RU2552616C1 - Method of mechanical processing for deep hole in tubular billet - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: processing is carried out by a device comprising a boring bar with cutting tools which is installed at eccentric bearings in a poppet sleeve with cutting and mandrelling teeth while the said sleeve is aligned in the initial position in an input steady rest before a working medium is supplied. The billet being processed is clamped between inner end faces of the input and output steady rests coaxially to them. Prior to the start of processing, centring chamfers are made on the inner end faces of the steady rests, mating chamfers are made on the end faces of the tubular billet, the chamfers are matched and sealed. Plugs are mounted on outer end faces of the input and output steady rests to provide for a common sealed cavity. The orking medium is supplied to the input steady rest via throttles during the direct working stroke, herewith rotary and translatory motion of the boring bar is combined with its planetary motion around the axis of the poppet sleeve. During the back stroke, the working medium is supplied to the output steady rest.

EFFECT: improved precision and quality of the processed surface, reliability of the processing procedure due to better chip removal.

2 cl, 2 dwg

Description

The invention relates to machine tool industry, in particular to methods for machining deep holes in pipe billets using metal cutting machines.

It can be used to carry out processes of particularly high precision boring, flashing, burning and internal grinding of holes in long pipes on small-sized machines, for example, while ensuring accuracy requirements for holes according to TU14-3- / 941 / -94.

A known method of fine boring in tension, carried out by the head of the stem, rigidly fixed in the stem and based on the surface of a machined deep hole of the tube stock with adjustable guides (Kirsanov S.V., Grechishnikov V.A., Shirtladze A.G., Kokarev V.I. “Tools for precision hole machining.” - M.: Mechanical Engineering, 2003.330 p.).

The disadvantage of the method of boring with a head with a stem is their large total length, which is always equal to or greater than the length of the processed tube billet.

A feature of the method is the presence of a process in which the stem works in tension, which avoids its vibrations at high cutting speeds and provides more reliable chip evacuation. This method is carried out by a head with adjustable guides and provides methods in which the workpiece is installed and verified on the machine, and the boring head (without plate) is rigidly fixed in the stem, is introduced to the entire length of the rear guide keys. When the micrometer nut is rotated, the guide keys of the head are radially moved until they are in close contact with the surface of the hole. The head is based, after which the head is passed through the hole of the part until the front guides extend beyond the opposite end of the part with a groove under the plate. A plate is inserted into the groove of the body, the head moves to the right to a position in which there would be a gap of 0.3 ... 0.4 mm between the cutting edge of the plate and the forming hole. The coolant supply, the rotation of the part and the feed of the head for the plate to enter the hole are turned on. The filling hole is bored to the position of the front guides fully entering the hole. Head (and coolant) feed and part rotation are disabled.

Then, by rotating the micrometer nut, the front guides are expanded to close contact with the surface of the hole, the boring process is carried out, and the head is based on the front hole and the rear guides in the hole being machined.

The considered method of high-speed fine boring involves the work of the stem in tension during its reverse working stroke. The direct course of the stem remains idle.

The disadvantage of this method is the need to use a long stem with a head, the total length of which is equal to or greater than the length of the hole being machined, which leads to longer lengths of devices and metal-cutting machines for implementing the boring method.

In addition, this method inevitably requires additional preliminary processing of the hole for the base for the front guides, i.e. time spent on preparation for final processing on other equipment and the use of additional equipment and production facilities. As a result, the technical and economic efficiency of such a process is reduced.

There is a similar method for boring deep holes with boring heads with self-aligning guide keys, differing only in that there is no need to set the guide keys to the required size before each passage through the hole (Kirsanov S.V., Grechishnikov V.A., Shirtladze A.G. ., Kokarev V.I. Tools for machining precision holes. - M.: Mechanical Engineering, 2003.330 s.). In this process, boring is conducted both in compression and in tension, that is, without loss of time for idling.

The disadvantage of the method is the need to use with the head and a long stem, the total length of which is equal to or greater than the length of the hole being machined, which leads to longer lengths of machines and devices for implementing the method of boring deep holes.

A known boring method with a design of the head with self-aligning guides having eight guide keys located in two rows of four keys in each (Minkov M.A. Technology of manufacturing deep precision holes. M., L .: Engineering, 1965. 176 p. )

In this case, it is possible to use a head with adjustable guide keys, which has guide keys made of textolite, located in a circle in front of and behind the floating plate, fixed in blocks.

A floating plate is inserted into the rectangular groove of the body of the boring head. The plate should move freely in the groove without distortions and jamming, which is ensured by the fit of H7 / g6 and the roughness of the mating surfaces not more than Ra = 0.32 ... 0.64 μm.

The disadvantage of this method is the need for preliminary processing of the surface of the processed deep holes under the front direction.

A known boring method using a tool for processing holes with a diameter of 40 ... 380 mm and a depth of up to 4000 mm in liners of pneumatic and hydraulic cylinders is presented by Sandvik Coromant (Sweden) (Sandvik Coromant Catalog, 2010, (http://www.coromant.sandvik .com)).

This combined cutting-deforming tool works as follows. With a direct stroke of the tool, the hole is bored with a floating two-blade boring block equipped with a hard alloy. In this case, the cage of the roller rolling head is shifted to the right by a certain distance from the support ring, and the head rollers do not touch the surface of the machined hole.

After the end of boring, the cutters of the floating block are recessed with the help of a pneumatic pressing device. Then the reverse feed of the tool is turned on, the holder of the rolling head is pushed to the left and abuts against the support ring. The rollers extend and begin to plastically deform the surface of the machined hole. After processing with the indicated tool, the surface roughness of the hole can be achieved up to Ra = 0.05 ... 0.20 μm, and its hardness as a result of hardening increases by 50%. Processing is carried out using oil-based coolant with extreme pressure additives.

The disadvantage of this method is the need for preliminary processing of the surface of the processed deep holes under the front direction.

Thus, a common drawback for deep hole machining methods is that pre-boring is preceded by high-speed fine boring, in which the main allowance is removed in diameter and the axis of the hole is straightened. The use of such methods leads to the need for a large number of manual techniques for setting up and adjusting the process, which leads to a significant investment of time and the inability to automate the process. In addition, this method inevitably requires additional preliminary processing of the hole for the base for the front guides, i.e. time spent on preparation for final processing on other additional equipment and production facilities.

As a result, the technical and economic efficiency of using such methods is reduced.

With a sufficient allowance, you can reduce the requirements for the preliminary boring operation and thereby increase its productivity by combining rough and finish boring and cutting-deformation sewing. The allowance left for finishing boring should provide an increase in the accuracy of the shape of the treated surface, removal of conical shape, ellipticity and other surface irregularities.

In the dissertation (Kosarev D.V. Improving the accuracy of shaping of internal threads by milling cutters with carbide inserts during planetary movement of the tool: abstract of dissertation ... candidate of technical sciences / D.V. Kosarev SamSTU; Stankin. - Moscow, 2010. - 232 p. ., a method of vortex threading, which is a high-speed milling by rotating cutters, is described. In the modern technical literature, this method is noted as a method of processing threads with planetary movement of the tool, providing good chip division.

However, the method is not intended for processing deep holes, and the absence of planetary movement mechanisms in the known construction makes it impossible for the machine to work with high feeds and increased removal of metal volume per unit time.

A known method of boring deep holes and a device for its implementation (Smolnikov N.Ya. Special machines for boring deep intermittent holes with spindles on outriggers: monograph / N.Ya. Smolnikov, VA Saninsky; Volgograd State Technical University. - Volgograd: RPK Polytechnic ”, 2004. - 176 p., Pp. 105-112).

This method of processing deep holes in tube billets involves the use of a device containing an input and output rest for securing a long tube billet between them, a cutting-deforming quill in the form of a sleeve with a boring bar inserted in it, containing a cutting tool and having a rotation drive of the boring bar and a feed drive, in which the processes of boring and cutting-deforming pulling are combined, setting the workpiece to be machined between the input and output bushings - lunettes coaxially with them, and the machining is carried out by a pinole with a boring bar installed in it with a cutter, the rotation drive of which is made in the form of a pneumatic turbine, and the feed drive in the form of a hydraulic cylinder with a piston acting on a pin equipped with a hollow cutting-deforming firmware, and when the method is implemented, the pin is installed before deep processing the holes are based in the initial position in the inlet sleeve, then they turn on the working feed, move the quill into the hole of the workpiece and bore, based on its deformation first, on the surface of the input sleeve-lunette and then on the surface of the hole to be machined, the boring tool is installed in front of the cutting-deforming firmware and the hole is bored rough, and the cutting teeth of the firmware increase its size to the diameter required for surface plastic deformation and eliminate boring errors arising from the wear of the cutter and its adjustment, and the mandrel teeth calibrate the hole in the final size, and at the end of the stroke, the quill is completely moved to the output sleeve and then perform a reverse stroke, in which the machined hole is recalibrated with firmware and returned to the initial position in the input sleeve-lunette.

The disadvantage of the method is the lack of efficiency due to the significant dimensions of the cutting machine and its mechanisms for feeding and rotating tools, due to the long intermediate pipe pushing the head of the rotating boring bar with the cutter and the intermediate shaft, which are longer than the pipes in this boring pattern, which leads to significant dimensions of the device, accordingly, the occupied production area and ultimately the increase in the cost of performing the machining operation is deep wow hole.

However, the proposed method is the closest technical solution, allowing to provide mechanical processing of holes in long pipe blanks.

The objective of the claimed invention is to develop a method of machining, a deep hole, which provides ease of processing, accelerating the preparation of the production of tube billets with a large length of machined holes in the face of increasing demands on the quality of processing, reducing the size of boring equipment and reducing the space occupied by the equipment.

The technical result is the provision of processes of high-performance contour milling, the formation of fine drainage chips and high-precision planetary internal grinding of deep and intermittent holes.

The technical result is achieved in a method of machining a deep hole in a pipe billet, in which the treatment is carried out by a device containing a boring bar with a cutting tool located on eccentric bearings in pins with cutting and mandrel teeth, which is based before the working medium is supplied in the initial position in the entrance rest, the workpiece to be machined is clamped between the inner ends of the input and output lunettes coaxially with them, and during the direct working stroke of the boring bar it carries out the post recessive and rotational movement, combining the processes of boring, pulling and burning of a deep hole, while feeding the boring bar before moving it into the output rest, then performing a reverse working stroke of the boring bar until it returns to its original position, while re-burning the deep hole being machined, in this case, before starting processing, centering chamfers are performed on the inner ends of the lunettes, response chamfers are performed on the ends of the tube billet, which combine and condense, in Plugs are installed at the ends of the input and output lunches, creating a single sealed cavity, the working medium is fed through the inductors during the direct working stroke into the input lunette, combining the rotational and translational movement of the boring bar with its planetary movement around the pinole axis, and during the reverse working stroke, the working medium served in the output rest.

The method of machining a deep hole in a tube stock is characterized in that a milling head cutter is used as a cutting tool.

The essence of the method of machining a deep hole in the tube stock is that before processing on the inner ends of the input and output lunches perform centering chamfers. Response chamfers are performed at the ends of the pipe billet. After this, the chamfers are combined and compacted, clamping the tube billet between the lunettes at a time. At the outer ends of the input and output lunettes, plugs are installed. This creates a single sealed cavity into which the working medium is supplied during the machining of a deep hole in the pipe billet. During the direct working stroke, the working medium is fed through the channel through the inductors to the input lunette, and during the reverse working stroke, the working medium is supplied in the same way to the output lunette. In this case, the rotational and translational motion of the boring bar is combined with its planetary motion around the pinole axis.

The use of a boring bar as a cutting tool for milling head cutters allows for reliable chip control, which is especially important when machining alloy and bearing steels of the ShKh grade, the blade processing of which is accompanied by the formation of drain chips, the division and chip removal of which in a limited space of the hole of a long tube billet with significant difficulties.

Figure 1 shows a longitudinal section of a device with a tubular billet installed between the inlet and the outlet, used in the implementation of the method.

Figure 2 shows the distribution scheme of the total allowance (Ztotal) for processing.

A method of machining a deep hole 1 in a pipe billet 2, in which the processing is carried out by a device 3, containing a boring bar 4 with a cutting tool 5, located in the quill 6 with cutting teeth 7 and mandrel teeth 8, containing a front cover 9, a back cover 10, eccentric bearings 11. On the inner ends of the input rest 12 and the output rest 13, centering back chamfers 14 and 15 are performed, and at the ends of the tube billet, counter chamfers 16 and 17 are made, which combine with the chamfers 14 and 15 of the rest, and hermetically sealed dissolved, pressing axially clamping the tubular blank 1 between the inner faces of the input and output backrest 12 backrest 13, coaxially with them. Before starting the treatment, the pinole 6 is based in the inlet 12 and hermetically seal its outer end with a plug 18, the outer end of the outlet lid 13 is hermetically closed with a plug 19, creating a single sealed cavity. Then, the working supply Sp is turned on, supplying the working medium under pressure P through the air channel 20 of the input rest 12 through the throttle 21 to the input rest 12 to the rear cover 10 of the pin 6 and then through the throttle 22 to the turbine 23, combining in time the rotational and translational motion of Sp boring bars 4 with its planetary motion Vр.н around the pinole axis. During the working feed, the boring bars 4 (direct working stroke) combine the processes of boring, pulling and mandreling of a deep hole. In this case, the supply of the boring bar 4 is carried out before it is transferred to the output lunette 13, and then the reverse stroke is carried out, while re-burning the deep hole.

In the process of moving the pinole 6, the deep hole 1 is processed until the pinole 6 exits into the output lunette 13, after which the reverse stroke is switched on, switching the pressure of the working medium to the output lunette 13 through its throttle 24 through channel 25, re-burning the deep hole 1 to full the pinoli exit 6 in the input lunette 12.

The distribution of the total allowance Ztotal (figure 2) for processing a deep hole 1 is as follows. The cutting tool 5 (milling cutter), installed in front of the cutting teeth 7, performs the machining of the deep hole 1 with Dzag rough, removing the majority of the allowance (Z black), which reaches the size D black (figure 2), then the cutting teeth 7 (made to reduce the numbers of the cutting teeth 8 as cutting-deforming teeth, which allows you to combine cutting and deformation processes with one front tooth 7), removing the allowance of Z half-sheet, increase its size to a half-diameter (D half-sheet), necessary for surface plastic deformation (PPD) with dorn teeth 8. This technique eliminates the errors in the shape of the deep hole 1 after rough machining arising from the wear of the cutting tool 5, the deformation of the pinole 6 and the error of adjustment. After that, the mandrel teeth 8 calibrate the deep hole 1, removing the remnants of the stock (Zclean) into the final finishing dimension Dclean along the entire length of the workpiece before reaching the exit rest 12.

The sequential vortex-milling and cutting-deforming flashing of the deep hole 1 are carried out when, simultaneously with the longitudinal feed, the working medium is fed through the throttle 22 in the rear cover 10 of the pin 6 to the turbine 23, creating torque on the boring bar 4 and the cutting force on the cutting tool 5, combining in time, the longitudinal feed of the pinole 6 and the planetary rotation V6 of the boring bar 4. By rotating at a speed Vр.н <Vб of the cutting tool 5 about its axis, in the deep hole to be machined, 1 remove the total Zobsch allowance (2) by vihrefrezerovaniya and plastic deformation of the surface RPM, while based on their surface to be treated turf teeth 8 with interference. At the same time, the tightness ensures the rigidity of the base of the pin and, accordingly, the accuracy of processing. Keeping the pressure during the direct working stroke, the pressure supply to the direct working stroke is completed after the pinole 6 is transferred to the internal cavity of the output lunette 13, then the air pressure is switched to the output lunette 13 using the right reversing valve 26 into the cavity between the plug 19 of the output lunette 13 and the front with the cover 9 of the pin 6, performing the reverse stroke of the pin 6, re-burnishing of the processed deep hole 1. After the pin 6 goes back to the initial position in the input lunette 12, I turn off the pressure t, the tube stock 2 is unfastened and removed.

To repeat the processing of the next tubular billet 2, the pressure is switched using the left reversing valve 27 and all of the above methods of controlling pressure and transitions of operations associated with combining boring, drawing and mandreling are repeated.

The claimed method of machining a deep hole provides ease of processing, reducing the time for preparation of production and flexibility of production when changing to a different pipe size in the face of increasing demands on the quality of processing, reducing the size of boring equipment and reducing the space occupied by the equipment.

For example, when boring casing pipes for drilling equipment, the preparation of production is reduced to replacing the pin rests of the appropriate size on one bed, which eliminates the need to provide a separate size for the boring machine for each size. As a result of the application of the method, it is possible to reduce the dimensions of the equipment used, improve the quality of the machined surface, the accuracy of processing deep holes in long pipe blanks, and combine rough and finish machining of the processed surface of the pipe blank. In addition, the method provides an increase in the reliability of the machining of a deep hole in a pipe billet by improving chip control.

Thus, the claimed method of machining a deep hole in a tube stock provides processes of high-performance contour milling, the formation of fine drainage chips and high-precision planetary internal grinding of deep and intermittent holes.

Claims (2)

1. A method of machining a deep hole in a tubular billet, including combining the boring, drawing and durning of a deep hole using a device containing a boring bar with a cutting tool, which is placed on eccentric bearings in pins with cutting and mandrel teeth, and is based before applying the working medium in the initial position in the input rest, while the workpiece is clamped between the inner ends of the input and output rests coaxially with them, and during progressive and rotational movements are notified of the working stroke of the boring bar, and the boring bar is fed before it is transferred to the output rest, after which the boring bar is reversed until it is returned to its original position, ensuring that the processed deep hole is re-burned, characterized in that before processing on the inner ends of the lunettes, centering chamfers are performed, and on the ends of the tube billet, response chamfers, which combine and condense, are performed on the outer ends of the inlet and outlet The plugs install plugs to create a single sealed cavity, while the working medium is fed during the direct working stroke into the input lunette through the throttles when the rotational and translational movements of the boring bar are combined and the planetary movement around the pinole axis is communicated to it, and during the reverse working stroke, into the output lunette . 2. The method according to claim 1, characterized in that a milling head with cutters is used as a cutting tool.

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