US2864338A - Manually guided mechanical hammer - Google Patents

Description

Dec. 16, 1958 zlMMERMANN 2,864,338

MANUALLY GUIDED MECHANICAL HAMMER Filed May 3, 1954 5 Sheets-Sheet 1 FIG.

[NI INTO? Dec. 16, 1958 H. ZIMMERMANN 2,864,338

' MANUALLX GUIDED MECHANICAL HAMMER Filed May 3, 1954 5 Sheets-Sheet 2 IN VEN 7' 0R Dec. 16, 1958 ZIMMERMANN 2,864,338

MANUALLY GUIDED MECHANICAL HAMMER Filed May 3, 1954 V 5 Sheets-Sheet 3 INVENTOP Dec. 16, 1958 H. ZIMMERMANN MANUALLY GUIDED MECHANICAL HAMMER 5 Sheets-Sheet 4 Filed ma 3. 1954 PVC-Z5 INKS/V70? Dec. 16, 1958 I H. ZIMMERMANN 2,864,338

MANUALLY GUIDED MECHANICAL HAMMER Filed May 3, 1954 5 Sheets-Sheet 5 ll 63 M 6.6 l 6 INVENTOIP JQMW ' MANUALLY GUIDED MECHANICAL HAMMER Horst Zimmermann, Sprockhovel, Westphalia, Germany Application May 3-, 1954, Serial N 427 ,252

11 Claims. (Cl. 121- 36) The invention relates to manually guided mechanical hammers, more especially those hammers in which the striking partis driven by a medium under pressure, for example, compressed air. Such mechanical hammers are used for rivetting, for crushing rock in tunnelling, quarrying and mining operations for breaking up roads and for other purposes. n v

The manually guided mechanical hammers are generally provided at their rear end with a handle set at right-angles to the hammering direction, which handle is usually made of loop formation. The workman holds the hammer at the handle with one hand and forces it against the material, rock or the like to be worked,

while the other hand'grips the stem of cylinder of the hammer housing in which the striking part, for example, the striking ram of a con'ipressed air hammer, is guided. Operations "carried out with the known mechanical hammers equipped with a rigid handle consisting of steel or the like are very tiring and in certain circumstances are dangerous, to health. This is connected with the fact that the reeoil being set up with the acceleration of the striking parts has to be taken up by the hand or body of the workman, and also all high-frequency and lowfrequency oscillations, which are transmitted to the steel housing and the handle when the striking part comes into contact with the tool (for example, a rivetting set and the breaking chisel).

It is an essential object of the invention that the physical strain caused by these vibrations or oscillations on the workman who has to work with a mechanical hammer should bereduced to a harmless extent.

Recent investigations have shown that the tool, for example, the rive't'ting setor anvil of a mechanical rivetting hammer or the chisel of a chipping hammer, only transmits a small part of the energy imparted by the freely travelling plunger on impact to the workpiece or material being broken up, for example, rock or coal. It has been established that impacts of the hammer piston or ram, which take place with strong damping and with which therefore the tool transmits its energy in an immediately utilisable form to the part to be worked, alternate with impacts in which a considerable proportion of the energy remains in the tool as vibrations (bending and elongation) and are consequently not available for the work of rivetting or breaking down. Due to the vibration of the tool energised by the hammer piston, the said tool, when it comes into resonance with the (elastic) workpiece or th'elike which is also set in vibration by the impact, is lifted from the surface of the workpiece or' the like and accelerated opposite to the impact direction of the hammer piston, so that the next impact thereof is practically not transmitted at all from the tool to the workpiece or the like being handled. A damping of the vibrations in thetool and hammer housing has hitherto only been possible by physical effort of the workman, this being eflected by the workman forcing thehammer against the workpiece or the like while overcoming the recoil forces and thereby holding the anvil 'or cutting edge of the chisel against the workpiece, The recoil forces to be overcome are, however, considerable under certain circumstances (recoil impact), for example, when the oscillat'able structures coupled with one another are in resonance, and accordingly constitute a considerable physical stress.

The invention now follows the guiding prineiple' of carrying out the eohnection of the thre'e structures which are capable of vibrating, namely, the tool area-ample, chisel), the hammer cylinder and the body of the workman who is operating the mechanical hammer, wholly or in part by shaped elements of non-metallic orgahicsubstances, which substantially damp'the vibrations in the metal parts, the degree of damping being in a favourable relationship to the recoil elasticity of the materialus'ed for the coupling;

It has already been proposed elsewhere to provide springs or soft rubber elements, for example, in the form of a handle consisting of soft rubber, in'the force transmission path between the chipping hammer and the workman. The object of this step was intended to be the relieving of the workman from the recoil forces of the hammer by means of a soft suspension. However, soft rubber per se, i. e. in the unten'sioned condition, is not suitable for damping the vibrations in the mechanical hammers within the meaning of the invention. It has been shown that the working capacity with the hammet when springs or soft rubber handles are provided is considerably reduced, because the chisel or the like, despite strong pressure on the elastic har'i'dle, bounces on the workpiece on account of its large spring path, so that the number of impacts or blows with strong damping and high useful effect drops considerably as compared with the work carried out with an unsprung handle.

On the contrary, if the mechanical hammer is provided in accordance with the invention with a handle secured by interlocking on the end of the hammer h'ohsing, which handle consists of a material made from organic compounds and having a hardness (according to Shore) of about to 100, there is produced an effective damping with appreciable increase of the chiselling output on the workpiece and a corresponding large output of the workman operating the hammer without appreciable increase in muscular energy, 7

As an example of the synthetic polymeric organic material from which the damping connecting member may be made in accordance with the invention, it is possible to refer primarily to isocyanate-polyester addition products. However, it is also possible to use other polycondensation products, polymerisation products or polyaddition products, for example, polyurethane. The said materials may be manufactured in such manner that they possess the damping properties prescribed by the inv'e'r'ition. In addition, they also have a high resistance to wear and are resistant to oil and petrol. Moreover, the resistance to aging of the materials is very favourable.

Such materials are known per se. The importance thereof as a structural material for the handle of compressed air hammers or the like was, however, not known. On account of their hardness, they had even been considered as disadvantageous for those purposes in which it is important to damp mechanical vibrations. It was not to be foreseen that, in contrast thereto, the use of these materials for compressed air hammer handles according to the invention provides a considerable technical advance or improvement as regards the increase in the working output. v

In special cases, it is possible for the material used, for example, for the handle to be provided with an addition of parafiin, which smooths the surface of the body der head or the like.

stances.

The preferred embodiment of the invention consists in that the complete handle of the hammer is made of the said organic material, for example, the connection of the vibratable hammer cylinder to the hand of the workman is effected by a handle which damps the vibrations and which is connected by interlocking fit to the metal cylin- The invention may also be used with advantage for the coupling between the chisel and the cylinder casing of the hammer in order also at this position to prevent or reduce the transmission of vibrations from the chisel to the housing of the mechanical hammer.

The connection between the handle and the housing of the mechanical hammer may be efiected in various ways.

For example, in accordance with the invention, it i possible for the hammer housing to be provided with a rearward projection which is arranged substantially parallel to its longitudinal axis, a laterally extending projec- .tion being provided on the opposite side of the hammer.

The stem of the starting valve may be provided in the rearward projection. The rearwardly directed projection may, however, also be made hollow and be used for the supply of compressed air.

The connection between the handle and the hammer housing may, if a pourable material is used for the handle,

.be produced by the fact that the handle is cast on to the housing consisting of steel or another metallic material, the non-metallic material of the handle enclosing projections or attachments of the hammer housing.

Finally, the invention is also concerned with the pro- .vision of a protective cap embracing the handle and perhaps the hammer housing, which material encloses the handle and covering that hand of the workman which is gripping the handle.

Embodiments of the invention are illustrated by way of example in the drawing, but the invention is not restricted to such embodiments.

In the drawing:

Figure 1 is a section through the handle and also that part of the cylinder housing of a rivetting hammer which is directly connected thereto.

Figure 2 is a similar'section through the handle and cylinder head of a chipping hammer.

Figure 3 is a side elevation of the chipping hammer according to Figure 2.

Figure 4 is a side elevation of a mould for casting the handle on to the hammer housing.

Figure 5 is a side elevation of the arrangement according to Figure 4, being partly a section on the line V-V of Figure 4.

Figure 6 is a side elevation of the protective cap.

Referring to Figure 1, the cap 1 is provided which closes the rear end of the working cylinder (not shown) of a rivetting hammer. The cap 1 is screwed by means of a screw-thread on to the end of the cylinder.

Arranged in the cylinder of the rivetting hammer in the usual manner is an impact piston which is influenced by a medium under pressure. These parts of the cylinder and the impact piston and the other parts of the rivetting hammer are not shown, since they are well known to a person skilled in the art and the construction thereof in detail is not alfected by the invention.

Provided on the cap 1 is a rearwardly extending union 2 which is formed with an internal screw-thread. The

,supply pipe for the pressure medium which drives the impact piston is screwed into the union 2. The pipe union 2 is in communication with the interior of the cylinder head 1 by way of the ducts 2a and 2b. The outlet end of the duct 2b is controlled by the valve 3, which is displaceable in a cavity in the cap or head. Under the pressure of the pressure medium, the valve 3 is forced against its seating 3a, so that the pressure medium is not able to flow unintentionally into the internal space of the cylinder head 1.

Provided on that side of the cap 1 which is opposite the union 2 is an attachment 6 formed with a horizontal bore 10 extending transversely of the cylinder axis. Engaging around the attachment or projection 6 is one end of the curved handle 7 which is made of synthetic polymeric organic material such as polycondensation or polyaddition products. The handle 7 fits tightly against the rounded surface 9 of the projection 6 and is secured in its position by a pin which is pushed through the bore 10 and extends through the arm 8 of the handle 7.

Provided at the other end 16 of the handle 7 is an opening with which the handle fits tightly around the union 2 provided externally with a screw thread or other projections.

The handle 7 is' therefore fixed to the projections 6 and 2 of the cylinder cap and may when required be removed from these projections after withdrawing the pin inserted through the bore 10.

Provided in one arm 8 of the handle 7 is a substantially arcuate passage in which is provided a suitably curved tube section 14. The. curved pin 15 is adapted to be displaced longitudinally in the tube section 14, the end of said pin bearing against the stem 13 of the valve 3.

The other end of the curved pin or plunger 15 is located in the region of a trigger member 4, which is mounted to pivot at 4a in a recess in the handle 7.

-When the trigger lever 4 is pivoted in the direction of the arrow, for example, by pressing from above on the trigger lever 4, the curved plunger 15 is displaced accordingly so that the valve rod 14 is moved towards the right and opens the valve 3. The pressure medium may then pass into the interior of the cylinder head 1 and operate the impactpiston until the trigger lever 4 is released.

The embodiment according to Figures'2 and 3 illustrates the handle of a chipping hammer which may be used, for example, for loosening rock or coal.

In Figure 2, 21 indicates the body of the conventional cap with which the cylinder housing of the hammer not shown in the drawing is closed at the upper end. The housing is provided laterally with a union 22 for the connection of the compressed air pipe. The connection between the union 22 and the interior of the cylinder cap 21 is controlled by the shut-01f valve 23 which may be lifted from its seating by means of the operating member 24 which is mounted to pivot about the pin 25.

On the side opposite the union 22, the cylinder cap 21 is provided with a projection in the form of a lug 26 which serves for the fixing of the handle 27. The said handle is formed in its extended arm 28 with a recess 29 corresponding to the shape of the projection 26, so that the arm 28 embraces the projection 26 on all sides. Serving to connect the arm 28 and the projection 26 is a pin 30 which is pushed through the opening of the projection 26 and the recess of the arm 28.

The other shorter arm 31 of the handle 27 is constructed in the manner of a tubular sleeve and is pushed over a union 32 in which the stem 33 of the valve 23 is displaceably mounted. The union 32 may be formed with undercut grooves so that the handle arm 31 adheres firmly thereto.

The top of the handle 27 is also formed, with a slotlike recess 34 for the operating member 24, said slot being so shaped that the member 24 is completely disposed in the recess 34 on opening the valve 23.

The method of fixing the handle in accordance with the invention, as described and illustrated, has the essential advantage that on the one hand a connection equal to operating stresses is ensured between the handle and cylinder head, and on the other hand the handle may carry out to a certain extent longitudinal and transverse bending movements corresponding to the possibly restricted yieldability of its non-metallic body without its firm grip on the cylinder head being impaired after having been in use for a relatively long period of time.

In order to prevent damage to the handle 27 consisting of organic material in the region of the extended arm 28, the handle is provided with a protective cap or guard 35 consisting of sheet steel or the like. The protective cap 35 embraces the arm of the handle on both sides by means of its flanges 35a. A recess 35b is provided in each of the sides of the cap 35, said recess having a groove in which is fitted a spring ring 350 which retains the head 30a of the holding pin 30 and secures it against slipping out unintentionally.

Figures 4 and 5 show how a handle according to the invention may be united by a casting operation with the hammer housing or the cylinder head. The principle of the manufacture consists in using the hand guard as part of a casting mould in which the handle is produced by the casting operation.

The cylinder head 41 which is shown in the drawing and which consists of steel is formed with a projection 43 on the side opposite the air inlet pipe 42 and has at the top a projection 44 which is in the form of a pipe union and comprises a peripheral recess 45.- The projection 44 is hollow and has extending therethrough the starting needle which is not shown and which is actuated by a trigger member arranged in the hammer handle.

The cylinder head 41 is so constructed that it may be connected to a two-part mould 46, 47, as shown in the drawing. The parts 46, 47 are centered by centering pins 48 and tightly connected with one another and with the cylinder cap 43 by means of a suitable pressure device or clamping means. The material to be castmay be poured into the cavity of the mould 46, 47 through alateral opening 4?.

As will be seen from the drawing, the mould is provided with a cavity which is indicatedon the drawing by the cross-hatching 51. The mould cavity corresponds first of all to the handle web which is gripped by the hand guiding it when the hammer is completed and to the twoarms, of which one extends through the lug-like projection 43 and the other surrounds the projection 44 extending upwardly from the cylinder head. A space 51' is also left inthemould 'beneaththe lug-like projection, said space forming a bead or rim which prevents the arm being withdrawn from the opening in the projection 43.

The plastic mass cast in the mould therefore forms a handle which is connected at one end by moulding to the projection 44 on the top of the cylinder head and at the other end to the lug-like projection 43.

After the casting operation, the mould 46, 47 is removed and the waste material 52 is cut off, and also the seam which is perhaps formed at the point of contact of the two mould halves d6, 47 is smoothed off.

The plastic body of the handle can then be used without further machining.

If the handle is also to be provided with recesses which serve, for example, for accommodating an operating memher and for introducing the starting needle, it is advantageous to provide the mould 46, 47 with suitable inserts which may be removed after opening the mould. This renders it unnecessary to follow up the casting of the handle with a number of additional working processes.

The handle in accordance with the invention is characterised by a durable and reliable connection between the non-metallic gripping part and the steel cap of the hammer cylinder. The handle is easy to manufacture and renders superfluous various machining operations which were hitherto necessary for preparing the hammer handle or the non-metallic gripping part.

Figure 6 shows a protective cap or guard of a pliable organic material. This protective guard may be detachably connected to the mechanical hammer in such manner that its engages around the handle and covers the hand holding: thelatter.- 7

As will be seen from Figure 6,v the guard consists of a part 6t which is bent'substantially to= U-shape and embraces the handle of the hammer (shown in broken lines):,insuch manner that the freeends- 67 of the part- 61 are directed in-the-direction of the connecting union 63' for the) pipe conveying the-medium under pressure As indicated at 64,- thepart 61 is fashioned in such manner that'it' closely surrounds the handle part of thehammer, Provided underneath-the hammer isa strap 65 into which are fittedpress-buttons 66 with which the strap 65 may bereleasably secured to the part 64. As indicated at 62,- the part 64 fits closely around the union 63. D

Figure 6 also'shows; that; the housing of the hammer may be provided witlj' a covering This consists of a curved part- 68 which is fixed bymeans" of straps 69 and 70 to the cylinder'housingfill'; g

The guard 61 and the part 68 may consist of any suitable organic materialwhichis flexible and has sufficient stability in order to protect the hand covered by the guard against falling rock.

1. In a manually guided mechanical hammer operated by a pressure fluid such as compressed air, the combinationof a metallic cap adapted to be fitted to the rearward end of the hammer cylinder, said cap having on opposite sides projections and a U-shaped grip portion connected on both its ends to the said projections, the body of said grip portion consisting of synthetic polymeric organic, non-metallic material, said organic nonmetalli c materialhaving a Shore degree of hardness betWeen SS and 100 g V U 2. In a manually guided mechanical. hammer operated by a pressure fluid such as compressed air, the combination of a metallic cap adapted to be fitted to the rearward end of the hammer cylinder, said cap having on one side a union-like projection extending rearwards the cap, said cap having on its side opposite to said unionlike projection a projection in the form of a lug, and a U-shaped grip portion connected on both its ends to the said projections, the body of said grip portion consisting of synthetic polymeric organic, non-metallic material, said organic non-metallic material having a Shore degree of hardness between and 100.

3. In a manually guided mechanical hammer operated by a pressure fluid such as compressed air, the combination of a metallic cap adapted to be fitted to the rearward end of the hammer cylinder, said cap having on opposite sides projections and a U-shaped grip portion, said grip portion having on one end an opening fitting around one of the projections of said cap, said grip portion having on its other end a recess adapted to being engaged by the other projection of said cap, the body of said grip portion consisting of synthetic polymeric organic, non-metallic material, said organic non-metallic material having a Shore degree of hardness between 85 and 100.

4. In a manually guided mechanical hammer operated by a pressure fluid such as compressed air, the combination of a metallic cap adapted to be fitted to the rearward end of the hammer cylinder, said cap having on opposite sides projections and a U-shaped grip portion connected on both its ends to the said projections, the body of said grip portion consisting of synthetic polymeric organic, non-metallic material, said organic nonmetallic material having a Shore degree of hardness between 85 and 100, an operating member or trigger arranged in a recess of said grip portion, a metallic pin pushed through bores of said grip portion and extending through said recess, said operating member or trigger mounted to pivot about said pin, and plunger extending through a recess of said grip portion, said plunger adapted to transmit power from said operating member or trigger to the shut-off valve of the hammer.

5. In a manually guided mechanical hammer operated by a pressure fluid such as compressed air, the combination of'a metallic cap adapted to be fitted to the rearward end of the hammer cylinder, said cap having on opposite sides projections and a U-shaped grip portion connected on both its ends to the said projections, the body of said grip portion consisting of synthetic polymeric organic, non-metallic material, said organic nonmetallic material, having a Shore degreeof hardness between 85 and 100, an operating member or trigger arranged in a recess of said grip portion, a metallic pin pushed through bores of said grip portion and extend ing through said recess, said operating member or trigger mounted to pivot about said pin, an arcuate tubular element embedded in said grip portions, an arcuate plunger arranged slidably in said arcuate tubular element, said plunger adapted to transmit power from said operating member or trigger to the shut-offvalve of the hammer. p j

6. In a manually guided mechanical hammer operated by a pressure fluid such as compressed air,-the combination of a metallic cap adapted to be fitted to the rearward end of the hammer cylinder, said cap having on one side a union-like projection extending rearwards the cap, said cap having on its side opposite to said unionlike projection a projection in the form of a lug, and a U-shaped grip portion connected on both its ends to the saidprojections, the body of said grip' portion consisting of synthetic polymeric organic, non-metallic material, said organic non-metallic material having a Shore degree of hardness between 85 and 100, and a metallic protectiveguard fitting over said end of the grip portion which is provided with a recess engaged by the one projection of said cap.

7. In a manually guided mechanical hammer operated by a pressure fluid such as compressed air,'the combination of a metallic cap adapted to be fitted to the rearward end of the hammer cylinder, said cap having on opposite sides projections and a U-shaped gripportion connected on both its ends to the said projections, the body of said grip portion consisting of synthetic polymeric organic, non-metallic material, said organic non-metallic material having a Shore degree of hardness between 85 and 100, an operating member or trigger arranged in a recess of said grip portion, a metallic pin pushed through bores of said grip portion and extending through said recess, said operating member or trigger mounted to pivot about said pin, and plunger extending through a recess of said grip portion, said plunger adapted to transmit power fromsaid operating member or trigger to the shut-off valve of the hammer, the body of said operating member or trigger consisting of an organic, non-metallic material the Shore hardness of which is etween 85 and 100.

8. In a manually guided mechanical hammer as called for in claim 1 in which the grip portion is cast with interlocking fit on the metallic cap.

9. In combination with a mechanical hammer housing operable by fluid pressure, a handle, and means connecting the handle to the housing, said handle being termed of synthetic polymeric organic, non-metallic material having a Shore degree of hardness between 85 and 100, for damping vibrations transmitted to the hands of the operator.

10. A metallic housing for a mechanical hammer operable by fluid pressure, said housing having spaced projections thereon, a handle formed of synthetic polymeric organic, non-metallic material having a Shore degree of hardness between 85 and 100, and means for casting the handle to the housing and to said projections.

11. A metallic housing for a mechanical hammer operable by fluid pressure, said housing having an air inlet on one side and a projection on its opposite side, said housing having a tubular projection on the top thereof, a handle formed of synthetic polymeric organic, nonmetallic material having a Shore degree of hardness between 85 and 100, and means for casting the handle to the housing and to said projections.

References Cited in the file of this patent UNITED STATES PATENTS 1,832,811 Jowett Nov. 17, 1931 2,425,245 Johnson Aug. 5, 1947 FOREIGN PATENTS 805,266 Germany Mar. 10, 1951

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