Manually operable drilling tool with dual impacting function

Details Manually operable drilling tool with dual impacting function Manually operable drilling tool with dual impacting function

1999-07-21

2001-03-06

Vo, Peter (Department: 3721)

Tool driving or impacting

Drive adjustable to completely change kind of drive

Adjustable to impacting device

C173S109000, C173S201000

Reexamination Certificate

active

06196330

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to a manually operable drilling tool with a striking mechanism for producing axial impacts. The drilling tool includes a housing with a chuck fitted on the housing for rotating a tool bit secured in the chuck. The striking mechanism periodically transfers axial impacts to the tool bit
BACKGROUND INFORMATION AND PRIOR ART
In fastening and excavating technology, manually operable drilling tools are known, which have a driving mechanism for imparting rotary motion to a drilling tool and are equipped with a striking mechanism for producing pulse-like impacts. The axial impacts support the excavating action of the drilling tool, especially when drilling in brittle, failing material, such as concrete, rock, brick masonry and the like. For working on very hard and compact materials, such as concrete and rock, manually operable drilling tools, equipped with an electro-pneumatic striking mechanism, prove to be very appropriate, such handheld or manually operable drilling equipment has long been known and is sold, for example, by the Assignee. The electro-pneumatic striking mechanism of such drilling equipment is designed for producing axial impacts with a high individual impact energy of, for example, about 2 J to about 8 J at a relatively low impact frequency of, for example, about 45 Hz to about 80 Hz. Because of the high energy of the individual axial impacts, manually operable drilling tools are not as suitable for working hollow brick masonry.
Aside from the manually operable drilling tools with an electro-pneumatic striking mechanism, other drilling tools are also known, which have a mechanical striking mechanism. These include the ratchet drills, known primarily for home owner use and the manually operable drills with a spring U-bolt striking mechanism or a spring-cam stroking mechanism employed in semi-professional and professional use. The striking mechanisms of these known handheld drilling tools produce axial impacts with a relatively low single impact energy of, for example, about 0.03 J to about 0.3 J with a relatively high impact frequency, which amounts to about 700 Hz., for example. Because of the low energy of the individual impacts, it is possible to work with impact support on hollow brick masonry with such manually operable drilling tools without destroying the hollow bricks. For working on hard materials, such as concrete or rock, such drilling tools with a mechanical striking mechanism find less use. Because of the low energy of the individual axial impacts, the user of the drilling tool must press relatively strongly against the material and the achievable drilling progress generally is too little for the professional user.
For working different materials, such as concrete and hollow brick masonry, two or more axial impact-supported manually operable drilling tools are required, the axial impacts of which have the single impact energy and impact frequency, suitable for the respective material, in order to work it with sufficient drilling progress, without at the same time damaging it. In general, buildings are not constructed of a continuously homogenous building material. For example, buildings have concrete load-bearing parts and the sections between these parts frequently consist of brick masonry, especially hollow brick masonry. The tool operator, who is to produce boreholes, openings or the like in these different materials in the past always had to use at least two handheld drilling tools with different stroking mechanisms having different impact energies. Since he cannot be expected to carry along two or more manually operable drilling tools at all times, the procurement of the tool, suitable for the respective material, leads to undesirable delays.
OBJECT OF THE INVENTION
Therefore, it is a primary object of the present invention to provide a remedy for these disadvantages in the state of the art. The tool operator is placed in a position to work the material, without any great delay, using the same drilling tool and working point suitable for such purpose.
SUMMARY OF THE INVENTION
This objective is accomplished in a manually operable drilling tool with a first and a second striking mechanism each arranged to transfer axial impacts to the drilling bit where the axial impacts of each have a different impact energy and impact frequency, with means for operating the striking mechanism, individually, in tandem or for rotating the tool bit without any axial impact. The manually operable drilling tool is equipped with a first striking mechanism, disposed within a housing, for producing axial impacts, which can be transferred to a rotatable drilling or chiseling tool bit, clamped in a tool chuck of the drilling tool. Within the housing, a second striking mechanism is provided for producing axial impacts, which have an impact energy and an impact frequency, different from the impact energy and the impact frequency of the axial impacts produced by the first striking mechanism. The drilling or chiseling tool bit clamped in the chuck can be acted upon by axial impact from either the first or the second striking mechanism or in tandem by using both striking mechanisms together. For special applications, the axial impact mechanisms can be switched off completely.
The manually operable drilling tool of the present invention combines in one tool several drilling tools with striking mechanisms for different single impact energies and impact frequencies. Since such a manually operable drilling tool can be operated with the first striking mechanism providing axial impacts of high energy and low frequency or with the additional striking mechanism offering individual axial impacts of low energy and high frequency, or with both striking mechanisms operating together, the impact output can be adapted very easily to different materials. It is no longer necessary to provide several drilling tools with striking mechanisms for providing axial impacts with different individual impact energies and impact frequencies. The impact parameters of the striking mechanism of the manually operable drilling tool can be adapted at the work site for the materials to be worked. It is self-evident that such a drilling tool can be operated without axial impact support, since both stroking mechanisms can be switched off. This type of operation is desirable, for example, for drilling at a high rpm and without axial impact in wood and metal.
For flexibility in the use of the manually operable drilling tool on a large number of different solid materials, it is advantageous if the individual impact energies of the axial impacts produced by the first and second striking mechanisms have a ratio in the range of about 6: to about 250:1, and preferably in the range of about 10:1 to about 40:1, and if their impact frequencies have a ratio in a range of about 1:1.1 to about 1:15.
It has proven to be advantageous if the first striking mechanism is an electro-pneumatic striking mechanism with an exciter piston disposed within a guiding tube, a free piston and a snap element acting on the drilling or chiseling tool bit disposed forwardly in axial alignment with the guiding tube. Preferably, the second striking mechanism is a mechanical striking mechanism, which interacts with the snap element. The differences in the energies of the individual parts and in the impact frequencies of the striking mechanisms can be achieved, for example, because impacts are produced completely differently by electro-pneumatic and mechanical striking mechanisms.
The mechanical striking mechanism can be constructed as a single ratchet striking mechanism or as a spring U-bolt striking mechanism. From a structural point of view and in order to achieve satisfactory drilling progress in spite of the low impact power, a spring-cam striking mechanism has proven to be advantageous.
In order to cover the largest possible area of use for different, solid materials, it is advantageous if the electro-pneumatic striking mechanism for producing axial impacts is constructed with a large individual impac

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