CN109531157B - Full-size machining method for centrifugal ventilator - Google Patents

Abstract

The invention belongs to the manufacturing technology of engines, and particularly relates to a full-size machining method of a centrifugal ventilator. The full-size machining method of the centrifugal ventilator comprises the steps of firstly turning the appearance of a blank, making a technological reference, roughly machining and milling a radial plate of the centrifugal ventilator by using a milling cutter, then finely milling the radial plate, releasing internal stress in a stress relieving mode, machining an internal spline by using gear shaping, and finely turning the appearance of the centrifugal ventilator. Compared with the traditional casting method, the full-size machining method of the centrifugal ventilator can effectively improve the product precision, improve the dynamic balance performance and ensure the strength performance of the product by machining, and meanwhile, the machining method is simple and has higher efficiency.

Description

Full-size machining method for centrifugal ventilator

Technical Field

The invention belongs to the manufacturing technology of engines, and particularly relates to a full-size machining method of a centrifugal ventilator.

Background

The existing centrifugal ventilator parts are processed by adopting a casting process, and the adopted process route is as follows: the manufacturing process of the impeller part comprises the following steps: blank casting → post-casting treatment [ preliminary examination printing, cleaning, sand blowing, secondary examination, sand blowing, fluoroscopy, X-ray examination, tertiary examination, sand blowing, heat treatment, kerosene soaking, sand blowing, final examination ] → turning (rough machining) → dynamic balance (no weight removal, dynamic balance magnitude and direction marking) → turning (finish machining, eccentric compensation calculated according to the dynamic balance magnitude) → tooth insertion → fluorescence (cold machining and blank defect inspection) → dynamic balance → fluorescence (defect due to weight removal) → size measurement → chromic acid anodization.

In the whole process, the casting of the part has a large influence on the dynamic balance, and meanwhile, the process after the dynamic balance has a large influence on the dynamic balance, so that the dynamic unbalance of the part is influenced finally, and the total unbalance of the dynamic balance of the original product is not more than 10 g.mm.

Disclosure of Invention

The purpose of the invention is: the full-size machining method can effectively enhance the strength of the centrifugal ventilator and ensure the dynamic balance quality.

The technical scheme of the invention is as follows: a full-size machining method for a centrifugal ventilator comprises the steps of firstly turning the appearance of a blank, making a technological reference, roughly machining and milling a radial plate of the centrifugal ventilator by using a milling cutter, then finely milling the radial plate, releasing stress in a stress relieving mode, machining an internal spline by using gear shaping, and finely turning the appearance of the centrifugal ventilator.

And during rough machining, preliminarily machining the spoke plate and the root part switching arc R4 by using a flat-end milling cutter with the diameter of phi 10 mm.

During rough machining, the root transfer arc R4 is machined in a boring mode.

During fine machining, a ball-end milling cutter with the diameter of 8mm is adopted to perform fine milling on the transfer arc R4 and the side face of the spoke plate, so that smooth transfer is guaranteed.

And the end surface of the centrifugal ventilator is subjected to finish milling by adopting a flat-end milling cutter with the diameter of phi 8 mm.

The cutting edge of the milling cutter is at least 30% longer than the cutting depth.

The diameter of the milling cutter body is 10% larger than that of the cutting edge.

And before finish machining, the allowance of the single surface is 0.8-1.2 mm.

And reinforcing ribs are added at the root parts of the internal splines.

By adding mandrels with different tolerances and adjusting pads, the assembling clearance of the centrifugal ventilator is eliminated, and the dynamic balance quality is ensured.

The specific process of the full-scale machining method of the centrifugal ventilator comprises the following steps:

step 1: firstly, turning the appearance and the inner hole of a blank, and making a process reference to be used as a reference for subsequent machining;

wherein the length of the straight edge of the sharp edge chamfer on the side surface of the rib plate is 0.2-0.4 mm, the angle is 45 degrees, and the bulge is removed.

Step 2: solid solution and artificial aging are carried out, the hardness HB of the blank is more than or equal to 80, so as to ensure good subsequent cutting performance;

and step 3: drilling a process hole on the side surface of the blank cylinder: the diameter phi is 6 +/-0.03 mm, the hole depth is 4.5 +/-0.1 mm, and the hole depth is used for matching with a tool during the subsequent milling to determine the angular direction;

and 4, step 4: and roughly machining the radial plate of the centrifugal ventilator.

And (3) cutting the radial plates layer by layer from outside to inside by adopting a flat-end milling cutter with the diameter of phi 10mm, adjusting the angle of a cutter shaft, and primarily milling the transfer arc R4 at the root part of each radial plate, wherein the allowance of a single surface is 0.4-0.5 mm.

And 5: finish milling radials

And a ball-end milling cutter with the diameter of 8mm is adopted to finish mill the transfer arc R4 and the side surface of the spoke plate, so that smooth transfer is ensured.

And the end face of the centrifugal ventilator is subjected to finish milling by adopting a flat-end milling cutter with the diameter of phi 8 mm.

Processing to 55mm of hub diameter, controlling the thickness of a web plate to be 2.5 +/-0.3 mm, taking an inner hole as a reference, and controlling the final symmetry degree of the pattern to be 0.7, but performing chromic acid anodization on the product finally, considering that the web plate is thin and has certain deformation, and controlling the symmetry degree of the web plate to the inner hole to be within 0.5;

step 6: stress relief: so as to release stress and reduce subsequent processing deformation. The equipment is an air circulation furnace, the parts are flatly placed in the furnace, the heat preservation temperature is 150 +/-5 ℃, the heat preservation time is 2-3 hours, and the cooling mode is air cooling.

Before finish machining, the allowance of the single surface is 0.8-1.2 mm to reduce deformation

And 7: finish turning of the appearance of the centrifugal ventilator: the verticality of the two end faces to the reference inner hole is controlled within 0.01, and the parallelism of the two end faces is controlled within 0.03, so that the precision requirement of subsequent dynamic balance is met.

And 8: inserting an internal spline: the inner hole on the other side of the spline of the centrifugal ventilator is used as a reference for positioning, the bottom hole before aligning the spline is within 0.01 of tolerance, after gear shaping is completed, a measurement list is provided for the first piece and the tail piece of a tooth root R0.3 +/-0.2, and each piece is at least measured at 4 positions which are uniformly distributed so as to meet the 6H precision requirement of the spline standard GB/T3478.1;

and step 9: dynamic balance calibration: the inner hole phi 44.1 +/-0.016 mm of the centrifugal ventilator is formed, the tolerance +0.016 is matched with the core shaft in two stages according to 0.008, the core shafts with different tolerances and the adjusting pad are added, the assembly clearance of the centrifugal ventilator is eliminated, and the dynamic balance quality is ensured.

Step 10: the special requirements of the cutter are as follows:

the cutting edge of the milling cutter is at least 30% longer than the cutting depth, so that the cutting force can be reduced, the operation is convenient, and the processing efficiency is improved.

The diameter of the position of the cutter bar of the milling cutter is 10 percent larger than that of the cutting edge, so that the vibration during machining is reduced, and the machining precision is improved.

In addition, during rough machining, the root transfer arc R4 can be subjected to boring rotary machining, which can further improve machining efficiency.

1) And feeding the cutter along the outer diameter, firstly roughly milling to mill a cavity structure, and milling the blade of the part to be machined to be through in order to reduce the stress as much as possible.

2) Firstly, a milling cutter with the diameter of 10mm is adopted for rough machining, and then the specific characteristics of the part are arranged for finish machining. And aiming at the round angle at the joint of the blade and the end face as R4, a milling cutter with the diameter of phi 8mm is adopted on the side face of the blade, and a milling cutter with the diameter of phi 8mm is adopted on the end face of the part for finish milling.

The invention has the technical effects that: compared with the traditional casting method, the full-size machining method of the centrifugal ventilator can effectively improve the product precision, improve the dynamic balance performance and ensure the strength performance of the product by machining, and meanwhile, the machining method is simple and has higher efficiency.

Drawings

FIG. 1 is a schematic view of the construction of a centrifugal ventilator to be treated according to the invention;

FIG. 2 is a cross-sectional view B-B of FIG. 1;

FIG. 3 is a schematic view of an internal spline configuration;

FIG. 4 is a half-sectional view of an internal spline;

wherein, 1-spoke plate, 2-inner cavity and 3-inner spline.

Detailed Description

The invention is further illustrated with reference to the following figures and examples:

referring to fig. 1, the centrifugal ventilator to be treated according to the present invention comprises a web 1, an inner cavity 2, and an inner spline 3. The spoke plate 1 is 12 in number and is uniformly arranged in the inner cavity 2, and the inner spline 3 is arranged on the end face of one side of the inner cavity 2. The tooth shape design tolerance of the internal spline is 0.033, the tooth direction tolerance is 0.012, the unbalance total amount of dynamic balance is not more than 5g.mm, the fillet of the connecting part of the radial plate and the end face is R4, the thickness of the connecting part is 2.5-2.8 mm, and the radial distribution of the radial plate enables the distance between the radial plate and the radial plate to be smaller and smaller, and the distance size of the minimum position is 10.39 mm. In addition, the root part of the internal spline is additionally provided with a layer of rib plate for connection, and the rib plate is in transition connection with the web plate and the end face by a fillet, so that the structure has higher processing difficulty.

The equipment and the tooling of the full-size machining method of the centrifugal ventilator are as follows:

the blade profile of the mechanical centrifugal ventilator is mainly realized by milling, and is divided into rough milling and finish milling. The assembly fixture used at the present stage can meet the requirement of normal use.

A small five-axis machine tool is used.

3 cutters, namely a phi 10mm flat-end milling cutter, a phi 8mm flat-end milling cutter and a phi 8mm ball-end milling cutter are used.

And (3) analyzing the process feasibility:

1) improved process design structure

Three dimensions exist for the transition R between the web and the side wall, namely 12 in total for the front view transition radius R5, 24 in total for R4 in A-A view, and 72 in total for R4 in B-B view.

At present, the root transfer fillet of the centrifugal ventilator is R4, a ball-end milling cutter with the diameter of phi 8mm is used during processing, the probe length is 65mm, the rigidity is not strong, vibration is easy to generate during processing, vibration lines are left on the surface of a part, and the surface roughness of the part is influenced. Through two rounds of process tests on a production field, the phenomena of machining vibration lines and tool marks on the surface of a product are found from the appearance.

Under the feasible condition, if the root part transfer fillet is R5, a ball milling cutter with the diameter of 10mm can be used, the rigidity is greatly improved compared with the ball milling cutter with the diameter of 8mm, the generation of vibration text can be effectively reduced, and the feeding speed is improved.

2) Numerical control tool optimization

At present, three problems mainly exist, and measures are taken aiming at the three problems: firstly, the cutter cutting edge is longer, the rigidity of the cutter that also weakens to a certain extent, secondly the diameter of cutter arbor position will be slightly bigger than cutting edge department, causes the cutter arbor to rub the surface that the part has been processed during processing, influences part surface quality. And thirdly, a rough machining tool used for finish machining, such as a phi 8mm ball end mill, is a finish machining tool with 2 cutting edges at present, coordinates with a cutter manufacturer to customize more than 4 cutting edges, and can greatly improve the quality of a machined surface and the cutting efficiency.

3) Process optimization

At the present stage, the outer diameter of the part in the process is phi 128mm, the final size is phi 122.5mm, and the diameter of the previous process can be reserved by 1mm in consideration of the allowance in the subsequent process, so that the cutting amount of the process is reduced.

4) Program processing mode optimization

The root switching R4 is changed into a boring processing mode from milling cutter layer cutting, each surface processing adopts an oblique line interpolation method, the rotating speed and the feeding are further improved, and the program processing mode is optimized.

5) Dynamic unbalance analysis

Considerations for dynamic balance of the mandrel

The radial fit clearance between the core shaft and the centrifugal ventilator is large;

the radial fit clearance between the mandrel and the adjusting pad is large, the assembling precision is low, and the dynamic unbalance is greatly influenced.

And the sum of the mass of the mandrel and the mass of the adjusting pad is far larger than the mass of the centrifugal ventilator, so that the dynamic balance data of the centrifugal ventilator is greatly influenced.

And fourthly, when the dynamic unbalance of the same centrifugal ventilator is repeatedly measured, the dynamic unbalance of the balance core shaft directly influences the dynamic balance precision requirement of the part.

The implementation process of the full-size machining method of the centrifugal ventilator is as follows:

1) preparing: preparing a bar of centrifugal ventilator to be processed, material 2A70 GB/T3191;

2) processing: processing an inner mounting hole of the centrifugal ventilator to a qualified size, processing an end face and an outer diameter, and roughly and finely milling a radial plate, wherein the maximum parallelism of the processed end face is 0.03mm, and the verticality of the end face to the inner hole is less than 0.01 mm; 3) checking before balancing: before dynamic balancing, the balancing machine HL-1B is checked to ensure that the equipment is in a qualified state, the appearance of the centrifugal ventilator is checked, and the centrifugal ventilator is intact without burrs, defects and cracks and has no defects in surface treatment;

4) part installation and balance: the balance fixture can be arranged on a workbench of a Schecker balance machine HL-1B, the centrifugal ventilator is arranged on the balance tool, the '+' of the balance mandrel is aligned with the '+' of the centrifugal ventilator, the '-' of the balance mandrel is aligned with the '-' of the centrifugal ventilator, and the centrifugal ventilator is assembled with the balance mandrel after the positions are aligned. The initial balance tool 1B362/S10-1008 is used in the initial balance, and the final balance tool 1B362/S10-1007 is used in the final balance;

5) dynamic balance operation: in the whole operation process, the photoelectric head only allows micro adjustment, and does not allow a rotation angle, if the rotation angle is rotated, turnover compensation is required to be carried out again; and setting a 180-degree turnover compensation mode on the balancing machine, starting the balancing machine, operating for the first time, slowly increasing the speed to 1500 rpm, uniformly rotating, and finishing the operation after the indication value is stable.

6) And (3) dynamic balance checking: the residual unbalance of the centrifugal fan is about 5g.mm by using a material removing method, and then the centrifugal fan is turned over by 180 degrees relative to the balance mandrel (namely, "+" of the balance mandrel is aligned with "+" of the centrifugal fan, "-" of the balance mandrel is aligned with "-" of the centrifugal fan, and the scribed lines on the pressing plate are aligned with the scribed lines on the mandrel), so that the residual unbalance is qualified when the residual unbalance is not more than 10g.mm of the specified value.

7) And (5) unloading the centrifugal ventilator on the dynamic balancing machine, and submitting to inspection.

The final result is: the residual unbalance of the centrifugal ventilator is not more than the specified value of 10g.mm, and the form and position tolerance, the dimensional precision and the surface roughness of parts all meet the requirements of design patterns.

1. The centrifugal ventilator is changed from casting to machining, and the material is changed from ZL114A to 2A70, so that the strength is improved;

2. the unilateral spigot positioning of the centrifugal ventilator is changed into bilateral spigot positioning, so that the assembly stability is improved;

3. the fillet at the root of the shoulder of the centrifugal ventilator on the gear shaft of the centrifugal ventilator is reduced, the axial matching area is increased, and the reliability of the product is improved.

4. The modified centrifugal ventilator is additionally provided with reinforcing ribs at the root parts of the splines.

Claims (2)

1. A full-size machining method of a centrifugal ventilator is characterized in that a blank shape is firstly turned, a technological reference is made, a web of the centrifugal ventilator is roughly machined and milled by a milling cutter, then the web is finely milled, an internal stress is released in a stress relieving mode, internal splines are machined by gear shaping, and the centrifugal ventilator shape is finely turned;

the cutting edge of the milling cutter is at least 30 percent longer than the cutting depth, and the diameter of the position of the milling cutter bar is 10 percent larger than the diameter of the cutting edge;

milling through the part blades during rough machining, machining the root transfer arc R4 in a boring mode during rough machining, and machining each surface by adopting a slope interpolation method;

the specific process of the full-scale machining method of the centrifugal ventilator comprises the following steps:

step 1: firstly, turning the appearance and the inner hole of a blank, and making a process reference to be used as a reference for subsequent machining;

wherein the length of the straight edge of the sharp edge chamfer on the side surface of the rib plate is 0.2-0.4 mm, the angle is 45 degrees, and the bulge is removed;

step 2: solid solution and artificial aging are carried out, the hardness HB of the blank is more than or equal to 80, so as to ensure good subsequent cutting performance;

and step 3: drilling a process hole on the side surface of the blank cylinder: the diameter phi is 6 +/-0.03 mm, the hole depth is 4.5 +/-0.1 mm, and the hole depth is used for matching with a tool during the subsequent milling to determine the angular direction;

and 4, step 4: roughly machining a radial plate of the centrifugal ventilator;

adopting a flat-end milling cutter with the diameter of phi 10mm to cut the radial plates layer by layer from outside to inside, then adjusting the angle of a cutter shaft, and primarily milling the transfer arc R4 at the root part of each radial plate, wherein the allowance of a single surface is 0.4-0.5 mm;

and 5: finish milling radials

A ball-end milling cutter with the diameter of phi 8mm is adopted to finish mill the transfer arc R4 and the side surface of the spoke plate, so that smooth transfer is ensured;

the end face of the centrifugal ventilator is subjected to finish milling by adopting a flat-end milling cutter with the diameter of phi 8 mm;

processing to 55mm of hub diameter, controlling the thickness of a web plate to be 2.5 +/-0.3 mm, taking an inner hole as a reference, and controlling the symmetry of the web plate to the inner hole to be within 0.5;

step 6: stress relief: so as to release stress and reduce subsequent processing deformation; the equipment is an air circulation furnace, the parts are flatly placed in the furnace, the heat preservation temperature is 150 +/-5 ℃, the heat preservation time is 2-3 hours, and the cooling mode is air cooling;

before finish machining, the allowance of the single surface is 0.8-1.2 mm, so that deformation is reduced;

and 7: finish turning of the appearance of the centrifugal ventilator: the verticality of the two end faces to the reference inner hole is controlled within 0.01, and the parallelism of the two end faces is controlled within 0.03, so that the precision requirement of subsequent dynamic balance is met;

and 8: inserting an internal spline: the inner hole on the other side of the spline of the centrifugal ventilator is used as a reference for positioning, the bottom hole before aligning the spline is within 0.01 of tolerance, after gear shaping is completed, a measurement list is provided for the first piece and the tail piece of a tooth root R0.3 +/-0.2, and each piece is at least measured at 4 positions which are uniformly distributed so as to meet the 6H precision requirement of the spline standard GB/T3478.1;

and step 9: dynamic balance calibration: the inner hole phi 44.1 +/-0.016 mm of the centrifugal ventilator is formed, the tolerance +0.016 is matched with the core shaft in two stages according to 0.008, the core shafts with different tolerances and the adjusting pad are added, the assembly clearance of the centrifugal ventilator is eliminated, and the dynamic balance quality is ensured.

2. The full-scale machining method for a centrifugal ventilator according to claim 1, wherein a reinforcing rib is added to the root of the internal spline.

Images