阅读说明：本技术 一种解决压铸活塞销孔平行度不合格的工艺 (Process for solving problem of unqualified parallelism of die-casting piston pin hole ) 是由 祝文明 李志国 常帅 于 2020-11-16 设计创作，主要内容包括：本发明提供了一种解决压铸活塞销孔平行度不合格的工艺,包含有如下步骤：(1)铸造压铸机生产出来的压铸活塞毛坯,放入抛丸机内,进行抛丸处理,抛丸时间为20分钟；(2)压铸活塞毛坯抛丸后进行热处理,在井式炉内加热至225±5°,并保温8小时；(3)将热处理完的活塞毛坯进行加工生产,在加工环槽过程中,顶住活塞毛坯内腔,加工出顶部工艺定位台,在加工活塞销孔时,以顶部工艺定位台为基准,并和固定夹具密切配合,用气缸压持活塞内腔顶部,使活塞销孔及其周边部位不受外力影响；(4)在加工顶部平面时,销子拉住环槽进行加工,使活塞销孔不受力,使用本工艺生产出来的压铸活塞销孔平行度在2um以下,完全符合标准要求的4.5um以下。(The invention provides a process for solving the problem of unqualified parallelism of a die-casting piston pin hole, which comprises the following steps of: (1) casting a die-casting piston blank produced by a die-casting machine, and putting the die-casting piston blank into a shot blasting machine for shot blasting treatment, wherein the shot blasting time is 20 minutes; (2) performing heat treatment on the die-cast piston blank after shot blasting, heating the die-cast piston blank to 225 +/-5 ℃ in a pit furnace, and preserving heat for 8 hours; (3) the piston blank after heat treatment is processed and produced, the piston blank inner cavity is propped against in the process of processing the ring groove, a top process positioning table is processed, when a piston pin hole is processed, the top process positioning table is used as a reference and is closely matched with a fixing clamp, and the top of the piston inner cavity is pressed by a cylinder, so that the piston pin hole and the peripheral part thereof are not influenced by external force; (4) when the top plane is processed, the pin pulls the ring groove to process, so that the piston pin hole is not stressed, and the parallelism of the die-casting piston pin hole produced by the process is below 2um and below 4.5um which completely meets the standard requirement.)

1. The process for solving the problem of unqualified parallelism of the pin hole of the die-casting piston is characterized by comprising the following steps of:

casting a die-casting piston blank produced by a die-casting machine, and putting the die-casting piston blank into a shot blasting machine for shot blasting treatment, wherein the shot blasting time is 20 minutes;

performing heat treatment on the die-cast piston blank after shot blasting, heating the die-cast piston blank to 225 +/-5 ℃ in a pit furnace, and preserving heat for 8 hours;

the piston blank after heat treatment is processed and produced, the piston blank inner cavity is propped against in the process of processing the ring groove, a top process positioning table is processed, when a piston pin hole is processed, the top process positioning table is used as a reference and is closely matched with a fixing clamp, and the top of the piston inner cavity is pressed by a cylinder, so that the piston pin hole and the peripheral part thereof are not influenced by external force;

when the top plane is machined, the pin pulls the ring groove to be machined, so that the piston pin hole is not stressed, and the phenomenon of unqualified parallelism caused by stress of the piston pin hole is eliminated.

2. The process for solving the problem of unqualified parallelism of the pin hole of the die-casting piston as claimed in claim 1, wherein the shot blasting treatment uses stainless steel shots with the diameter of 0.2 mm.

Technical Field

The invention belongs to the technical field of piston processing, and particularly relates to a process for solving the problem of unqualified parallelism of a die-casting piston pin hole.

Background

The pressure casting piston is more and more on small engines, such as a mower, a chain saw and the like, engines produced by enterprises such as Steyr, Fuji, TTI and the like of world well-known brands are used in batches, the small engines are small in size, large in power, long in operation time and large in work load, the engines are required to have good working performance, the core part piston of the corresponding engine is required to be more excellent and involves the problems of strength, durability, emission and the like of the piston, the molten aluminum has higher strength after being formed into the piston by die casting under the pressure of 400 tons, the parallelism of a corresponding piston pin hole is not good, certain interference and space exist between the piston pin and the connecting rod, the durability is deteriorated, the emission does not reach the standard, therefore, the die casting piston is a product with strict requirements on various indexes, particularly on emission, fatigue resistance and power,

the share of the products reaches 30% at present, but the flatness of the piston pin hole is difficult to meet the technical requirements, and the piston produced by the existing production process has fewer qualified products, cannot meet the requirements of the existing orders, suffers from customer complaints and also causes great loss of profits of the company.

Disclosure of Invention

In order to solve the technical problems, the invention provides a process for solving the problem that the parallelism of the die-casting piston pin hole is unqualified, and the parallelism of the die-casting piston pin hole produced by the process is below 2um and below 4.5um which completely meets the standard requirement.

The technical scheme adopted by the invention is as follows: the process for solving the problem of unqualified parallelism of the pin hole of the die-casting piston is characterized by comprising the following steps of:

(1) casting a die-casting piston blank produced by a die-casting machine, putting the die-casting piston blank into a shot blasting machine, wherein the shot blasting machine is a Q326 crawler-type shot blasting machine, performing shot blasting treatment by using stainless steel shots with the diameter of 0.2mm, the stainless steel shots can avoid surface oxidation of the die-casting piston blank, simultaneously removing edge burrs, increasing the surface hardness, enhancing the tensile strength, and the shot blasting time is 20 minutes,

(2) and (3) performing heat treatment on the piston blank subjected to shot blasting, heating the piston blank to 225 +/-5 ℃ in a pit furnace, and preserving heat for 8 hours to ensure that the piston blank has uniform texture and fine metallographic structure, and simultaneously eliminating the internal stress of the piston blank and reducing the influence of the internal stress on the parallelism of pin holes in the process of processing the piston pin holes.

(3) The piston blank after heat treatment is processed and produced, the prior process that a top is directly propped against the top is changed, the new process props against the inner cavity of the piston blank in the process of processing the ring groove to process a top process positioning table, when a piston pin hole is processed, the top process positioning table is taken as a reference and is closely matched with a fixed clamp, and the top of the piston inner cavity is pressed by a cylinder, so that the piston pin hole and the peripheral parts thereof are not influenced by external force.

(4) When the top plane is processed, the prior process that the pin is pulled by the cylinder and the pin pulls the piston pin hole is changed, and the method that the pin directly pulls the ring groove is adopted, so that the piston pin hole is not stressed, and the phenomenon of unqualified parallelism caused by stress of the piston pin hole is eliminated.

Furthermore, stainless steel shots with the diameter of 0.2mm are used in the shot blasting treatment,

the piston hardness is enabled to meet the technical requirement of HBW100-140 through heat treatment, in the volume stability test, after the piston is heated to 250 +/-5 ℃ and is kept warm for 6 hours, the volume stability of the piston is measured to be 0-0.014%, and the technical requirement is less than or equal to 0.025%;

the parallelism of the piston pin holes of the product processed by the process is detected to be below 2um, the standard requirement is below 5um, and the technical requirement is completely met.

Drawings

FIG. 1 illustrates a tooling used in the prior art of the present invention;

FIG. 2 is a sectional view in the direction of FIG. 1A-A;

FIG. 3 shows a tooling used in the original process;

FIG. 4 is a sectional view in the direction of FIG. 3A-A;

the reference numbers in the figures illustrate: 1-piston 2-ring groove clamping piece 3-pulling pin 4-outer sleeve 5-piston pin hole 6-pulling pin hole 7-inner working shaft.

Detailed Description

The following examples further describe embodiments of the present invention in detail.

Example 1:

the process for solving the problem of unqualified parallelism of the pin hole of the die-casting piston is characterized by comprising the following steps of:

(1) casting a die-casting piston blank produced by a die-casting machine, putting the die-casting piston blank into a shot blasting machine, wherein the shot blasting machine is a Q326 crawler-type shot blasting machine, performing shot blasting treatment by using stainless steel shots with the diameter of 0.2mm, the stainless steel shots can avoid surface oxidation of the die-casting piston blank, simultaneously removing edge burrs, increasing the surface hardness, enhancing the tensile strength, and the shot blasting time is 20 minutes,

(2) and (3) performing heat treatment on the piston blank subjected to shot blasting, heating the piston blank to 225 +/-5 ℃ in a pit furnace, and preserving heat for 8 hours to ensure that the piston blank has uniform texture and fine metallographic structure, and simultaneously eliminating the internal stress of the piston blank and reducing the influence of the internal stress on the parallelism of pin holes in the process of processing the piston pin holes.

(3) The piston blank after heat treatment is processed and produced, the prior process that a top is directly propped against the top is changed, the new process props against the inner cavity of the piston blank in the process of processing the ring groove to process a top process positioning table, when a piston pin hole is processed, the top process positioning table is taken as a reference and is closely matched with a fixed clamp, and the top of the piston inner cavity is pressed by a cylinder, so that the piston pin hole and the peripheral parts thereof are not influenced by external force.

(4) When the top plane is processed, the prior process that the pin is pulled by the cylinder and the pin pulls the piston pin hole is changed, and the method that the pin directly pulls the ring groove is adopted, so that the piston pin hole is not stressed, and the phenomenon of unqualified parallelism caused by stress of the piston pin hole is eliminated.

The original process comprises the following steps:

1) the die casting machine produces a piston blank and carries out heat treatment, the heat treatment temperature is 200 ℃, the time is 9 hours, and the internal stress of the piston blank cannot be eliminated;

2) the tool supports the inner cavity of the piston blank, the center supports the top of the piston blank, the outer circle and the annular groove are machined, and when the center supports the top, the center gives an indirect force to the piston pin hole;

3) the cylinder presses the top of the piston to process a piston pin hole, and the pin hole indirectly bears the pressure from the cylinder;

4) when the top of the piston is machined, the pull pin is pulled by the cylinder, the piston pin hole is pulled by the pull pin, and the pulling force is not lower than 0.6MPa, so that the pin hole has certain deformation;

the comparison of the parameters of the die-casting piston processed by the process of the invention and the original processing technique is shown in table 1, and the table shows that the volume stability and the pin hole parallelism of the new technique are obviously better than the original processing technique.

TABLE 1 comparison of die-cast piston parameters processed using the original and inventive processes