SE446953B - BORRUNDERLEGG - Google Patents

Description

15 20 25 30 35 446 953 2 foils, has the task of reducing the tendency of the wood fiber board to bend, and in addition, metal foils have been shown to have a cooling and cleaning effect on the drill bit.

The object of the invention is to provide a drilling mat which allows efficient suction of dust and particles not only from the inlet sides of the boreholes, ie from the upper side, which is relatively light, but also from the underside, ie through the outlet side of the boreholes.

Another important object of the invention is to provide a drilling mat which is inexpensive and facilitates suction of dust and particles and enables efficient air cooling of the drilling tools.

These objects have now been achieved in that the drilling mat according to the invention has obtained the features stated in claim 1 and possibly the improvements specified in claims 2 and 3.

A further object of the invention is to provide an efficient way of cooling the drilling tool and cleaning the drill holes, and this object has been achieved by the method defined in claim 4.

The invention is described in more detail below with reference to the accompanying drawings, in which Fig. 1 schematically shows a drill with a presser foot, a work table and a drilling mat according to the invention between sheets or laminates with printed circuits to be drilled, Fig. 2 is a similar view as Fig. 1 but showing the drilling mat in a section perpendicular to Fig. 1, i.e. along the corrugated pipes, and Fig. 3 shows on a larger scale a section of the drilling mat according to the invention.

Fig. 1 shows a part of a drilling machine with a work table 1, a presser foot 2 and a drilling tool 3 for drilling a number of sheets or discs 4 with printed * electrical circuits, for example copper circuits on glass fiber laminate. The sheets or discs 4 are placed on according to the invention, which drill is placed on the work table 1. As a drilling pad S, in turn, a drilling overlay over the sheets or discs 4 is placed on a thin sheet 6. consisting of metal foil, preferably aluminum foil, or for example a sheet of phenolic resin-impregnated paper or other suitable drill overlay material. This stack consisting of sheets or discs 4 with printed circuits, the drill pad 5 and the drill overlay sheet 6 are held together at the work table 1 in a conventional manner by means of a number of stacking pins 7, which extend through holes in the stack of sheets and drilling mats and into holes in the work table 1. For drilling, the presser foot 2 is applied to the stack. f J The presser foot 2 has the shape of a housing, which surrounds the drilling tool 3 (or any drilling tool) and is connected through an opening 8 and a pipe 9 to a suction source (not shown) for suction of particles and dust.

According to the invention, a laminate 5 is used as drilling mat, which consists of or comprises a corrugated board, which in the embodiment shown is in the form of corrugated cardboard, the corrugated pipes 10 forming channels for air flow in the drilling mat and extraction of dust and particles through the borehole and via presses. foot 2 to the vacuum cleaner, as soon as the tip of the drilling tool 3 penetrates the upper planar layer ll of the corrugated cardboard.

The air flow from the corrugated pipes 10 through the borehole is started immediately, when the drilling tool 3 punctures the planar layer 11, and the air flow upwards, for example a spiral flow along the spiral drilling tool 3, effectively cleans both the drilling tool and the borehole edges. to effectively cool the drilling tool immediately after a drilling operation and during the extraction of the drilling tool, whereby during the extraction of the tool dust and particles detached from the material and the drilling tool are effectively sucked away.

The drilling mat 5 according to the invention also has that advantage. that at the desired low amount of material and weight it has a relatively large thickness and provides the desired distance between the material 4 to be drilled and the work table 1.

Particles which are not sucked upwards and out of the housing 2, when the drill bit has penetrated the upper plane layer 11 of the corrugated board, are not enclosed, unlike the relationship with previously known drill pads in the borehole itself, from which it can penetrate between the sheets 4 and the drill pad, but can fall freely down into the relatively large, empty spaces formed by the corrugated pipes 10.

It can be seen from Fig. 1 that the corrugated pipes 10 above the corrugated paper 12 or below the corrugated paper comb serve as air flow channels depending on the area in which the drill bit penetrates the corrugated board.

Fig. 2 illustrates the air flow when the drilling tool just leaves the material when pulled out. However, depending on the type of drilling tool used, a greater or lesser degree of suction through the borehole may occur as soon as the upper planar layer of the corrugated board is perforated by the drilling tool.

Fig. 3 shows a drilling mat 5 according to the invention, which consists of a corrugated board of the single corrugated board type, on the upper planar layer 11 of which a layer 13 of hard paper or metal foil is applied, such as aluminum foil, which layer can be glued on corrugated cardboard upper upper layer ll. A layer of metal foil, such as aluminum foil, improves the cooling effect on the drill bit itself by heat dissipation, but because the air flow from the corrugated pipes through the borehole has a good cooling effect, in many cases the additional cooling effect can be dispensed with by aluminum foil. Drilling mats according to the invention consisting of one-sided corrugated cardboard and two-corrugated cardboard have been found to be used with satisfactory results, but single-corrugated cardboard, which has two opposite planar layers 11, 14 (and possibly an extra outer layer 13 of eg aluminum foil or other material suitable for reinforcement or drill bit cooling). preferred in that it provides relatively even abutment against the work table and offers even abutment of the stack of circuit or printed circuit boards or sheets 4 and overlay sheets 6. In comparison with two-wave cardboard, single-wave cardboard is cheaper but has like two-wave cardboard the advantage of allowing air suction into the boreholes from clean corrugated pipes 10 regardless of where a drilling tool tip penetrates the upper planar layer 11.

In the above there has been talk of printed electrical circuits, circuit boards, etc., but of course the drilling mat according to the invention is useful in drilling other material, in which the problems are equivalent to the problems of drilling in sheets of printed electrical circuits, and especially when it is It is important that the drilling tools are efficiently cooled by air flow. Furthermore, it should be noted that it is possible to achieve some of the objects of the invention also with material other than conventional corrugated board for forming channels, which are functionally equivalent to the channels 10. However, corrugated board of any commercially manufactured type is preferred if not otherwise for cost reasons,

Claims (2)

10,446,953 PATENT CLAIMS Disc-shaped drilling mat consisting of a laminate and intended to support disc-shaped or other 'flat material in relation to a work table (1) or the like during drilling through the material by means of drilling tools (3), characterized in that the drilling mat laminate consists of a corrugated layer (12) of paper and at least one planar layer (11, 14) of paper adhered to the corrugation tops on one side or both sides of the corrugated paper layer. Drilling underlay according to claim 1, characterized in that an additional reinforcing planar layer (13) is attached to the outer side of one planar layer (II).