A method and device for ensuring the surface quality and size of non-machined surface of small die forgings

Abstract

The present invention relates to the forging field of non-machined surface precision forgings, and in particular to a method and device for ensuring the surface quality and size of the non-machined surface of a small die forging. The method comprises: using a first formula to calculate the thermal size of the forging based on the non-machined surface size and special tolerance, the first formula is: #imgabs0# where L 热 L is the thermal dimension of forging; 冷 is the forging size; T is the preset upper tolerance; B is the preset lower tolerance; Y is the thermal shrinkage rate of the forging material; according to the hot size of the forging, the hot forging drawing and tooling die are designed.

Description

Technical Field

[0001] The invention relates to the field of forging of non-machined surface precision forgings, and in particular to a method and a device for ensuring the surface quality and size of the non-machined surface of a small die forging. Background Art

[0002] Small die forgings of pipe joints are widely used in supporting facilities of main models in the fields of aviation, aerospace, etc., and are the products of the most advanced main combat aircraft equipped by the Air Force. They have many models, many material grades, short cycles and complex working conditions. This puts forward strict requirements on the delivery timeliness and quality stability of small die forgings, especially the surface quality and size of the non-machined surface of small forgings. Strict tolerance requirements cause continuous changes in design dimensions and repeated die repairs in actual production, slow production and delivery efficiency, and surface quality problems (mainly non-machined surface damage removal, grinding, etc.) seriously reduce the first inspection pass rate of forgings. Therefore, the traditional hot dimension design and forging process can no longer meet the actual needs. Summary of the invention

[0003] The purpose of the present invention is to improve the size qualification rate and surface quality of the non-machined surface of small die forgings such as pipe joints.

[0004] To solve this technical problem, the technical solution of the present invention is:

[0005] A method for ensuring the surface quality and size of a non-machined surface of a small die forging, comprising:

[0006] The first formula is used to calculate the thermal dimensions of forgings based on the non-machined surface dimensions and special tolerances. The first formula is:

[0007]

[0008] Among them, L 热 L is the thermal dimension of forging; 冷 is the size of the forging; T is the preset upper tolerance; B is the preset lower tolerance; Y is the thermal shrinkage rate of the forging material;

[0009] According to the hot dimensions of forgings, design hot forging drawings and tooling dies.

[0010] Further, according to the thermal dimensions of the forging, a hot forging drawing and a tooling die are designed, and the method further comprises:

[0011] Determine the heating system of the forging according to the forging material and blanking specifications, which includes the forging temperature and heating time;

[0012] Determine the heat treatment system of the forging according to the forging material and delivery status;

[0013] Use the designed tooling and die to forge according to the heating system of the forging;

[0014] The forgings are heat treated according to the heat treatment system of the forgings.

[0015] Carry out physical and chemical tests according to preset product requirements.

[0016] Furthermore, the forging adopts "two-fire forming + trimming and defect removal between fires".

[0017] Further, the forging is performed using the designed tooling die according to the heating system of the forging, including:

[0018] First fire: flatten the bar material, and the flattening height is calculated according to the deformation requirement of the forging material; then use the tooling die to pre-forge to obtain the pre-forged part;

[0019] Remove the remaining burrs of pre-forged parts;

[0020] Grind and polish the surface defects of pre-forged parts after deburring;

[0021] Second firing: Use the tooling die to final forge the pre-forged parts after grinding and polishing to obtain the final forgings.

[0022] The remaining burrs of the final forging are removed to obtain the forging.

[0023] Furthermore, a pre-forging amount of ~2mm should be left in the first fire.

[0024] Furthermore, in the second fire, the vertical dimension is close, that is, 0 underpressure.

[0025] A device for ensuring the surface quality and size of a non-machined surface of a small die forging, comprising:

[0026] The calculation unit is used to calculate the thermal size of the forging using a first formula based on the non-machined surface size and the special tolerance. The first formula is:

[0027]

[0028] Among them, L 热 L is the thermal dimension of forging; 冷 is the size of the forging; T is the preset upper tolerance; B is the preset lower tolerance; Y is the thermal shrinkage rate of the forging material;

[0029] The design unit is used to design hot forging drawings and tooling dies according to the hot dimensions of forgings.

[0030] Furthermore, the device also includes:

[0031] A first determining unit is used to determine a heating system of the forging according to the forging material and blanking specifications, wherein the heating system includes a forging temperature and a heating time;

[0032] A second determination unit is used to determine a heat treatment system for the forging according to the material and delivery status of the forging;

[0033] The forging unit is used to forge according to the heating system of the forging using the designed tooling die;

[0034] The heat treatment unit is used to perform heat treatment on the forging according to the heat treatment system of the forging.

[0035] The physical and chemical testing unit is used to perform physical and chemical tests according to preset product requirements.

[0036] The beneficial effects of the present invention are as follows: the present invention calculates the thermal dimensions according to Formula 1 in the original thermal dimension design and forging process of small-die forgings such as pipe joints, and optimizes "one-fire forming" to "two-fire forming + trimming and damage removal between fires", so that the non-machined surface dimensions and quality of small-die forgings are effectively guaranteed, the forgings have high dimensional accuracy, can meet the dimensional requirements of high-precision forgings, especially special tolerances, reduce the number of grinding times and mold rework, reduce the forging resistance of the mold, and achieve a one-time inspection pass rate of up to 100%, thereby achieving the purpose of improving the timeliness of delivery and quality stability of small-die forgings such as pipe joints, and providing a new selection path for the die forging production of small-die forgings such as pipe joints. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of a three-way pipe joint;

[0038] Figure 2 is a cross-sectional view of a three-way pipe joint;

[0039] Figure 3 Schematic diagram of flattening the bar;

[0040] Figure 4 This is the pre-forging swing diagram. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0042] The original non-machined surface dimensions are guaranteed by trial machining and repeated die repair, especially the height dimensions of the wrench table need to be controlled by precision pressing equipment later (the wrench openings of a certain type of aircraft are all deadlocked, and the wrench table will not meet the use requirements if it exceeds the tolerance). The non-machined surface dimension requirements are met by optimizing the special tolerance design; at the same time, based on the original traditional bar material one-time forging and non-machined surface damage removal after forging, the surface quality is improved by optimizing the forging process. The specific technical solution is as follows:

[0043] 1) Considering the tolerance zone fit and special tolerance, use formula 1 to calculate the size of the hot forging, and design the hot forging drawing and tooling die.

[0044]

[0045] Among them, L 热 ——hot dimension of forging; L 冷 ——Forging size; T——upper tolerance; B——lower tolerance; Y——thermal shrinkage rate of forging material.

[0046] 2) Forging: The forging temperature, heating time, equipment and parameters, transfer time and cooling method shall be carried out according to the requirements of the corresponding alloy (steel parts, aluminum parts, titanium alloy parts, etc.).

[0047] First fire: Flatten the bar, and the flattening height is calculated according to the corresponding alloy deformation requirements. The purpose of flattening is to enable the blank to better cover the mold cavity during pre-forging to avoid damage; then pre-forging is carried out, and a ~2mm underpressure should be left for pre-forging.

[0048] Trimming: Use laser trimming machine or trimming die to remove the residual burrs of forgings, so as to facilitate the die to be close to ensure the vertical size of forgings during final forging, reduce the forging resistance of the die, and increase the life of the die;

[0049] Visual inspection and polishing of defects: After pre-forging, the surface defects of the pre-forged parts need to be polished and repaired.

[0050] Second fire: After visual inspection and defect repair, the pre-forged parts are final forged, and the second fire is used to make the vertical dimensions close (i.e. the underpressure is 0).

[0051] Secondary trimming: Use a laser trimming machine or trimming die to remove the remaining burrs of the forging.

[0052] 3) Heat treatment: Heat treatment shall be carried out according to the alloy heat treatment system required by the product.

[0053] 4)Physical and chemical: Carry out physical and chemical tests according to product requirements.

[0054] Example

[0055] The specific implementation is described below in conjunction with embodiments.

[0056] Small die forgings of standard three-way pipe joints for a certain type of aircraft (see Figure 1-2 ), the forging material is 1Cr18Ni9Ti, the forging pipe diameter and wrench table are non-machined surfaces, and the heat treatment process is solid solution. The length tolerance not specified in the drawing is According to relevant information, the thermal shrinkage rate of 1Cr18Ni9Ti material is 1.012.

[0057] 1) Design hot forging drawing and tooling die: Use formula 1 to calculate the size of the hot forging. (Lhot is the hot dimension of the forging, Lforged is the forging dimension, T is the upper tolerance, B is the lower tolerance, and Y is the thermal shrinkage rate), taking the thickness dimension of the wrench table as an example: The length dimension 23 can also be calculated using formula 1:

[0058] 2) Forging:

[0059] Cutting: Φ24×36;

[0060] First fire:

[0061] Heating temperature: 1050±10℃, heating time: 10~15min, equipment: 400T / 1000T CNC electric screw press, transfer time ≤10s, cooling method: air cooling.

[0062] Flatten the bar to 12.5±0.5mm (see Figure 3 ), the flattening height is calculated according to the 50% maximum deformation, and then pre-forging is carried out. The swing diagram is shown in Figure 4 , pre-forging needs to leave 2mm underpressure (that is, the thickness of the control wrench table is controlled to be 14).

[0063] Edge trimming: Use laser trimming machine to remove residual burrs of forgings: +0~+1, local tolerance is allowed;

[0064] Visual inspection and polishing of defects: After pre-forging and trimming, surface defects of pre-forged parts and residual burrs after trimming need to be polished and repaired.

[0065] Second fire:

[0066] Heating temperature: 1050±10℃, heating time: 10~15min, equipment: 400T / 1000T CNC electric screw press, transfer time ≤10s, cooling method: air cooling.

[0067] After visual inspection and defect repair, the pre-forged parts are final forged, and the vertical dimensions are matched in the second fire (i.e. the underpressure is 0).

[0068] Secondary trimming: Use a laser trimming machine to remove the remaining burrs of the forging.

[0069] 3) Heat treatment: Solution treatment: 1080±10℃ / 60±6min, cool to below 50℃ with argon blower, then air cool out of the furnace.

[0070] 4)Physical and chemical: Conduct low-magnification physical and chemical tests according to product requirements.

[0071] The 1Cr18Ni9Ti three-way pipe joint small die forgings forged according to the above scheme have low-multiple structure and qualified hardness, all dimensions are within the tolerance range, and the size qualification rate is 100%; after final forging, the forgings do not need to be damaged, and the surfaces are all forged original surfaces, which can meet the strict surface quality requirements of non-machined surfaces. To this end, the tolerance design and die forging method of the pipe joint of the present invention can effectively ensure the timely delivery and quality stability of small die forgings, reduce the die forging manufacturing cost of small die forgings of pipe joints, and meet the assembly requirements of aircraft parts.

[0072] The present invention optimizes the tolerance design and forging process on the basis of the original thermal dimension design and forging process, thereby improving the surface quality of the non-machined surface of the small die forging, and the size meets the requirements of the drawing, greatly improving the first-time qualified rate of forgings, and meeting the special dimension tolerance and surface quality requirements of the non-machined surface of the small die forging, and providing a new selection path for the tolerance design and die forging process of small die forgings.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the field can easily think of various equivalent modifications or substitutions within the technical scope disclosed by the present invention, and these modifications or substitutions should all be covered within the protection scope of the present invention.

Claims

1. A method for ensuring the surface quality and size of the non-machined surface of small die forgings. It is characterized in that include: The first formula is used to calculate the thermal dimensions of forgings based on the non-machined surface dimensions and special tolerances. The first formula is: ； Among them, L 热 L is the thermal dimension of forging; 冷 is the size of the forging; T is the preset upper tolerance; B is the preset lower tolerance; Y is the thermal shrinkage rate of the forging material; According to the hot dimensions of forgings, design hot forging drawings and tooling dies; Determine the heating system of the forging according to the forging material and blanking specifications, which includes the forging temperature and heating time; Determine the heat treatment system of the forging according to the forging material and delivery status; Use the designed tooling and die to forge according to the heating system of the forging; Perform heat treatment on forgings according to the heat treatment system of the forgings; Conduct physical and chemical tests according to preset product requirements; Forging adopts "two-fire forming + trimming and scratch removal between fires"; Use the designed tooling and die to forge according to the heating system of the forging, including: First fire: flatten the bar material, and the flattening height is calculated according to the deformation requirement of the forging material; then use the tooling die to pre-forge to obtain the pre-forged part; remove the residual burrs of the pre-forged part; grind and polish the surface defects of the pre-forged part after burring; Second fire: Use the tooling die to final forge the pre-forged parts after grinding and polishing to obtain the final forgings; Removing the remaining burrs of the final forging to obtain the forging; In the first fire, pre-forging needs to leave ~2mm underpressure; In the second fire, the vertical dimension was close to the target, with 0 underpressure.

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