CN108723715B - Method for processing nozzle shell by using bar stock - Google Patents

Abstract

The invention provides a method for processing a nozzle shell by using a bar stock, which comprises the steps of taking the bar stock as a blank, turning a mounting plate and an eccentric cylinder for processing and forming a rod part of the nozzle shell on the bar stock by adopting a turning method, and drilling a plurality of mounting holes on the mounting plate; then processing the rod part and the head part of the nozzle shell; machining the eccentric cylinder to form a cone, cutting the cone into a plane and removing the allowance on one side of the profile of the rod part to form the rod part of the nozzle shell; raising the bar in the horizontal direction by an angle to enable the axis of the head to be in the horizontal direction, roughly cutting the shape of the head by adopting a linear cutting method, processing the rear end face of the head into a plane, and performing post-positioning by using the plane to perform subsequent fine machining of the head; and then processing the eight grooves at the head part, the deep holes of the main oil way, the deep holes of the auxiliary oil way, the main spray hole and the like. The invention saves the design and manufacturing time of forging and casting blank, saves the production cost and reduces the production period.

Description

Method for processing nozzle shell by using bar stock

Technical Field

The invention relates to a method for processing parts such as a nozzle shell, in particular to a method for processing the nozzle shell by using a bar stock.

Background

Currently, more and more new aircraft engines are in the development phase in succession. The fuel nozzle is an important element of a fuel system of an aviation gas turbine engine, and connects a fuel supply regulating system of the engine with the fuel system to provide continuous power output for an airplane. The nozzle shell is known for its complex external structure, large difference, large space size and technical conditions, and large manufacturing difficulty. The device not only has the spatial external dimension which is difficult to process and detect, but also has the precise internal profile dimension which is matched with precise parts such as a fuel nozzle, a rotational flow core and the like, and the processing difficulty is very high.

At present, in the blank manufacturing aspect, domestic nozzle shell blanks are in forging and casting structures, the blank manufacturing difficulty is high, the period is long, two or thirty working procedures are usually needed from raw materials to the final blank manufacturing, the number of occupied equipment is large, the production period is as long as 2-3 months, a plurality of forging dies or casting dies are needed in the manufacturing process, and the production cost is high.

With the rapid development of additive manufacturing technology in recent years, nozzle shell blanks adopting 3D printing have been applied to advanced scientific research machines, but the manufacturing cost is very high, the cost of one blank reaches tens of thousands yuan, and the manufacturing precision needs to be further improved.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a method for processing a nozzle shell by using a bar stock, which saves the design and manufacturing time of forging and casting blank, saves the production cost and reduces the production period.

The invention is realized by the following technical scheme:

a method for processing a nozzle shell by using a bar stock comprises the steps of taking the bar stock as a raw material, roughly removing the surplus of the raw material by adopting a turning method to obtain a rough appearance structure of the nozzle shell, and then carrying out finish machining to obtain the nozzle shell.

Preferably, the method specifically comprises the following steps: turning a mounting plate and an eccentric cylinder for processing and forming a rod part of the nozzle shell on the bar by adopting a turning method, and then drilling a plurality of mounting holes on the mounting plate; and positioning the lower surface of the mounting plate and the mounting hole, and processing the rod part and the head part of the nozzle shell.

Furthermore, a center hole and a process table are processed on the end face of one end, close to the mounting plate, of the bar, and the process table is coaxial with the eccentric cylinder and used for clamping and aligning in the subsequent procedures.

further, the machining method of the nozzle shell rod part comprises the steps of calculating an included angle α 4 between the rod part center line and the left side contour line of the rod part, calculating an included angle α 5 between the rod part center line and the right side contour line, machining the eccentric cylinder by taking the larger value of α 4 and α 5 as a half angle to form a cone, and machining to form the nozzle shell rod part.

Further, after the cone is machined, the cone is cut into a plane by a linear cutting method, a remelted layer after the linear cutting is removed, and the allowance on one side of the molded surface of the rod part is removed by a four-axis linkage mode of a milling center to form the rod part of the nozzle shell.

further, the processing method of the nozzle shell head comprises the steps of firstly raising a bar by an angle α 6 along the horizontal direction to enable the axis of the head to be in the horizontal direction, roughly cutting the shape of the head by adopting a linear cutting method, processing the rear end face of the head into a plane, and carrying out post positioning by using the plane to carry out subsequent fine processing of the head.

Furthermore, after the shape of the head of the nozzle shell is machined, the inner cavity groove of the drill bit is machined by adopting an electric spark machining method to machine eight arc-shaped grooves at the head.

Further, after the head arc-shaped groove is machined, a deep-hole drilling machine is used for machining the main oil way deep hole and the auxiliary oil way deep hole, then an oil inlet joint part groove is milled, a reaming hole is expanded, and an auxiliary oil way oil inlet hole is machined.

Further, after the auxiliary oil way oil inlet hole is machined, the main spray hole is roughly machined by adopting an electric spark machining method, then reaming is carried out by adopting a reamer, and the main oil way outlet groove and the auxiliary oil way outlet groove are machined by adopting the electric spark machining method.

Preferably, the maximum outline dimension of the nozzle shell is placed along the axis of the bar stock, the two-dimensional view model of the nozzle shell is installed inside the two-dimensional view model of the bar stock in a ratio of 1:1 so as to analyze and determine the position of the machining allowance of the bar stock, and then the nozzle shell is machined.

Compared with the prior art, the invention has the following beneficial technical effects:

the invention directly adopts the bar stock to process the complicated nozzle shell, saves the design and manufacturing time of forging and casting blank, saves the production cost and reduces the production period by about half. Compared with the problem that the reference is difficult to determine during forging and casting processing, the method has the advantages that the selection of the reference is wider during bar processing, the precision is higher, the accumulated error is favorably reduced, and the quality of parts is improved. The part delivery is not limited by the blank supply condition any more, and the delivery initiative can be controlled. The qualification rate of the parts is not influenced by the manufacturing precision and consistency of the forging and the casting blank, and the qualification rate is further improved. The standard is easy to select and the shape is regular when the bar is processed, the precision is high, the design difficulty of a processing clamp and a measuring tool is greatly reduced, the dependence degree on a special tool is low, and the production cost is saved.

Furthermore, the mounting plate and the mounting hole are the design reference and the processing positioning reference of the whole part and are the most main references in the whole part design and processing process, and the mounting plate and the mounting hole are basically used for positioning in the processing of other parts, so that when the nozzle shell is processed by using a bar material, the mounting plate and the mounting hole are firstly processed, and then the subsequent processing is carried out. The eccentric structure generally exists with the mounting panel center in nozzle housing pole portion, consequently should find out the eccentricity when roughly going the surplus, the eccentric cylinder of car, just so can guarantee that pole portion surplus obtains effectual getting rid of.

Furthermore, because the size of the woollen is large, in order to facilitate the clamping and alignment of the subsequent procedures, a center hole and a process table need to be processed at the oil inlet end, and the eccentric cylinder and the process table can be pushed together to be tightly processed in the subsequent procedures, so that the clamping stability in the subsequent turning process can be ensured. And the center of the process table is superposed with the center of the eccentric cylinder, so that the position of the eccentric cylinder can be determined by aligning the position of the process table, and the center jacking force of the center can be ensured to be over against the center of the main shaft of the machine tool when the conical surface of the rod part is further processed.

furthermore, in the machining process of the rod part of the nozzle shell, when the allowance is removed, the eccentric cylinder is machined to form a cone by taking the larger value of α 4 and α 5 as a half angle, otherwise, an over-cutting phenomenon may occur to cause the rod part to be meat-deficient.

Furthermore, because the two sides of the rod part are planes, the rod part after turning is a cone, the cone must be processed into the plane at the moment, the process of cutting the plane by linear cutting is the fastest process method, after the cone is processed into the plane, one side of the molded surface of the rod part has a small amount of process allowance, and the allowance is removed by processing in a four-axis linkage mode by means of a milling center, so that the accurate profile shape of the rod part is obtained.

Furthermore, when the head of the nozzle shell is machined, the rear end face of the head is an inclined plane, so that the rear end face of the head is machined into a plane before the head is machined, the plane can be used for post-positioning during fine machining of the head, and the positioning accuracy can be improved.

furthermore, raise the head round platform angle α 6 along the horizontal direction, make the head axis be in the horizontal direction, guarantee the head position degree strictly promptly, can guarantee that follow-up finish machining nozzle shell head can go on smoothly, otherwise will be because the excircle lacks meat and can't process out when follow-up finish machining head excircle.

Further, since the head octant groove is discontinuous, the machining cannot be realized by the turning method, and therefore, the machining is realized by the electric discharge machining method.

Furthermore, the deep holes of the main oil way and the auxiliary oil way can not be drilled by a common drilling machine or a machining center due to the fact that the length-diameter ratio of the deep holes of the main oil way and the auxiliary oil way is more than 30, the two ends of the deep holes can not be subjected to butt joint machining due to the limitation of the structure of parts, and only one-step machining forming by external feed of the parts can be selected, so that the deep hole drilling machine is selected for machining.

Furthermore, the main jet hole is small in diameter and is an oblique-jet type small hole, the main jet hole is influenced by a special structure of the shell, the design difficulty of the clamp is high, the drill bit is easy to break in the clamp machining process, the drill bit is difficult to take out when being broken inside the shell, and the actually machined position of the drill bit deviates from the theoretical position under the comprehensive action of a plurality of factors in the drilling machining process, so that the main jet hole cannot be obtained by adopting a mechanical machining method and is directly machined by adopting electric spark.

Furthermore, the maximum outline size of the part is placed along the axis of the bar, the part outline drawn in a ratio of 1:1 is installed in the bar by adopting an installing method, so that the size of the bar can be determined, the part where the machining allowance of the bar is located can be analyzed and determined, the machining of the nozzle shell is facilitated, the phenomena of machining missing and over-cutting are prevented, and the method is particularly suitable for process analysis of parts with complex structures and shapes.

Drawings

FIG. 1 is a schematic view of a fuel nozzle housing of an engine.

Fig. 2 is a schematic diagram of wool selection.

FIG. 3 is a schematic diagram of rough machining of a blank.

FIG. 4 shows the upper end of the mounting plate.

Fig. 5 is a schematic view of turning an eccentric circle.

FIG. 6 is a schematic view of a lathe table.

Fig. 7 is a schematic view of mounting hole machining.

Fig. 8 is a schematic view of the stem angle.

Fig. 9 is a schematic view of the stem machining.

Fig. 10 is a schematic view of two side surfaces of a wire-cut rod.

Fig. 11 is a schematic view of a finish milled shank profile.

Fig. 12 is a schematic view of the outline of the wire cutting head.

FIG. 13 is a schematic view of a positioning plane of the wire cutting and grinding machine.

FIG. 14 is a schematic view of a lathe fixture.

Fig. 15 is a schematic view of a finishing head.

Fig. 16 is a schematic view of an eight-groove electric discharge machining.

FIG. 17 is a schematic view of an eight-groove chamfer.

Fig. 18 is a schematic view of head bevel machining.

Fig. 19 is a schematic view of deep hole processing of the secondary oil passage.

Fig. 20 is a schematic view of the milling oil inlet nipple portion groove.

FIG. 21 is a schematic view of the machining of an oil inlet of an auxiliary oil passage.

Fig. 22 is a schematic view of an electric discharge machining main nozzle hole.

FIG. 23 illustrates the machining of the main oil gallery outlet grooves.

In the figure: 1 is the head, 2 is the pole portion, 3 is the mounting panel, 4 is the mounting hole, 5 is oil inlet portion, 6 is the arc wall, 7 is protruding muscle, 8 is the main jet orifice, 9 is the bar, 10 is eccentric cylinder, 11 is the technology platform.

Detailed Description

The present invention will now be described in further detail with reference to specific examples, which are intended to be illustrative, but not limiting, of the invention.

In this example, a processing method will be described by taking the nozzle case GH3536 as an example. Referring to fig. 1, the nozzle casing structure can be divided into four parts, i.e. a head part 1, a rod part 2, a mounting plate 3 and an oil inlet part 5, in this example, the nozzle casing is a double-oil-way casing without a valve, and a main oil way and an auxiliary oil way penetrate through the inside of the casing and are respectively provided with an independent oil inlet. The central line of the nozzle head 1 and the mounting plate 3 form a certain space included angle.

The parts from top to bottom are described as follows:

the oil inlet can be divided into a main oil inlet and an auxiliary oil inlet.

The mounting plate 3 is provided with four mounting holes 4 for fixing the nozzle to the outer wall of the casing by means of bolts.

The inner cavity of the rod part is provided with a main oil way and an auxiliary oil way, the diameters are phi 6 and phi 4 respectively, the length exceeds 120, the length-diameter ratio reaches 20-30, and the processing difficulty is very high.

The head 1 of the nozzle shell is the core part of the whole part, 8 arc-shaped grooves uniformly distributed along the circumference are arranged on the large excircle of the head 1, and 8 convex ribs are respectively separated by the 8 arc-shaped grooves and are positioned at the positions of 8 main spray holes.

The invention directly processes the nozzle shell with a complex profile through a bar stock, and two specific analysis methods, namely a loading method and a step approximation method, are used in the processing process.

The 'loading method' is to load a two-dimensional view model of a part (nozzle shell) 1:1 into a blank (bar), so that the part where the machining allowance is located can be found very intuitively, the phenomena of machining missing and over-cutting are prevented, and the method is particularly suitable for process analysis of parts with complex structural shapes.

The step-by-step approximation method is characterized in that a part with machining allowance is determined on the basis of a loading method, then the allowance is removed step by step, and a final view model is slowly approximated until all the parts are matched, so that the machining is determined to be finished.

The processing method will be specifically described below.

The part material is GH3536, is delivered in a solid solution state, has high hardness, is processed to a final shape from a bar stock, and has large machining allowance because all the inner and outer surfaces need to be machined. Since the blank is of a bar structure, all final profiles of the part need to be formed by machining and other machining methods, and therefore the overall profile structure of the nozzle housing should be roughly machined.

The specific processing method comprises the following steps.

(1) And determining the size of the outer contour by observing the outer contour structure of the whole nozzle shell. When the blank adopts the bar 9, the maximum outline dimension of the part should be placed along the axial direction of the bar 9 as much as possible. The excircle of the mounting plate is mostly of a rotary or approximately rotary structure, and the size of the excircle of the mounting plate determines the diameter of the bar 9.

The part was placed horizontally, approximately L1 in length, with the mounting plate maximum diameter Φ D1. As previously mentioned, the maximum profile dimension of the part should be placed along the axis of bar 9 and the dimensions of bar 9 determined by "loading" the 1:1 drawn part profile into bar 9 as shown in FIG. 2.

As can be seen from fig. 2, the diameter of the bar 9 is preferably selected to be Φ D2, and when the length of the bar 9 of a single nozzle shell is L2, the processing of parts can be satisfied, so the bar 9 with the length of L2 is cut by a blanking cutter first. Wherein Φ D2 is greater than Φ D1, and L2 is greater than L1.

(2) Considering the maximum rod allowance, the blanked bar 9 is first machined uniformly into a step-like structure as shown in fig. 3, with a rod diameter Φ D3 smaller than Φ D1.

(3) The nozzle shell is characterized in that a mounting plate and a mounting hole are the design reference and the processing positioning reference of the whole part and are the most main reference in the whole part design and processing process by combining the processing experience of the traditional nozzle shell, the mounting plate and the mounting hole are basically used for positioning in the processing of other parts, and when the nozzle shell is processed by adopting a bar stock, the most basic process design principle is followed, so that the mounting plate and the mounting hole are processed firstly, and the processing quality of the mounting plate and the mounting hole affects the processing quality of the whole part by the diameter.

The appearance of the whole part is observed, only the mounting plate is of a rotary structure, and the mounting plate is obtained by adopting a turning method and is the easiest part to process on the whole part. During rough machining, the rest three parts of the shell, namely the head part, the rod part and the oil inlet part are approximately imagined to be a rotary structure, so that the allowance of a part can be roughly removed by adopting a turning method, the approximate appearance structure of the part is obtained, the mounting plate is turned out, then four holes are drilled on the mounting plate, and the machining schematic diagram is shown in fig. 4. And the subsequent process positions the bottom surface of the mounting plate and two diagonal holes in the four holes, and compresses the upper surface of the mounting plate, so that the fine machining of the rest parts of the part can be finished.

(4) The nozzle housing stem and mounting plate center typically have an eccentric configuration, so the eccentric configuration must be turned when the margin is removed. The eccentricity must be accurately calculated by 1:1 mapping, otherwise the actual shape of the rod part will deviate from the theoretical shape, and the phenomenon of partial meat deficiency is caused. In this example, the eccentric distance between the center of the stem portion and the center of the outer circle of the mounting plate was L3 by theoretical measurement and graphical analysis.

After processing according to fig. 4, the upper surface of the mounting plate has been processed into position. As can also be seen from fig. 4, the portions where the machining allowance is the largest remain at the shaft portion and the head portion, and therefore, the machining allowances of the shaft portion and the head portion should be further removed next. Fig. 4 shows that the rod part is deviated from the lower part of the woollen material, the difference between the central position of the rod part and the central position of the mounting plate is L3, so that the eccentric distance of L3 must be found out during processing through a common lathe, the allowance of the rod part can be effectively removed, the eccentric cylinder 10 with the diameter phi D5 is lathed, and the processing schematic diagram is shown in fig. 5.

(5) The size of the rough material of the part is large, and a tip hole and a process table need to be processed at two ends of the part in order to facilitate clamping and alignment of subsequent processes.

And the subsequent process comprises the steps of positioning the upper surface of the processed mounting plate, positioning and clamping the eccentric cylinder, removing the allowance of the rod part and the head part, and pressing the outer circle of the vehicle by using a tip because the part is deep and long in suspension depth and a central hole is formed in the rear of the flat end surface. The machined eccentric cylinder, as can be seen in fig. 5, has already approached the final profile of the shank. When the machining is carried out, the lower surface of the mounting plate still has allowance, and the allowance is removed when the taper surface of the rod part is turned subsequently, so that the generation of the cutter connection can be effectively prevented.

In order to ensure that correct clamping processing of the part can be smoothly realized when four holes are drilled in the milling center, and meanwhile, because the length of the part is long, in order to ensure the stability of clamping during subsequent turning processing, a process table 11 with a tip hole needs to be processed on the end face of the other end of the part, so the processing content of the process is to turn the process table 11, and the processing schematic diagram is shown in fig. 6.

The center of the process table 11 is superposed with the center of the eccentric cylinder 10 where the rod part is located, so that the position of the eccentric cylinder 10 can be determined by aligning the position of the process table 11, and the center jacking force of the center can be ensured to be over against the center of the main shaft of the machine tool when the conical surface of the rod part is further processed.

(6) In order to ensure the stability of clamping, the mounting hole and the oil inlet connecting nozzle part are processed in place in front of the conical surface of the lathe rod part. The lower surface of the mounting plate 3 is used as a positioning surface to clamp the eccentric cylinder 10, the shape of the oil inlet connector is milled, the mounting hole 4 is drilled and hinged, and the processing schematic diagram is shown in fig. 7.

(7) the shape of the rod part of the part is analyzed, as shown in fig. 8, the included angle between the contour lines on the two sides of the profile of the rod part is α 1, the included angle between the left profile of the rod part and the center line of the head part is α 2, and the included angle between the normal line of the mounting plate (the approximate center line of the rod part) and the center line of the head part is α 3, so that the included angle between the center line of the rod part and the left contour line of the rod part is α 4- α 2- α 3, and the included angle between the center line of the rod part and the right contour line is α 5- α 1- α.

when the allowance is further removed, a turning method is still adopted, but turning is a rotary structure, a conical surface needs to be turned by taking the larger value of α 4 and α 5 as a half angle, the angle of the machined conical body is α 7, and α 7 is twice of the larger value of α 4 and α 5, otherwise an over-cutting phenomenon possibly occurs to cause the rod part to be fleshy, meanwhile, the position of the head part of the nozzle shell is ensured to be just processed, the molded surface of the rod part 2 is very close to the actual contour of a part, the lower surface of the mounting plate 3 can be processed to the final position, and the processing schematic diagram is shown in fig. 9.

The processing equipment is still an ordinary lathe, the soft claw is used for clamping the eccentric cylinder 10, the suspension depth of the part is long, and a process table 11 close to one end of the mounting plate needs to be tightly propped by a tip.

Because the two sides of the rod part are planes, the machined rod part is a cone, the cone must be machined into the planes at the moment, and the adoption of linear cutting for cutting the planes is the fastest machining method, but the remelted layer after the linear cutting must be removed. The schematic processing is shown in fig. 10.

At this time, the molded surface of the rod part 2 has a slight machining allowance except for the leftmost side, and the rest parts of the molded surface of the rod part completely conform to the outline of the rod part. In order to obtain a precise profile of the rod portion, a machining process must be arranged. The milling center can be used for processing in a four-axis linkage mode, and the processing schematic diagram is shown in figure 11.

(8) Through the processing of the procedures, the outer contour of the rod part 2 of the nozzle shell and the mounting plate 3 are all in place, at the moment, a process table is reserved at the oil inlet joint part, and the subsequent procedures are not used, so that the oil inlet joint part can be removed, and the shape of the part can be finished to the final size requirement. The method is suitable for milling by adopting a milling center, large allowance can be roughly removed by adopting linear cutting, then the final size is ensured by milling, and the positioning and pressing positions are the same as those before.

(9) The head of the nozzle housing has not been machined at present, and the inner and outer profiles of the head are the most difficult parts to machine on the whole part, and the machining of the head is described in detail below.

When the head of the nozzle shell is machined, the shape of the head is roughly cut by adopting a linear cutting method, and a certain allowance is reserved for fine machining. Because the rear end face of the head is an inclined plane, the rear end face of the head is machined into a plane before the head is machined, and the plane can be used for post-positioning when the head is finely machined, considering that the cutting force is large when the head is machined and the positioning accuracy of the inclined plane is poor.

When the head is processed, the lower surface of the mounting plate 3 and the mounting hole 4 are preferably adopted for positioning, so that the processing reference and the design reference are superposed, and the processing error is minimum. The head part before machining is a round table, the machining allowance is large, the final head part outline cannot be obtained through one-time machining, and the machining needs to be carried out by a plurality of working procedures. First, a first step is performed to remove large margins roughly by using a wire cutting method, as shown in fig. 12.

in order to ensure that the subsequent finish machining of the head of the nozzle shell can be smoothly carried out, the angle α 6 must be strictly ensured when the outer circle of the head is cut by a line in the process, the vertical distance between the axis of the head and the center of the pitch circle of the mounting hole is L4, namely the position degree of the head is strictly ensured, otherwise, the outer circle of the head cannot be machined due to the shortage of meat in the outer circle during the subsequent finish machining of the head, the position of the head is far away from the mounting plate 3 (a positioning position), no special measuring tool is used for 100% detection, all universal methods are adopted for machining and detection in the machining process, and therefore, the machining difficulty of the sizes α 6 and L4 is very high when the outer circle of the head is cut by the line.

A certain finishing allowance is reserved when the outer circle of the head part of the wire-electrode cutting machine is cut.

The head is preferably finished by turning. When the inner shape is finely turned, an inner hole with a larger diameter needs to be machined in the middle of the head, the removal allowance is large, the acting force along the axis of the head is very large during drilling, and a supporting surface needs to be added behind the head in order to prevent the head from being pushed to be deviated. Therefore, it is necessary to perform wire cutting and surface grinding, i.e., first roughly cutting the shape of the head by wire cutting, machining the rear end face of the head into a flat surface, and performing post-positioning by using the flat surface when finishing the head. As shown in fig. 13.

the nozzle shell part is large in size, the distance between a processing part and the pressing part is far, and a combined clamp is not suitable for both the aspects of structural complexity and safety of the clamp, so that a special lathe clamp is designed in the processing process, a clamp schematic diagram is shown in figure 14.

During machining, the excircle of the four-jaw clamping fixture is firstly utilized to align the circumferential runout within 0.03, so that the theoretical position size L4 of the head can be effectively ensured. The rear positioning cylinder at the central position on the clamp is tightly attached to the ground plane at the rear end of the head of the part, so that the rear positioning effect is achieved, and huge axial force is offset during drilling and machining.

the processing of the inner and outer profiles of the nozzle housing head is the biggest difficulty in the processing of the whole part, but the premise is to ensure that the outer circle of the nozzle housing head 2 can be completely processed, namely the reason why the sizes alpha 6 and L4 must be strictly ensured when the outer circle of the head is cut linearly, and the schematic diagram of the head processing is shown in FIG. 15.

(10) The processing of eight arc-shaped grooves at the head part (head part eight grooves for short) is another difficulty in processing the head part of the nozzle shell. The head octant groove is discontinuous, and the processing cannot be realized by the lathing method, so the head octant groove cannot be combined in the lathing process.

In this example, the diameter of the bottom of the head eight-groove is phi 43.4_-0.08Requires a nozzle tip of phi 35.4^+0.2 ₀The coaxiality of the center of the hole is phi 0.05, and the inner hole of the part must be aligned by 100% in the machining process. The width of the convex rib separated by two grooves is 4.5_-0.05And 4.5_-0.08Meanwhile, the two sides of the eight grooves and the root switching R are both R0.5, if a milling center is adopted for processing, a large milling cutter is used for rough allowance removal, and then a phi 1 ball-end milling cutter is used for finish processing. The length of the phi 1 ball end mill cutter is only about 35mm, the diameter of the clamping part is phi 4, the effective cutting edge is very short and is only about 1.5, and therefore, the processing is very slow and specialThe cutter is easy to be cut, and the processing difficulty is very high.

After comprehensive analysis, the common machining method cannot meet the requirement of machining of the eight-groove part, and a special machining process, namely electric spark machining, must be adopted. However, it is difficult to secure the width dimension of the rib after the electric discharge machining, and a re-melted layer of 0.03 to 0.05 thickness is formed on the surface of the part. Due to the particularity of the eight-groove part structure, the remelted layer is difficult to remove, and the diameter of the bottom of the eight-groove cannot be ensured by manual polishing. Considering that the eight grooves are mainly matched with the eight convex teeth on the vortex device, the eight grooves only need to be matched with the vortex device tightly, and the remelting layer has no influence on the work of the vortex device. Therefore, by consulting the designer, the remelted layer is allowed to remain on the surface of the eight grooves, so that the process can be realized by adopting the electric discharge machining method.

During electric spark machining, the center line of the head of the part is placed in the vertical direction by using the clamp, the part to be machined is ensured to be vertically upward, and the clamp also adopts one surface of each of the two holes for positioning and clamping. After the part is clamped, 100% of inner holes of the center hole of the head part need to be aligned to jump within phi 0.05, so that the coaxiality phi of the eight grooves to the inner holes is ensured to be 0.05. The processing is carried out until the dimension of the convex rib is basically in place and has a little margin, and the final dimension can be achieved by adopting a bench filing method subsequently. The schematic view of the part processing is shown in fig. 16.

The eight grooves also have different depth dimensions, wherein the depth dimensions of two grooves in the AB-AB cross section are the same, and the depth dimensions of the other six grooves are the same. But this does not pose any threat to electrical discharge machining. The special forming electrode is adopted in the electric spark machining, so that one-time machining can be realized, all sizes can be directly guaranteed, and the machining efficiency is greatly improved. The size precision mainly depends on the actual size precision of the formed electrode and the precision of the machine tool, so the size of the electrode is very important, and the structure of the special electrode is completely the same as that of the eight-groove structure.

As can be seen from the three-dimensional model of the final part, the head part and the two sides of the head part of the eight-groove are provided with chamfers, and the chamfer angle cannot be machined by electric sparks, so that the notch of the eight-groove is required to be chamfered after the eight-groove machining is finished.

The chamfer can be milled by adopting a milling center, but the processing efficiency is low, and the chamfer can be realized by adopting four-axis linkage, so that the difficulty is higher. Considering that the function of the eight-groove chamfering is only to reduce weight and facilitate assembly, chamfering operation can be directly carried out by a bench worker, and the machined angle can completely meet the design requirement although the appearance is poor. Meanwhile, the rib after electric discharge machining is clamped to the final size, and the machining schematic diagram is shown in fig. 17.

At this point, the internal and external shapes of the nozzle housing head have been substantially finished.

(11) After the inner shape of the head is processed, the plane boss reserved at the rear end of the head is not used, so that the head can be cut off. When removing, the milling method can be adopted for processing, and the processing equipment can adopt a milling center.

Of course, because the machining allowance is large, the direct milling time is long, and the machining can be carried out by a method of firstly carrying out linear cutting to roughly remove the large allowance and then carrying out milling to ensure the final size. The schematic processing is shown in fig. 18.

(12) The deep hole processing of the main oil path and the auxiliary oil path is a big difficulty in processing the nozzle shell.

Taking the deep hole processing of the auxiliary oil path as an example, the length-diameter ratio reaches more than 30, the drilling by adopting a common drilling machine or a processing center can not be realized at all, and the two ends of the workpiece can not be butt-jointed and processed under the limitation of the structure of the workpiece, and only the workpiece can be processed and formed by feeding from the outside of the workpiece once. A deep hole drilling machine 1A1TLF-660.4 is selected for machining.

The deep hole drilling machine is specially used for processing deep holes of various shell parts, blade parts and long shaft parts, the maximum processing length-diameter ratio can reach 50 according to the precision requirement of the deep holes of the parts, the processing diameter range can be different from phi 3 to phi 20, and the deep hole drilling machine is suitable for deep hole processing of various metal materials.

The deep hole to be processed has a certain offset from the hole opening to the hole bottom under the influence of the part material, the precision of a machine tool and a cutter. The offset is an important index for measuring deep hole processing, and is the maximum deviation amount of the axis of an actually drilled hole and the rotation axis of a workpiece in the process of drilling in the rotating mode of the workpiece. If the through hole is machined on the long shaft, the offset from the inlet to the outlet can be directly measured. The offset is generally about 0.2 over a length of 100 mm.

The special tool gun drill is adopted in the machining, the tool is a single cutting edge, automatic chip removal and cooling lubrication can be realized, the tool has a good guiding function, and the characteristics of deep hole machining are met. The V-shaped groove in the gun drill mainly plays a role in chip removal, a long hole penetrates through the inside of the cutter, the long hole is a channel through which high-speed cutting oil flows, the long hole mainly plays a role in cooling and flushing scrap iron, and the cutting oil rebounds through the bottom of the hole under the action of high pressure to flush the scrap iron out of the V-shaped groove. In the processing process, a combined clamp is selected for clamping, one surface of each hole is still adopted in the positioning mode, and the processing schematic diagram is shown in fig. 19.

The processing content of the main oil way deep hole is basically the same as that of the auxiliary oil way deep hole.

(13) After the deep holes of the main oil path and the auxiliary oil path are processed, a plurality of step holes are left in the inner cavity of the rod part of the nozzle shell and are not processed in place, and the step holes comprise an oil inlet connecting nozzle part runner type cavity. Therefore, the next procedure is to mill the oil into the groove of the oil nipple part and expand the reaming hole. Because the deep hole is perpendicular to the mounting panel, consequently can adopt modular fixture to place the part vertically during processing. The schematic processing is shown in fig. 20.

The machining equipment still adopts a milling machining center MV-45. In the actual processing process, because the step deep hole needs to be processed by using a lengthened drill bit, the step deep hole is difficult to realize in a processing center, the step deep hole is allowed to be processed on a four-axis row type common drilling machine for one time, the equipment has four main shafts, and cutters with different diameters can be clamped respectively, so that a plurality of elements can be clamped and processed on parts at one time.

(13) The oil inlet hole of the auxiliary oil way is an inclined hole, in the example, the included angle between the oil inlet hole and the mounting plate is 45 degrees, so that after the two holes are adopted and positioned and clamped, the whole part must be rotated by 45 degrees to ensure that the holes to be machined are placed along the vertical direction, and the machining schematic diagram is shown in fig. 21.

Because the oil inlet depth is shallow, a drill hole needs to ream a platform bottom step hole, and the processing equipment can select a processing center and also can select a common drilling machine.

At this point, the main inner and outer cavities of the nozzle casing are basically machined, but some minor auxiliary machining parts remain, including the machining of the main oil path oil injection hole, the machining of the main oil path outlet groove and the machining of the auxiliary oil path outlet groove.

(13) The main spray holes are 8 oblique spray type spray holes which are uniformly distributed on the excircle of the head of the nozzle shell along the circumference and are positioned among the eight convex ribs, and in the example, the central line of the main spray holes and the central line of the head form an included angle of 48 degrees. The tail end of the main spray hole is communicated with a main oil way inner cavity formed by the inner ring of the oil collecting cavity and the inner molded surface of the head part of the nozzle shell, and high-pressure fuel oil is injected into the main oil way inner cavity through the main oil way and then is sprayed out of the main spray hole.

The main spray hole is small in diameter and is an oblique-jet type small hole, the clamp is influenced by a special structure of the shell, the design difficulty of the clamp is high, the drill bit is easy to break in the clamp machining process, the drill bit is difficult to take out when being broken inside the shell, the broken drill bit can be removed only by electric machining, and parts are easy to scrap. And the actual processing position of the drill deviates from the theoretical position under the comprehensive action of a plurality of factors in the drilling process, such as the manufacturing error of a clamp, the clamping error of a part, the precision error of the drill and the like. Therefore, the alloy can not be obtained by adopting a mechanical processing method after comprehensive consideration, and the electric spark processing is directly adopted. The electric spark machining is a machining method which utilizes electric energy to remove redundant metal materials, is widely applied after years of development, basically has no macroscopic stress in the machining process, can realize one-step forming machining on parts with complex structures, has certain guarantee on machining precision, and can meet the machining requirements of aviation products.

The schematic processing is shown in fig. 22. Because a remelted layer is left on the hole wall after the electric spark machining, which has great influence on the working performance of the nozzle, the remelted layer must be removed through fine machining, in the embodiment, the hole diameter phi 0.53 is taken as an example for explanation, the actual size meets the flow standard, a certain margin is left at the moment, the flow out-of-tolerance caused by the overlarge one-time hole diameter machining is prevented, and the hole diameter is machined to phi 0.4 by adopting the electric spark.

After the electromachining is completed, reaming must be performed with a reamer to ensure the pore size while removing the remelted layer. In the actual processing process, no phi 0.4 reamer is used, and a phi 0.4 drill bit is directly used for reaming. Because the drill bit with the diameter of phi 0.4 is small in diameter and poor in toughness, the pliers are completely dependent on the skill level of an operator in the machining process, and the phenomenon of cutting can occur when the drill bit is slightly stressed unevenly, so that care must be taken in the machining process. During field machining, an operator directly holds the part by hand, the hole after electric spark machining is led into a rotary phi 0.4 drill bit, the aim of reaming is achieved through up-and-down reciprocating movement, and the requirement on the stability of the operator for manually holding the part is high.

After the reaming of the drill bit with the diameter of phi 0.4 is finished, the drill bits with the diameters of phi 0.45, phi 0.48 and phi 0.5 are sequentially adopted, the operation steps are repeated, the final size of the hole is slowly approached, finally, the polishing rod is used for carrying out micro-polishing to improve the luminosity of the hole wall, and the flow of the nozzle is ensured to be qualified. If the drill bit is broken off in the shell in the machining process, electric sparks are needed to open the blocked small holes. Therefore, the process of machining the main spray hole by the method is very troublesome, the machining difficulty is high, and no better machining method can replace the main spray hole at present.

(15) The main oil way outlet groove is positioned at the main oil way outlet, the sunken part of the hole wall of the inner hole of the head part is hidden, the surrounding structure is complex, and the interference phenomenon can occur by adopting a common processing method. The design allows for electro-machining and allows for a remelted layer. Therefore, the main oil way outlet groove is machined by adopting electric spark, all sizes of the main oil way outlet groove are ensured by the formed electrode, and the size of the main oil way outlet groove completely depends on the precision of the electrode.

The electric spark machining has the advantages of high machining efficiency, stable machining process and high qualification rate, and has the defect that a remelted layer of 0.03-0.05 is left on the machined surface, so that the electric spark machining is completely suitable for machining the outlet groove of the main oil way. The schematic processing is shown in fig. 23.

Similarly, the auxiliary oil way outlet groove is machined by adopting electric spark machining, and the positioning and clamping mode is the same as that of the main oil way outlet groove.

So far, the main processing technology for processing the nozzle shell with the complex profile by using the bar stock has been completely introduced.

Claims (6)

1. A method for processing a nozzle shell by using a bar stock is characterized in that the bar stock is used as a blank, the blank allowance is roughly removed by adopting a turning method to obtain a rough appearance structure of the nozzle shell, and then the nozzle shell is obtained by finish machining;

the method specifically comprises the following steps: placing the maximum outline dimension of the nozzle shell along the axis of the bar, installing the two-dimensional view model of the nozzle shell into the two-dimensional view model of the bar according to the proportion of 1:1 so as to analyze and determine the part of the bar where the machining allowance is located, and then machining the nozzle shell; turning a mounting plate and an eccentric cylinder for processing and forming a rod part of the nozzle shell on the bar by adopting a turning method, and then drilling a plurality of mounting holes on the mounting plate; positioning by using the lower surface of the mounting plate and the mounting hole, and processing the rod part and the head part of the nozzle shell;

calculating the included angle α 4 between the central line of the rod part and the left side contour line of the rod part and the included angle α 5 between the central line of the rod part and the right side contour line, machining the eccentric cylinder by taking the larger value of the α 4 and the α 5 as a half angle to form a cone, and machining to form the rod part of the nozzle shell;

the processing method of the nozzle shell head comprises the steps of firstly raising a bar by an angle α 6 along the horizontal direction to enable the axis of the head to be in the horizontal direction, roughly cutting the shape of the head by adopting a linear cutting method, processing the rear end face of the head into a plane, and carrying out post positioning by using the plane to carry out subsequent fine processing of the head.

2. A method of machining a nozzle housing from a bar stock as claimed in claim 1 wherein the end face of the bar stock adjacent the mounting plate is provided with a tip hole and a platform coaxial with the eccentric cylinder for clamping and alignment in subsequent operations.

3. The method of claim 1, wherein after the machining of the cone, the cone is cut to a flat surface by a linear cutting method, the remelted layer after the linear cutting is removed, and the allowance on one side of the molded surface of the rod part is removed by a four-axis linkage mode of a milling center to form the rod part of the nozzle shell.

4. The method of claim 1, wherein eight arc-shaped grooves are formed in the drill bit by electro-discharge machining after the outer shape of the nozzle housing head is machined.

5. The method of claim 4, wherein after the arc-shaped groove at the head is machined, the deep-hole drilling machine is used to machine the deep holes of the main oil passage and the deep holes of the auxiliary oil passage, and then the groove at the oil nipple part is milled, the reaming hole is expanded, and the oil inlet hole of the auxiliary oil passage is machined.

6. The method of claim 5, wherein after the machining of the oil inlet hole of the secondary oil passage is completed, the primary nozzle hole is roughly machined by means of electric discharge machining, then reaming is performed by means of a reamer, and the primary oil passage outlet groove and the secondary oil passage outlet groove are machined by means of electric discharge machining.

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