WO2014188459A1

WO2014188459A1 - Percussion tool for demolishing hammer

Info

Publication number: WO2014188459A1
Application number: PCT/IT2014/000127
Authority: WO
Inventors: Andrina GIOVANNI
Original assignee: Corimag S.R.L.
Priority date: 2013-05-20
Filing date: 2014-05-13
Publication date: 2014-11-27
Also published as: ITTO20130402A1

Abstract

A percussion tool (1) is described, for a demolishing hammer for perforations, demolitions or excavations, comprising an elongated body having: a first portion (3) aimed to be connected with the demolishing hammer and made of a first material; and a second portion (5), opposite to the first portion (3), which includes a working end (7) and is made of a second material different from the first material; such first and second portions (3, 5) are adapted to mutually make a coupling of the male-female type; each of the first and the second portions (3, 5) is shaped, in its respective end (9, 11) adapted to make, such male-female coupling, with a cross section whose shape is at least triangular; and the tool (1) is equipped with transverse holding means (14) for the first and the second portions (3, 5).

Description

PERCUSSION TOOL FOR DEMOLISHING HAMMER

The present invention refers in general to percussion tools, which can be used for perforation, demolition or excavation operations.

In particular, the invention deals with a percussion tool for a demolishing hammer of the type defined in attached claim 1.

Known percussion tools of the type mentioned above comprise a first portion, which, during its operation, is housed at least partially inside the hammer, and a second portion which includes a working bit. Normally, such tools are manufactured in a single piece of a material, typically steel, chosen in order to satisfy a compromise between two opposite needs. In fact, the first portion of these tools, whose upper end is cyclically subjected to very strong impacts due to the percussion action performed by a beating mass moving inside the hammer, requires a medium hardness and a high resistance to flexure and impacts, and therefore a good elastic resistance. The second portion of such tools, which is subjected to impacts against the material to be demolished, requires a high hardness and toughness and a high resistance to hot wear.

Since such known tools are made of a single piece, steel used for making them is chosen in order to be able to simultaneously satisfy the requirements required for both portions, and therefore has no features which are wholly optimum neither for the first, nor for the second portion. In particular, for the whole tool, steels are used which are alloyed with elements such as nickel, molybdenum, chromium, vanadium and similar metals, many of them, being rather costly, affect the total tool cost.

It would instead be desirable to be able to bave available tools of the type defined above, whose material has different features for each portion, so that the two portions are adapted to support the types of specific stresses to which each one of them will be subjected in use.

As an approximation, it can be deemed that the first portion of the tool provides for a 85% contribution in weight, while the second portion, composed of the working end, provides a contribution for about 15% in weight. The two tool portions could be made separately with different materials, each one chosen to optimally support its related stresses. In this way, the first portion could be made with a chromium-molybdenum or chromium-manganese alloyed steel, relatively inexpensive, while the second portion could be made with a highly specialized steel, with high resistance to hot wear, for example alloyed with tungsten and cobalt, and therefore relatively more expensive, but only as regards a small part of the tool .

Alternatively, the same steel could be used, but subjecting it to different heat treatments.

In this way, highly better tool performances could be obtained, together with greater reliability and length of use, at a lower cost than the one required to make the tool entirely with a high performance steel alloy.

There remains anyway a problem, whose solution is not easy, to be able to guarantee a connection of such two portions which is rigid, stable in time and reliable. In particular, the most common types of connection, for example of the screw and nut screw type (as disclosed in BE-A-440 648), are absolutely not adapted to resist in time to the high impulse stresses to which a tool of the type mentioned here is subjected, not being even suitable to win the applied unscrewing forces.

Other known solutions (for example EP-Al-1 174 225) are related to tool bits for precision or numerically controlled workings, thereby subjected to much lower stresses with respect to the tools for perforations, demolitions or excavations (for example in mines) of the present invention. Still other solutions provide for portions with cylindrical section adapted to be mutually coupled, but not suitable for the severe uses of the tool of the present invention, since their cylindrical shape does not provide them with a suitable hold in the coupling between the two portions during works.

Object of the present invention is solving the above prior art problems, by providing a percussion tool for demolishing hammer whose two portions are each made of an optimum material to support the stresses applied thereto during its use, and which are mutually connected in a highly reliable and long-lasting way.

This is obtained by providing that each portion is equipped with suitable connection ends shaped, in cross section, with an at least triangular shape, and preferably a quadrangular or generally polygonal shape, the portions are adapted to mutually make a coupling of the male-female type through these ends thereof, and finally are equipped with transverse holding means.

Due to this solution, each of the two portions of the tool is made of a material which allows optimally supporting the stresses applied during its use, and therefore the tool life will be highly increased. Due to the fact that the two portions are mutually connected, it is also possible upon need to replace a single one of the two portions, after having removed the holding means and withdrawn the portion to be replaced.

The above and other objects and advantages of the invention, as will appear from the following description, are obtained by a percussion tool for demolishing hammer as claimed in claim 1. Preferred embodiments and non-trivial variations of the present invention are the subject matter of the dependent claims.

It is intended that all enclosed claims are an integral part of the present description.

The present invention will be better described by some preferred embodiments thereof, provided as a non-limiting example, with reference to the enclosed drawings, in which:

- Figure 1 is a cross-sectional view of an embodiment of the tool according to the present invention, which shows the operating coupling between the two portions, shaft and cusp;

- Figure 2 is a view similar to Figure 1, which frontally shows the female coupling seat of the cusp;

- Figure 3 is a side view of the portion of Figure 2, which shows the working shape as chisel, or alternatively as bit, plated or with any useful outline;

- Figure 4 is a view similar to Figure 1, which shows the shaft in the male supporting portion of the tool of the invention; and

- Figure 5 is a front view of a portion of Figure

4.

With reference to the Figures, a preferred embodiment of the percussion tool for demolishing hammer of the present invention is shown and described. It will be immediately obvious that numerous variations and modifications (for example related to shape, sizes, arrangements and parts with equivalent functionality) could be made to what is described, without departing from the scope of the invention, as appears from the enclosed claims .

The percussion tool 1 for demolishing hammer (for example with pneumatic or hydraulic drive, not shown) for perforations, demolitions or excavations of the present invention comprises an elongated body, generally of a cylindrical shape, typically with circular cross section, and having:

a first portion 3 aimed to be housed at least partly inside, and connected with the demolishing hammer and made of a first material, since it is subjected to impacts applied to a beating mass of a known type, moving inside the hammer body. The first portion 3, in a per se known way, comprises a pair of diametrically opposite, plane elements 4, to allow retaining the tool 1 inside the hammer; and

a second portion 5, opposite to the first portion 3, which includes a working end 7; such second portion 5 is made of a second material which is different from the first material . According to the invention, such tool 1 is made so that :

* the first and the second portion 3, 5 are adapted to mutually make a coupling of the male- female type,

* each one of the first and the second portion 3, 5 is shaped, in its respective end 9, 11 adapted to make such male-female coupling, as a cross section whose shape is at least triangular, and

* the tool 1 is equipped with transverse holding means 14 for the first and the second portion 3, 5.

In order to best obtain the mutual holding against their relative rotation, during their operation, the cross section of the two coupling ends 9, 11 is preferably of a quadrangular shape, but obviously the shape could also be pentagonal or hexagonal or, in general, polygonal wih a number of sides and angles at will, according to the applications .

The male-female coupling between the two portions 3, 5 can be indifferently made: namely, the first portion 3 can be equipped with a coupling end 9 of the male type, adapted to be inserted into a corresponding coupling end 11 of the female type with which the second portion (as shown in Figure 1) is equipped. Or, the portion 3 can be equipped with a coupling end of the female type (not shown) , adapted to be inserted into a corresponding coupling end of the male type (not shown) with which the second portion 5 is equipped.

In particular, but not in a limiting way, the transverse holding means 14 can be composed of at least one peg 14 adapted to be inserted into corresponding recesses 16, 18 with which the first and the second portion 3, 5 are equipped, in order to mutually fasten such first and second portion 3, 5, unmovably in the longitudinal direction, after that they have been mutually coupled.

Still in particular, to obtain the best operation required by the application for which the percussion tool 1 of the invention is provided, the first portion 3 is made of a metallic material having high flexure resistance characteristics, and the second portion 5 is made of a metallic material having high hardness and hot wear resistance characteristics .

As possible constructive embodiment, the first portion 3 can be made of chromium-molybdenum or chromium-manganese alloyed steel, and the second portion 5 can be made of a tungsten and cobalt alloyed steel.

Alternatively, the same steel could be used both for the first portion 3, and for the second portion 5, subjecting the same steel to different heat treatments.

Claims

1. Percussion tool (1) for demolishing hammer for perforations, demolitions or excavations, comprising an elongated body having:

- a first portion (3) aimed to be connected with said demolishing hammer and made of a first material; and

a second portion (5), opposite to said first portion (3), which includes a working end (7), said second portion (5) being made of a second material which is different from said first material as regards type or property, characterized in that:

* each of said first and second portions (3, 5) is shaped, in its respective elongated end (9, 11) adapted to make said male-female coupling, with a cross section having at least a triangular shape,

* said first and second portions (3, 5) are adapted to mutually make a coupling of the male- female type exclusively through the elongated ends (9, 11), and

* said tool (1) is equipped with transverse holding means (14) for said first and second portion (3, 5) .

2. Percussion tool (1) according to claim 1, characterized in that said cross section is of a quadrangular or pentagonal or hexagonal or, in general, polygonal shape.

Percussion tool (1) according to claim 1 or 2, characterized in that said first portion (3) is equipped with a coupling end (9) of the male type, adapted to be inserted into a corresponding coupling end (11) of the female type with which said second portion (5) is equipped.

Percussion tool (1) according to claim 1 or 2, characterized in that said first portion (3) is equipped with a coupling end of the female type, adapted to be inserted into a corresponding coupling end of the male type with which said second portion (5) is equipped.

Percussion tool (1) according to any one of the previous claims, characterized in that said transverse holding means (14) are composed of at least one peg (14) adapted to be inserted into corresponding recesses (16, 18) with which said first and second portion (3, 5) are equipped, in order to mutually fasten said first and second portion (3, 5) , unmovably in the longitudinal direction, after that said first and second portion (3, 5) have been mutually coupled.

Percussion tool (1) according to any one of the previous claims, characterized in that said first portion (3) is made of a metallic material having high flexure resistance characteristics, and said second portion (5) is made of a metallic material having high hardness and hot wear resistance characteristics.

Percussion tool (1) according to claim 6, characterized in that said first portion (3) is made of chromium-molybdenum or chromium- manganese alloyed steel, said second portion (5) being made of tungsten and cobalt alloyed steel.

Percussion tool (1) according to claim 6, characterized in that said first portion (3) and said second portion (5) are made of a same steel subjected to different heat treatments in a portion with respect to another.

Percussion tool (1) according to any one of the previous claims, characterized in that, since said first and second portions (3, 5) are mutually connected, tbey are adapted to be replaced independently one from the other, after having removed the holding means (14) and withdrawn the portion to be replaced.