Method and Apparatus for the Production of Machine Tools

This invention relates to machine tools and more particularly to the method and apparatus for producing spiral type drills with interior cooling channels.

Three separate processes have been developed according to the latest status of technology for the manufacture of twist drills with inside cooling channels. The most commonly used consists of machining a blank with bores corresponding to the necessary cooling channels and then finishing subject blank by milling or rolling operations.

The second process deviates from above only in that the blank has two indentations grooves each other either by means of forging or by means of rolling, prior to machining the channels. Further work on the blank is identical to the above, i.e., milling or rolling operations.

The newest development to provide for inside cooling channels consists of an extrusion operation. In spite of the fact that the drill will be formed with inside cooling channels in a single operational step, this method contains certain difficulties. For example -- to avoid closing of the channels. In this regard, a certain filling substance is used (for example copper) when forming is concluded which must be melted out. Technical disadvantages of this process further lie in the fact that the core thickness along the spiral of the drill remains constant. It is not solved at this time on how to decrease the thickness of the drill core along its axis. Further, due to difficulties connected with the melting of the filling material, the production of smaller drills remains impossible, i.e., under 10 mm diameter.

One should mention here attempts to product drills containing inside channels by roll forging. Trials were conducted according to an extrusion operation to fill the blank with a filling material, for example copper wire, with subsequent rolling on a roll forging machine. It became known that the blank, when roll forged, is subject to a reduction in area (approximately 50%) due to a rotational movement. Thus, the inside channels migrated periodically in the drill core and became closed in spite of the inlay.

As a countermeasure, theoretically one could deform the blank prior to the rolling process in a direction opposite to the spirals. This would make the process of extrusion and its problems applicable to roll forging.

In order to eliminate the above difficulties which prohibited the production of drills with inside cooling channels on a large scale, the subsequent process was developed which permits production of twist drills by roll forging, incorporating inside cooling channels without the usage of a foreign filling substance.

The invention consists of producing drills or alike with inside cooling channels by means of core matrix or core pins incorporated in the forming pass by roll forging or extruding in a single operational step.

To use the process for drills above 2 mm diameter, one can make use of a steel tube commercially available or a concentrically bored work blank. For bigger dimensions, for example above 5 mm diameter, a round work blank can be used with pre-bored channels.

Using the invention for drills with a diameter above 30 mm, it would be recommended to divide the rolling process into two operational steps subsequent to each other with the first step as a straight rolling operation. The second step can then consist of a roll forging or other forming process. The core matrix, or respectively the core pins with the roll pass, which are primarily used in the first step can, when producing drills above 30 mm diameter, also be used in the second forming step.

In view of the above, it is an object of the present invention to provide an improved process for producing twist type drills having interior channels therein.

Another object of the present invention is to provide an improved apparatus for producing twist type drills having interior channels therein.

An even further object of the present invention is to provide an improved means and method for producing twist type drills having cooling channels formed therein.

Other objects and advantages of the present invention will become apparent and obvious from a study of the following description and the accompanying drawings which are merely illustrative of such invention.

FIG. 1 is a sectional view of the rolling tools and the laid-in core matrix of the present invention;

FIG. 2 is a sectional view of the product being produced into a rolled twist drill;

FIG. 3 is an axial sectional view of a twist drill over 5 mm diameter;

FIG. 4 is a sectional view of the product produced;

FIG. 5 is a sectional view of a variation of the product produced;

FIG. 6 is a schematic view of a forging means that can be used with the present invention;

FIG. 7 is a schematic view of a variation of the means of FIG. 6;

FIG. 8 is a sectional view of a variation of the present invention;

FIG. 9 is a longitudinal sectional view of the core matrix for a known extrusion pressing operation;

FIG. 10 is the core matrix as viewed from the tip of the core pins; and

FIG. 11 is a sectional view of the ring caliber with in-laid core matrix.

We will now discuss the process to produce machine tools, i.e., drills or alike with inside cooling channels by means of roll forging or extruding press in more detail on the basis of FIGS. 1 - 11:

FIG. 1 shows a section of the roll pass 1 in plane 4--4 of the rolling tools 7a, 7b, 7c and 7d, with the laid-in core matrix 2, respectively core pins 3 and 3a, which in this form 10 are of flat shape and which are fixed at the point of the forming plane 4--4. The blank R, in a known fashion, will be transported from a storage compartment into the heating coil H. With the blank having reached the deforming temperature, the core matrix or respectively the core pins 3, 3a, will be pushed into the hot blank which will then be moved by means of the pusher 5, 5a, into the opening of the roll pass 1 and fixed in rolling plane 4--4. Meanwhile, the pusher 5, 5a, continues its axial movement in direction 6, 6a to the roll pass so that the now rolled work blank W will be pushed away from core matrix 2 or respectively core pins 3, 3a and then ejected, as known, now as a deformed drill with inside open channels. A new work blank R will be pushed into the heating coil H and a new operational step starts.

FIG. 2 shows a section of Item W, for instance, twist drills with inside cooling channels 9. The work blank R can consist of a commercially available steel tube or a round, concentrically bored shape 2A. The core matrix 2 can originate from a cylindrical round shape and develops into 2 profiles -- 8, 9, 10, corresponding to the eventual cooling channels. The tip 12 of the core matrix 2 of cone shape 23, is fixed to the forming plane 4--4 of the roll pass 1. Thus, product W will be ejected as a rolled twist drill in known fashion.

The core of the spiral drill originating from a tube shaped starting material consists of 2 parts 25, pressed together, welded to each other due to the high temperature and extremely high deformation pressure. It might be recommended to coat bore 2a of the work blank with a medium conducive to welding, when processing special steel grades.

The form and section of the channels depends on the form and section of the core matrix 2, respectively core pins 3 located in the forming plane 4--4. By virtue of the cone shape 23, it is possible to vary the form and section of the channels. The opening of the channels can be governed by the axial movement 13, 13a of core matrix 2 or core pins 3. The axial movement of core matrix 2 respectively core pins 3, can be connected with the movement of the work blank, permitting a proportional reduction in area of the channels 8 and 9.

We define as the forming plane or rolling plane 4--4 the location of the roll pass 1 where the axis 24--24 of the roll tools 7a, 7b, 7c, 7d cross the axis of the product W. The roll pass at this position consists of its smallest section and the rolling of the product is completed. The changes in sections of the channels in FIGS. 1 and 4 is indicated as Item 15.

FIG. 3 shows an axial section for twist drills over 5 mm diameter. The work blank R will be provided with 2 or several bores 3a in known fashion. Having reached the deformation temperature, core pins 3 will be pushed in at which time the blank will be transported to the opening of roll pass 1. In the meantime, roll tools 7a, 7b, 7c, 7d will move in direction 14 and the deforming process begins.

The core pins 3, which hereby mean the core matrix of the roll caliber, 1, will be fixed to the deforming plane 4--4. The formed product W will thus be removed from it and ejected in known manner.

Subsequently a new work blank R will be pushed into heating coil H (FIGS. 6 and 7) and a new working period starts.

FIG. 4 shows a section of product W which was processed from the tube shaped original material as shown in FIG. 2. The 2 parts of the bore core welded together is shown in Item 25. The possible reduction in area 15 of the channels 9 is also shown.

FIG. 5 shows as a further variation of the invention the cooling channels 8 and 9 in drop shapes.

FIG. 6 shows the schematic roll forging process, for example in accordance with U.S. Pat. No. 3,031,553, which can be used together with the above described invention for the production of twist drills with inside cooling channels 8 and 9.

FIG. 7 as a further variation of the invention shows the application as a pre-rolling phase of a known roll forging device. The roll pass 1 is hereby shown as a straight rolling device and equipped with the disclosed core matrix 2 respectively core pins 3 as shown in FIGS. 1-5. These variations of the invention will be used for example in making bigger twist drills, i.e., above 30 mm diameter.

FIG. 8 shows a longitudinal section of a further variation of the invention in connection with known extrusion pressing. The forming pass here consists of a closed ring 19 which can be used by the introduction of core matrix 2 for the production of twist drills and alike with inside cooling channels.

The core matrix 2, as disclosed in FIG. 2, is shown as a cone formed pin 23 corresponding to channels 21, the tip 12 of which is moved towards the deforming plane 20--20 of ring pass 19 and fixed thereon. The ring pass 19 which is designed for the production of twist drills can now be used by the introduction of core matrix 2 for the production of twist drills with inside cooling channels.

FIG. 9 shows a longitudinal section of the invention of core matrix 2 for a known extrusion pressing operation. The channel forming nose 23 of core matrix 2 is cone shaped and inclined by angle 16 towards the channel spiral. The form and section of the channels as per cone 23 or nose 12 located in the deforming plane 20--20 result in a variation of the section and shape of channels 21 by axial movement 13 of the core matrix 2.

It may be required with larger dimensions to re-cool the core matrix. In order to re-cool the core matrix, a bore 17 is provided together with tube 18 for the cooling medium.

FIG. 10 shows core matrix 2 as viewed from the tip of the core pins 12.

FIG. 11 shows the section of the ring caliber 19 with in-laid core matrix 2 in the deforming plane 20--20.

With the known roll forging process of twist drills or alike, the rolling process proceeds from the shaft to the drill tip. Contrary, with extrusion pressing the direction is reversed, i.e., from drill tip to shaft. Therefore, it is recommended in case of bigger drills equipped with cone shafts to attach the shaft portion making use of a less expensive material subsequently, i.e., by welding.

By using core matrix 2 or core pins, channels 8, 9 and 21 of the product remain open so that one eliminates to fill the holes of the work blank prior to its forming process with a previously known copper which later needs to be melted out again. The production of inside channel drills with extrusion pressing has only been possible in bigger dimensions due to the uncontrollability of the form and section of the channels using metal fillings.

From the above, it is obvious that the present invention has the advantage of providing a spiral type drill having interior cooling channels which is less expensive to produce and yet is superior in quality to prior known means.

The present invention may, of course, be carried out in other specific ways than those herein set forth without departing from the spirit and essential characteristics of the invention. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.