RU2413596C1 - Method of machining deep through bores - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: proposed method comprises drilling with feeding lubricant-coolant into gap between drilling surface and toll that includes stem and drilling head, and controlling ship by lubricant-coolant flow via inner bore of stem and head. Bores are subjected to finishing at certain drilling conditions and tolerable wear in one cycle of tool use. Note here that chip control in reaming is performed via drilled bore in forward reaming feed direction, while lubricant-coolant feed is performed at no less than 40 atm in amount that ensures stable fluid flow in direction of tool feed.

EFFECT: higher quality of machining after withdrawing drilling head.

2 dwg

Description

The invention relates to the field of metal cutting, in particular to methods for processing deep holes with a processing depth of more than 5d, where d is the diameter of the processing.

A known method of processing deep through holes, including pre-drilling, replacing the drill with a reamer, followed by final deployment with coolant removal with chips through the gap between the tool and the wall of the machined hole (see RF patent No. 2156180 of 09/20/2000), adopted as a prototype .

The disadvantage of this method is that, when deployed, the chips can penetrate into the gap between the tool and the wall of the hole in the direction of the feed direction, compress in this gap and damage the already machined surface of the hole. In addition, when replacing the drill with a reamer, it is possible to offset the axis of the tools, which will lead to a distortion in the shape of the hole.

A method for processing deep through holes is proposed, including the supply of coolant under a pressure of at least 40 atm (400 MPa) into the gap between the surface to be machined and the tool. The stalk of the tool is permanently fixed in the spindle of the machine and a drill head or reamer is alternately installed in it. When drilling, chip evacuation is performed by the coolant flow through the internal channel of the drill and the stem.

When machining holes, the greatest risk of surface damage is the ingress of chips into the gap between the tool and the surface to be machined, especially during final processing. The coaxiality of the installation of the drill head and reamer during the transition from one operation (drilling) to another (deployment) plays a large role in this.

When finishing a hole under certain cutting conditions and the allowable amount of wear per installation, using the same stem, the drilling head is replaced by a reamer. The coolant is supplied under the same pressure, and the amount of fluid is such that it flows continuously in the direction of supply of the tool. Thus, the chips do not fall into the gap between the tool and the already machined surface of the hole, which is not damaged.

To explain the described method, figure 1 shows a stem with a drilling head; figure 2 - stem with a scan.

To implement the method of processing deep through holes on the stem 1, mounted in the spindle of the machine, a chamber 2 is installed, the joint between them is sealed with rubber rings 3. On the stem 1 is attached a drilling head 7. Through the hole 4 in the chamber 2 coolant is supplied into the gap 5 between the stem 1 and treated surface 6 under a pressure of at least 40 atm (400 MPa). Chip removal during drilling is carried out by the coolant flow through the internal channels 8 and 9 of the drill head and stem.

After the output of the drilling head 7 from the hole 12, the hole is finished during certain cutting conditions and the allowable wear of the tool. Instead of the drilling head 7, a reamer 10 is installed on the stem 1, while the coolant is supplied under pressure 40 atm (400 MPa) through the chamber 2 to the gap 11. In this case, the chips are removed during deployment through the drilled hole 12 forward in the direction of supply of the reamer.

The inventive method can be used, for example, for processing tube sheets, collectors. The workpiece is fixed on the machine. A tool stem with a drill head is installed in the machine spindle. Then the hole is drilled.

After the drill is removed from the hole, a reamer is installed on the stem, which is used to finish the hole.

With this method of processing deep through holes, the chips do not fall into the gap between the tool and the machined surface, thereby not damaging the latter during finishing.

The application of the proposed method provides a solution to the problem of improving the quality of processing deep holes:

- reduction of surface roughness;

- improving the accuracy of the machined holes;

- ensuring high quality surface layer, eliminating the formation of residual tensile stresses.

Claims (1)

A method of processing deep through holes, including drilling with the supply of cutting fluid (coolant) into the gap between the surface to be machined and the tool containing the stem and drill head, and chip evacuation when drilling with the coolant flow through the internal channel of the head and stem, characterized in that after the output of the drill head finish machining the hole under certain cutting conditions and the allowable amount of wear in one installation using a tool containing the same stem and reamer wherein, the chip removal during deployment is carried out through the drilled hole forward in the direction of supply of the reamer, and the coolant during processing is carried out under a pressure of at least 40 atm in an amount that ensures a steady flow of liquid in the direction of supply of the tool used.

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