapted to other applications

  while still bringing many of these benefits.

  In particular, it is obvious that there is no need for a

  use two rods rigidly fixed at their two ends.

  Figs. 5 and 6 show a handle constituting a variant

  embodiment, in which only one rod is rigidly fixed

  dement at its two ends. The recess 26 which receives the

  extruded rod is shown deeper than the recess 24.

  Of course, this is not a necessary condition

  but it is considered desirable to have a surface area

  that of relatively large length for the fixed rod. he

The shape of the vertebrae can of course be modified

  shown significantly, Fig0 7 represents another form

  me possible. In this embodiment of the hammer, the fixed rod has a square section, as suggested by the shape of the passage 34 intended for this rod. Fig. 7 also shows that the

  openings 32 can also have a different shape.

Fig. 8 relates to another variant, the same

  reference designating corresponding elements.

  It should be recalled that the invention is not limited to the illustrated carpenter's hammer or hammers in general. It’s obvious that any hand punching tool,

  such as a pick or an ax, can benefit from the invention.

  Furthermore, the unidirectional bending characteristic

  is not necessary to obtain the benefit of absorb-

tion of shocks. For example, Figs. 9 and 10 represent a vertebra which can be used in a tip hammer

round with heads at both ends of its body.

  As in the other figures, the reference 30 designates

  a passage in which a sliding rod is threaded

  say that the passage 34 receives a fixed rod. The hammer used

  sant this arrangement is intended to tilt in both directions and this is achieved by the presence of surfaces 40

  slightly inclined on the vertebrae 20. With this arrangement-

  the vertebrae perform most of their functions

  normal but do not behave like a spacer.

The faces 40 of each vertebra converge at their two ex-

hoppers. The resulting play between the vertebrae allows

  are trying to tighten the spine from one side

  stretching each other. The shock absorption effect is

  core obtained but, sag can now occur

  re in both directions and is no longer limited to one side.

  It can be posed opposite Fig. 10 the question

  to know if it is necessary to provide sliding rods

  tes in passages 30. The answer is that these rods are only

  rigorously necessary in any of the embodiments

tion but that they add a certain rigidity which prevents

  the spine to be too flexible; the sliding rods

  health are normally elastically flexible and therefore tend to increase the rigidity of the column. However, the use of a single elastically flexible rod having appropriate dimensions could give the assembly the

stiffness required. The use of a second rod has also

  The effect of opposing the relative rotation of the di-

  vertebrae as well as the spine and the body of the tool. It is likely that small amplitude rotational movements would not pose functional problems, but it is believed that the user would find this

annoying relative movement.

  If we want to maintain the alignment of the vertebrae without using a second rod, we can use the shape of

  embodiment shown in Figs. 11 and 12. The same nu-

  Reference numbers that previously are used in Figs. 11 and 12 to designate similar parts of the structure,

but a reference 50 designates a J-shaped rod which

  the only rod used in the embodiment of Figs. 11 and 12. FIG. It shows a handle 22 which has an elongated cavity 44 in which the J-shaped rod 50

is housed. A rivet whose head is designated by the reference-

  this 46 is fixed in the handle 22, the rod 48 of this rivet is

  both threaded into the hook of the J-shaped rod to hold this rod 50 in position in the handle 22. As in the previous embodiments, the rod is engaged in a stud 17 to which it is rigidly fixed to maintain the tool body in place. In this embodiment, the single rod, which is rigidly fixed at its two ends, is normally made of tool steel with elastic quenching instead of being made of an extruded plastic material.

  by stretching like the fixed rods of other forms of realization

  station. Naturally, the fixed rods of other forms of

  realization, could be in steel and the sliding rods

  in extruded plastic. However, in the embodiment of Figs. 11 and 12, steel is chosen

  because most of the stiffness of the handle

teau must be provided by the single rod 50 and that this role is more easily ensured by a steel rod.

  In this embodiment, the rotation relates

  tive of the vertebrae with respect to each other as well as

  relative to the handle and body of the hammer are prevented

  chées not by a second rod but by the presence of ribs 42 on the upper surface of the handle 22 as well as on that of the vertebrae 20. These ribs 42 stembooit in complementary grooves 43 of the lower surface of the vertebrae and such an arrangement opposes rotations

  relative. We can therefore use, to avoid having to pre-

see several rods, ribs or other protrusions, -

  and complementary grooves or other cavities. Natural-

  Lement in some applications, it is desirable to provide two rods, from the point of view of the rigidity or security of the fixing of the hammer body but, in the

When it is convenient to use only one rod, the ar-

storage of Figs. 11 and 12 is a simple provision

  which provides the advantages of the invention.

  Figs. 11 and 12 illustrate another characteristic

  tick that can be included in each of the embodiments

  sation represented. Fig. 12 shows a clearance 52 arranged in

  be the rod 50 and the wall of the conduit in which this rod is threaded. In reality, the rod 50 is adjusted without play in

  the passage, as can be seen in FIG. 11 but this not-

  sage diverges at its two ends. Since in

* many cases, the vertebrae are designed to be practical-

  incompressible, so that they behave like a spacer, the adjustment of the rod without play on any

  the length of the duct can give the handle a stiffness

  less than what is actually desired. The arrangement shown in Figs. 11 and 12 provides an adjustment that

allows relative displacement between the vertebrae and a friction

  between the stem and the vertebrae but does not interfere excessively

the deflection of the stem. Naturally, this

  configuration of the duct section is not essential

  ble and its use depends on various parameters such as the nature of the material of the stem and that of the vertebrae and whether the column of vertebrae is used or not

  as a spacer. It can also be expected that more

  very parameters such as the mass of the body of the tool and the length of the handle have an influence on the advantage which one can have to give to the passages the configuration represented

in Figs. 11 and 12.

  It follows from the above that the invention provides

  makes a really new provision for a punching tool

  hand, which represents a significant technical advance. The am-

  plitude and the duration of the shock which one undergoes by using the hammers constructed in accordance with the invention are reduced by the characteristics of flexibility and damping inherent in the invention, moreover, this flexibility

  can be obtained in a sacrificial carpenter's hammer

pride the efficiency of the purlin function.

Claims (14)

R E V E N D I C A T I O N S   1 - Hand striking tool characterized in that it comprises: an elongated assembly in the form of a spinal column (18) which comprises several vertebrae (20) assembled to form an elongated column and each crossed by a passage (34 ) which extends along the length of the column, to form in the column an elongated conduit which crosses it; an elastically flexible rod (38) which is threaded through the elongated passage and emerges at least at one end of the column of vertebrae; and means spaced from the rod for preventing relative rotation of the vertebrae around the rod; and a striking tool body rigidly fixed to the emerging end of the elastically flexible rod, and returned to a rest position relative to the end of the column of vertebrae which is the most distant from the body, but capable of undergo, during a deflection of the rod, a variation in position relative to this end of the column of vertebrae. 2 - Tool according to claim 1, characterized in that each of the vertebrae (20) has a second passage (30) which crosses it longitudinally to form in the whole of the column a second elongated conduit   crossing this column, the means that oppose the ro-   tation comprising a second flexible rod (36) which is   spun in this second elongated conduit.   3 - Tool according to claim 2, characterized in that the second rod (36) is elastically flexible and   is rigidly fixed to the body (12) of the tool.   4 - Tool according to claim 2, characterized in that the second rod (36) has a polygonal section.   - Tool according to either of Claims 1 and 2,   characterized in that the first rod (38) is adjusted without   game in the first elongated pass.   6 - Tool according to claim 2, characterized in that the first rod (38) emerges at the second end of the column of vertebrae (20) the tool further comprising a handle (22) rigidly fixed to this end of the   first rod which is furthest from the body (12) of the til, and in that the second rod (36) is rigidly fixed to one of the two elements constituted by the handle (22) and the body (12) of the tool and is slidably mounted in the other   of these two elements, which prevents rotational movements tion between the vertebrae (20) and the handle while allowing movement of the tool body relative to the handle. 7 - Tool according to claim 6, characterized in that the second rod (36) is rigidly fixed to the body (12) of the tool and is sliding in the handle (22). 8 - Tool according to one of claims 6 or 7,   characterized in that the second rod (36) is elastically flexible. 9 - Tool according to claim 2, characterized in that the first rod (38) is extruded from a material essentially composed of continuous glass fibers   coated in polyester resin, the second rod being mainly in tool steel with elastic hardening, and in that the vertebra-shaped elements are molded in a   material essentially composed of a polyamide resin char- glass age. 10 - Hand impact tool, characterized in that it comprises: a tool body (12) which has a first end and a second end; an elongated rod (38) one end of which is rigidly fixed to the body of the tool, at a point between the ends of this body, this ti- ge being elastically flexible but practically inextensi-   ble in the longitudinal direction; a handle (22) rigidly fixed to the end of the rod which is furthest from the body (12), this rod thus tending to place the body of the tool in a rest position relative to the handle and means (18) forming a spacer which, when the tool body occupies the rest position, extend between the handle and the body to rest on the handle and against   the body, between the stem and the first end, but per-   put to the part of the tool body against which then the spacer Q.8) to move away from the handle (22), means (20) forming a spacer (18) being practically   compressible and consequently preventing the part of the body (12) against which they rest from approaching the body from the rest position, the rod (36) and the spacer means (18) thus cooperating to allow the body to tilt towards its second end from its rest position but to prevent it from tilting towards   its first end from this rest position.   II - Tool according to claim 1, characterized   in that the spacer means comprise a set ble of vertebra-shaped elements (20) assembled to form sea an elongated column practically incompressible, and   thus comprising a first and a second ver-   terminal shafts situated at its two ends, each of the vertebrae being traversed by a passage (34) which extends in the lengthwise direction of the column so as to form in the column an elongated passage which crosses this column,   and in which the rod (36) is threaded, the first vertebra-   bre terminal being pressed against the handle (22) while the second is pressed against the body when this body (12) is in the rest position, at least in the region between the rod and the first end of the body,   to establish support against this body and the means mant spacers (18).   30. 12 - Tool according to claim 11, character- rised in that each of the vertebrae has a second passage (30) which crosses it in the direction of the length of the column to form a second passage in the column   elongated, the tool further comprising a second flexible rod xible (36) which is threaded into the second elongated passage, and thus prevents the vertebrae from rotating relative to each other to others around the first rod (38).   13 - Tool according to claim 12, characterized in that the second rod (36) is rigidly fixed to one of the two elements constituted by the handle (22) and the body   (12) of the tool and slides in the other of these two elements.   14 - Tool according to claim 13, characterized in that the second rod is rigidly fixed to the body (12) and slides in the handle (22).   15 - Tool according to one of claims 12, 13 and 14, characterized in that the second rod (36) is elas- tically flexible.   16 - Tool according to claim 15, characterized in that the second rod (38) is essentially composed of tool steel with elastic hardening. 17 - Tool according to claim 16, characterized in that it comprises two first rods (38) spaced one from the other in a direction approximately perpendicular to   an imaginary line that extends from one to the other of the ex- tool body hoppers.   18 - Hand striking tool characterized in that it comprises: a body (12) having a first end and a second end; a handle (22); a first flexible elongated rod (38) of which a first end is rigidly fixed to the body of the tool, at a point situated between the ends of this body, while its other end is   rigidly attached to the handle; a second rod (36) extending   flexible hose that extends from the handle to a point on the body   of the tool located between the first rod and the first end   mite of this body, which is slidably mounted in at least one of the two elements constituted by the handle and the body, at least one of the two rods being elastically flexible;   several vertebra-shaped elements (20) which are assembled   wheat to form an elongated column (18) going from the body of the tool to the handle, and are each crossed by a first passage (34) and a second passage (30) which extend in the direction of the length of the columns so as to form in the column a first and a second elongated conduits, the   first rod (38) and the second rod (36) being respective-   strung in the first and second passages lying down. -