DE102018007711A1 - Manufacturing process for deep drilling tools - Google Patents

Abstract

A manufacturing process for deep drilling tools is presented in three variants: from a simple cylindrical blank (hard metal, ceramic or materials of equivalent wear resistance) with blind holes already drilled on the end face (see Figure 1), or from a blank of the same dimension, in which the later ones are already sintered Chip spaces and discharge openings were milled (see Figure 3), or from an additively constructed blank with identical geometry from the beginning, whereby the latter can consist of the various cutting materials themselves or only of a tougher core for later wear-resistant and cutable coatings or applications. In contrast to the conventional machining or grinding of drilling heads with the usual one-sided ("flying") clamping, it is possible with these blanks to carry out the peripheral processing for two drilling heads in one clamping. The orientation at the blind holes (see Figure 2) ensures a later, seamless transition from the drill head to the inside of the drill pipe, and the head diameter and, above all, a very constant taper of the head guide can be produced faster and still more accurately, since workpieces clamped on both sides are very much able to withstand the machining pressure dodge less. Using this procedure, it is now possible to safely operate even smaller diameter ranges that were previously reserved for more sensitive and expensive solid carbide tools. But drilling tools manufactured in this way should also be quite attractive in the lower limit range that has already been reached.

Description

Technical part:

Deep drilling tools are preferably used in task-related machine tools for drilling holes, the drilling depth of which is predominantly much larger than the hole diameter. They are generally designed in such a way that a permanent coolant flow causes uninterrupted discharge of the drilling swarf, so that repeated application or expansion is not necessary. Deep drilling tools are mainly used in the metallic, but sometimes also in the non-metallic area.

Relevant state of the art:

Deep drilling tools have been known for a long time and are primarily named after the drilling processes for which they were designed. A distinction is made between the ELB process for drilling in the rather smaller diameter range, the BTA process for more powerful drilling and drilling operations and the ejector process for special chip return. Relevant for this patent application is the so-called BTA method, in which the drill head is connected to a round drill pipe with optimal torsional rigidity, but also has disadvantages compared to an ELB tool. B. with regard to the more complex production and the less regrinding, especially with small tool diameters, which do not yet allow the use of indexable inserts. For some time now, attempts have been made to move the BTA process more into the previous field of application of the ELB technology by means of modified drilling heads (with better guiding properties and often regrindable head geometry).

Task:

The invention is therefore based on the object to provide a method which, on the one hand, allows drilling tools to be produced with sufficient precision and economically, even for smaller drilling diameters than previously possible, but on the other hand can also use somewhat larger, previously practiced drilling tasks, the complement and not exclude positive properties from ELB and BTA technology.

Disclosure of the Invention:

This object is achieved by the features of claim 1 (main claim), according to which a manufacturing process is presented which compensates for the mechanical disadvantages of so-called "flying machining" by double-sided clamping with twice the output, and also by the new shape of the blanks in terms of Drill head guidance and regrindability is hardly inferior to classic ELB drill heads.

Examples:

• 1 shows in principle the process from the blank production to the common pre-processing of two drill heads, the lateral surfaces of which have already been ground before the separation. According to the drilling task, the blank ( 10th ) geometrically designed and, in the pre-sintered state, provided with the later return holes on the front. Please note the shrinkage during final sintering, because the diameter of the return holes must then coincide with the later pipe inside diameter. The finished sintered blank is picked up between the tips and ground to the nominal size on the outside diameter ( 11 ). Subsequently, in the same clamping on the left and right and according to the later drill head length, the lateral surface is slightly tapered according to deep drilling-specific experience ( 12th ). On the remaining cylindrical area ( 13 ) recorded in a collet ( 14 ) the cones for the connection to the drill pipe are then ground on the end of the workpiece one after the other ( 15 ). This machining can be carried out "on the fly", since these cones do not have the same requirements as the later drill head guidance, and due to the first machining between tips there is no significant offset to the interior of the drill pipe. Then the workpiece is separated in the middle area, and you get the two actual drill head blanks ( 16 ).
• 2nd shows the possible connections between the drill head and the drill pipe, whereby an intermediate adapter is preferred for as yet unknown drill pipe lengths or for stockpiling ( 20th - 22 ). The blank is taken up in a collet (on the outside diameter of the pipe) ( 16 ) now shortened to the desired length and partially ground down to the main cutting plane and until the opening in the inner bore ( 23 - 25th ). A slanted cut makes it possible to incorporate a larger inlet funnel for the chips that will later primarily arrive off-center ( 26 - 28) . The overall view of the operational deep drilling tool ( 29 ) only serves to show the simultaneous improvement in terms of head guidance and regrinding. Cutting geometry, guide chamfers and free grinding for the passage of the coolant have long been state of the art and are therefore not part of this patent application.
• 3rd shows a modified blank, how it could be built completely "additively" ( 30th ), as well as the possibility of mechanically incorporating these changes into the already known pre-sintered blank ( 10th ) to incorporate ( 31 - 33 ). The individual grinding operations are identical to those from 1 , also up to the provision of two identical drill head blanks ( 36 ).
• 4th shows that the further handling similar to that in 2nd is. As a result of the different contours of the modified blank, grinding of the main cutting plane and widening of the chip opening are omitted, which further reduces manufacturing costs. Here too, the operational deep drilling tool is shown in its entirety ( 49 ), but again only to clarify the improvement in terms of head guidance and regrinding. Cutting geometry, guide chamfers and free grinding for the passage of coolant are also state of the art in this head shape and are therefore also not part of this patent application.

Advantages of the invention:

A major advantage lies in the cost range, since the required accuracy with workpieces clamped on both sides can be achieved with fewer work steps than with one-sided clamping (with less bending rigidity). The fact that peripheral machining (lateral surfaces) is always possible for two drill heads in the same clamping increases the economy even more. Simpler drilling tools ( 29 / 2nd ) for good machining materials can also be made from a very simple blank ( 10th / 1 ) are manufactured, and for the more demanding machining of high-strength materials, which require more resilient and geometrically modified drill heads ( 49 / 4th ), all possibilities of contemporary "additive manufacturing technology" can even be fully integrated into this procedure. The desired improvement of the BTA drill heads in terms of guide length and regrinding can easily be met when designing the blank length. The end-side cones for connection to the drill pipe also make a significant contribution to the length of the blank, but allow the torsional strength of the drill pipe to be fully transferred to other weak points such as B. with a threaded connection. Ultimately, this manufacturing process also makes it possible above all to produce BTA tools for drilling diameters that are even smaller than before with the necessary precision.

Claims (4)

Manufacturing process for deep drilling tools, with the steps of introducing the blind holes on the end face into a pre-sintered, cylindrical blank made of hard metal, ceramic or adequate. (10 / 1 ), Finished sintering and picking up the blank between tips for grinding the outer surface = later drill head diameter (11 / 1 ), Grinding the subsequent deep drilling-specific conical zones (12 / 1 ), Holder on the cylindrical center (13 / 1 ) by means of a collet and grinding the ends of the blank = holding cones for the tool carrier (14 and 15 / 1 ), Cut in the middle to obtain two equivalent drill head blanks (16 / 1 ), Connecting (gluing, soldering, welding) the blanks with the drill pipe or with an adapter for later connection with pipes of unknown length (20 - 22 / 2nd ), Mounting on drill pipe or adapter, shortening to the desired drill head length and grinding the main cutting plane (23-25 / 2nd ), Widening the transition to the interior, e.g. B. using a grinding pin (26 - 28 / 2nd ). Claim to Claim 1 , characterized in that before the blank is sintered (10 / 3rd ) the chip spaces and the transitions to the interior are also milled in, whereby it should be noted that some machining allowance remains in the chip spaces for later sharpening up to the main cutting plane (31 - 33 / 3rd ). Claim to Claim 2 , characterized in that the blank (made of the materials mentioned at the outset) is completely built up to the final contour using contemporary additive manufacturing processes and sintered (30 / 3rd ). Claim to Claim 3 , characterized in that the blank as in Claim 3 , but only made of an impact-resistant core material, and the more wear-resistant zones and the cutting area can only be completed after pre-processing by means of coating, applications or inlays.

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