Boring or penetrating the earth – With above-ground means for handling drilling fluid or cutting
Reexamination Certificate
1999-03-17
2001-03-13
Pezzuto, Robert E. (Department: 3671)
Boring or penetrating the earth
With above-ground means for handling drilling fluid or cutting
Reexamination Certificate
active
06199644
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a drilling tool having a housing, a suction device, and at least one gas spring which cooperates with both the housing and the suction device and an operational direction of which coincides with a drilling direction.
2. Description of the Prior Art
During formation of bores in a constructional component formed of concrete, stone, steel and the like, a cooling medium for cooling the tool and for removing drillings is used. In order to keep the working location as clean as possible, usually suction devices formed as suction heads are used. The suction head surrounds the end, in the drilling direction, region of the drill and seals the working location from outside. The suction head has a suction nipple with which it is connected with an external vacuum-producing apparatus.
German Utility Model DE-GM 8813719 discloses a drilling tool with a suction device and including a gas spring having a cylinder and a piston rod, with the cylinder being secured to the housing of the drilling tool and the free end of the piston rod being connected to the suction device. The piston rod and a surrounding it, sealing region, because of their exposure, are subjected to contamination which results not only in a rapid wear of the sealing region and in damaging of the piston rod surface, but also in malfunction of the entire drilling tool.
Accordingly an object of the present invention is a drilling tool with a suction device in which important parts of the gas spring, which are connected with the suction device, are protected from contamination and have, therefore, a long service life, insuring a functional reliability of the entire drilling tool.
SUMMARY OF THE INVENTION
This and other objects of the present invention, which will become apparent hereinafter, are achieved by providing a drilling tool including a housing, a suction device, and at least one gas spring which cooperates with both the housing and the suction device and an operational direction of which is parallel to a drilling direction. The housing has an opening for receiving the piston rod and at least a section of the cylinder of the at least one gas spring.
The arrangement of the gas spring according to the present invention insures that its piston rod and the sealing region, which surrounds the piston rod and is associated with the cylinder, are completely protected from contamination. In order to prevent the pivotal movement of the suction device from its position, in which it is located coaxially with the drill, there is provided rotation-preventing means. This means can include, e.g., a strip arrange on the cylinder of the gas spring and an elongate groove provided in the housing for receiving the strip.
To provide for a reliable support of the gas spring and a reliable guidance of the suction device, the spring cylinder cooperates with the suction device, and the piston rod extend into bore formed in the housing and is supported against a stop surface provided in the housing bore and facing in the drilling direction.
To provide for a large displacement path of the suction device, which is larger than the most possible stroke of the gas spring, advantageously a second gas spring is provided, which is arranged in tandem with the first spring, with the second spring being connected with the suction device, and with both springs being connected with each other by a connection element.
In order to protect the piston rod of the second spring from contamination, advantageously, the second gas spring is arranged in a receiving sleeve-like member, which projects from the connection element in a direction opposite the drilling direction and which is at least partially received in a second bore provided in the housing.
In order to prevent rotation of the second gas spring relative to the receiving sleeve, which is fixedly connected with the connection element, rotation-preventing means is provided between the second gas spring and the receiving sleeve.
In order to insure a good support of the second spring and a reliable guidance of the suction device, advantageously, the cylinder of the second gas spring is connected with the suction device, and the piston rod of the second gas spring is supported against a stop surface provided in the receiving sleeve and facing in the drilling direction.
In order to be able to insert a drill into the drilling tool, the length of which substantially corresponds to the stoke of the gas spring, it is necessary to inserethat only the second gas spring can be drawn out, with the first gas spring remaining in its drawn-in preloaded condition and located in the first receiving bore formed in the housing. This is preferably achieved by formlockingly connecting the connection element with the housing. For a reliable and easy handling, the formlocking connection of the connection element with the housing is formed by a stop rim associated with the housing and facing in a direction opposite to the drilling direction and a locking element, displaceable perpendicular to the drilling direction.
In order to be able to place the inventive drilling tool in a transportation box, it is necessary that not only the first gas spring but also the second gas spring can be retained n the drawn-in, preloaded position. Advantageously, this is achieved by providing in a second gas spring a locking region facing in the drilling direction and in which the locking element is formlockingly engaged in the drawn-in, compressed position of the second gas spring.
REFERENCES:
patent: 4440450 (1984-04-01), Coakley
patent: 4709462 (1987-12-01), Perkin et al.
patent: 4765417 (1988-08-01), Perkin et al.
patent: 4776410 (1988-10-01), Perkin et al.
Niedermann Peter
Roth Peter
Thanner Thomas
Brown & Wood LLP
Hilti Aktiengesellschaft
Pezzuto Robert E.
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