Tool driving or impacting – Impacting devices – Impact transmitting anvil
Reexamination Certificate
1998-11-13
2001-12-11
Smith, Scott A. (Department: 3721)
Tool driving or impacting
Impacting devices
Impact transmitting anvil
C173S133000, C173S210000, C173S135000
Reexamination Certificate
active
06328116
ABSTRACT:
The invention relates to an arrangement in connection with a hydraulic breaking apparatus comprising a tool, the arrangement comprising a housing placed around a percussion hammer.
Hydraulic breaking apparatuses, such as percussion hammers, are generally used to break relatively hard materials, for example stone, concrete, asphalt, frozen soil, metal slag etc. Percussion hammers are usually installed as auxiliary equipment in excavators instead of buckets, and they are usually operated by the hydraulics of the base machine. Other base machines and carriers can also be used. During breaking, dust and other impurities spread from the material to be broken to the surroundings, causing thus problems in the operation and durability of the breaking apparatus. Breaking apparatuses are also used and stored in demanding conditions. Therefore, in order to block the access of dust and other impurities to the structures of the breaking apparatus, the apparatus is usually enclosed within a housing. The housing also protects the percussion apparatus against external blows and weather conditions. Further, noise and vibration are diminished substantially when the percussion hammer is placed inside a housing and also supported thereto by means of damping elements.
However, there have been problems with the present breaking apparatuses as regards the durability of the housings. The lower ends of the housings are continuously subject to damages since during the breaking the tool of the breaking apparatus is pressed against the object to be broken and when the object yields and breaks under the tool, the breaking apparatus moves suddenly towards the object to be broken due to a feed force. In such a case, the lower end of the housing often collides with the surface to be broken. In time the lower end of the housing will no longer withstand this, but it will be damaged. There will be fractures and cracks in the housing, and impurities can have access to the broken housing through these openings, causing damage to the percussion apparatus. It is also possible that the housing is damaged to such an extent that the operation of the breaking apparatus will be prevented completely. Sometimes the operator of the breaking apparatus also uses the apparatus to move broken rocks and the like away from the place of breaking, which means that the lower part of the housing will also be subjected to blows. Consequently, the lower part of the housing is subjected to rather great stresses during the use of the apparatus. Therefore, it is necessary to repair the housings at times by straightening and welding. However, this produces additional costs and the breaking apparatus is out of productive use for long periods of time. On the other hand, it is not necessarily reasonable to manufacture the housing from a stronger sheet or to massively reinforce it in some other manner, since in such a case the breaking apparatus will be heavier and bigger and therefore more difficult to handle. Even though the material thickness were increased, the structure would still contain welded seams, joints and other points that are crucial for breakage.
The purpose of the present invention is to prevent the prior art drawbacks and to provide better protection for the lower end of a hydraulic breaking apparatus than previously.
The arrangement according to the invention is characterized in that the lower part of the housing is provided with a changeable wearing element receiving blows and forces directed at the lower part of the housing and forming the lower part of the housing, the tool being conducted through said wearing element.
The basic idea of the invention is that the lower end of the housing in a hydraulic breaking apparatus is provided with a separate wearing element that can be changed easily and that receives blows and forces directed at the lower part of the housing. Further, the wearing element forms the lower end of the housing and therefore the tool is conducted through the wearing element. The basic idea of an embodiment of the invention is that the wearing element is provided with a suitable protruding section or some other part that can be utilized in the breaking. Moreover, the basic idea of a second embodiment of the invention is that the wearing element locks the lower frame of the percussion hammer inside the housing.
The invention has the advantage that due to the wearing element the housing requires substantially less repairs. Also, changing the wearing element takes only a fraction of the time required previously by the straightening and repair welding of the housing. A changeable wearing element can be changed rapidly and the changing does not require special skills or tools. Therefore it can be changed even on the construction site, which means that the breaking apparatus will be out of use for as little time as possible due to maintenance. Another advantage is that the breaking apparatus can be provided, if required, with a wearing element that is manufactured for a specific use. For example a wearing element that is provided with a stone claw facilitating the removal of rocks and the like makes the breaking faster and easier when cumbersome rocks can be moved out of the way and the tool of the breaking apparatus can be directed at exactly the correct point on the surface to be broken. Further, the durability of the entire breaking apparatus is improved when there will no longer be any small cracks in the welded seams and joints of the housing through which impurities could have access to the housing to damage the seals and structures. Such a hidden flow of impurities to the percussion hammer that the operator is unaware of and that takes place over long periods of time can now be prevented. Another advantage is that the sealing of the tool of the breaking apparatus is realized in the changeable wearing element, which means that the seal that is subjected the most to dust and other impurities and that therefore also wears out most rapidly is changed at the same time as the wearing element. Further, the advantage of another embodiment of the invention is that during the maintenance of the breaking apparatus the wearing element can be detached rapidly from its fastening to provide fast access to the lower frame of the percussion hammer. After the wearing element has been detached, the lower part of the percussion hammer can be removed and repaired without disassembling the upper part of the percussion hammer. Also, the wearing element according to the invention does not hinder the use of the apparatus in any way nor does it complicate changing of the tool, for example, and it can be used in connection with most breaking apparatuses.
REFERENCES:
patent: 2094184 (1937-09-01), Noble
patent: 2936743 (1960-05-01), Colgate
patent: 5060734 (1991-10-01), Anderson et al.
patent: 5431235 (1995-07-01), Drumheller et al.
patent: 5878823 (1999-03-01), Henriksson
patent: 5896934 (1999-04-01), Yaniero et al.
patent: 0 144 282 (1985-06-01), None
patent: 952935 (1996-12-01), None
patent: 2 171 948 (1986-09-01), None
Hurskainen Arvo
Sippus Timo
Sandvik Tamrock Oy
Smith Scott A.
Smith-Hill and Bedell
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