阅读说明：本技术 一种随形冷却模具的复合增材制造方法 (Composite additive manufacturing method of conformal cooling mold ) 是由 赵宇辉 王志国 赵吉宾 高元 聂长武 于 2018-06-08 设计创作，主要内容包括：本发明公开了一种随形冷却模具的复合增材制造方法,属于增材制造领域。本发明在复杂空腔结构制造过程中,采用管材作为支撑条件,首先在锻造基材上数控加工与冷却管路外径相同的圆弧形状并开坡口,将管材放置于槽内并进行焊接定位和固定；然后采用高效率电弧堆焊的方式,沿着与管材轴向垂直方向摆动增材制造中间层材料；最终在堆焊层数控铣削厚的表面采用激光同步送粉工艺成形致密无缺陷的硬化层。本发明采用管材定位支撑方式,可以实现含流道结构的不变位姿直接成形,在大尺寸中间层材料增材制造过程采用堆焊工艺,可以显著提升增材速率。(The invention discloses a composite additive manufacturing method of a conformal cooling mold, and belongs to the field of additive manufacturing. In the manufacturing process of the complex cavity structure, a pipe is used as a supporting condition, firstly, an arc shape with the same outer diameter as that of a cooling pipeline is processed on a forging base material in a numerical control mode, a groove is formed, and the pipe is placed in the groove and is welded, positioned and fixed; then, swinging the material increase to manufacture an intermediate layer material along the direction vertical to the axial direction of the pipe in a high-efficiency arc surfacing mode; finally, a compact and defect-free hardened layer is formed on the numerically-controlled milling thick surface of the surfacing layer by adopting a laser synchronous powder feeding process. The invention adopts a pipe positioning support mode, can realize the direct forming of the structure containing the flow channel without changing the pose, adopts a surfacing welding process in the material increase manufacturing process of a large-size intermediate layer material, and can obviously improve the material increase rate.)

1. A composite additive manufacturing method of a conformal cooling mold is characterized by comprising the following steps: the conformal cooling mold comprises a cooling flow channel, a groove which is matched with the cooling flow channel in structure is firstly processed on a mold base material in the manufacturing process, a supporting pipe is placed in the groove bottom, then the rest space in the groove is filled by adopting a surfacing welding process, and finally a hardened layer is prepared on the surface of the base material by adopting a laser cladding process.

2. The composite additive manufacturing method of the conformal cooling mold according to claim 1, wherein: the method comprises the following steps:

(1) Processing a base material: designing a cooling runner structure according to the requirements of a mold, processing a groove which is adaptive to the cooling runner structure on a base material, and ensuring that the bottom surface of the processed groove is completely attached to the outer wall of a supporting tube; grooves are respectively arranged on two sides of the groove;

(2) Welding and positioning: placing the supporting tube into the bottom of the groove and fixing the supporting tube by using a clamp, and then welding and fixing the two sides of the tube and the base material;

(3) Surfacing and filling: filling the space in the groove layer by adopting a powder plasma arc surfacing process until the groove is completely filled; adopting a powder material with good deformability as a filling material;

(4) The laser cladding process comprises the following steps: and milling and flattening the surface of the surfacing layer, and preparing a hardened layer on the surface subjected to numerical control milling by adopting a synchronous powder feeding type laser cladding process.

3. The composite additive manufacturing method of the conformal cooling mold according to claim 1, wherein: the mould base material is plastic mould steel, and the supporting tube is a stainless steel tube or a copper tube.

4. the composite additive manufacturing method of the conformal cooling mold according to claim 2, wherein: in the welding and positioning process in the step (2), a welding mode of splicing multiple sections of pipelines is required for complex pipelines.

5. The composite additive manufacturing method of the conformal cooling mold according to claim 2, wherein: in the surfacing filling, swinging along the direction vertical to the axial direction of the support tube to perform additive manufacturing so as to fill the milled part; the bottom layer is filled with small energy input and powder feeding amount, and the heat input and the powder feeding amount are gradually increased along with the increase of the cladding height.

6. The composite additive manufacturing method of a conformal cooling mold according to claim 2 or 5, wherein: in the surfacing filling step (3), the current is 80-200A, the distance between the end face of the contact tube and the workpiece is 8-12mm, and the powder conveying speed is 10-40 g/min; the powdered material used for the filling was 316L stainless steel or inconel 625.

7. The composite additive manufacturing method of the conformal cooling mold according to claim 2, wherein: in the surfacing filling step (3), the melting of the matrix at the groove position is ensured as much as possible in the surfacing process, the problem of poor combination is avoided, the starting point of the processing is a base material or a formed part, and the penetration of the pipe in the welding process is ensured as little as possible; the scan path planning should minimize the time of continuous accumulation on the outer wall of the tubing.

8. The composite additive manufacturing method of the conformal cooling mold according to claim 2, wherein: in the synchronous powder feeding type laser cladding process in the step (4), the laser power is 1400-2000W, the powder feeding speed is 7-15g/min, the scanning speed is 3-6mm/s, the lap joint rate is more than 50%, and inert atmosphere protection is adopted.

9. The composite additive manufacturing method of the conformal cooling mold according to claim 2, wherein: in the step (4), the hardened layer is made of a high-hardness material.

Technical Field

The invention belongs to the technical field of additive manufacturing, and particularly relates to a composite additive manufacturing method of a conformal cooling mold.

Background

The current powder feeding type additive manufacturing is mainly applied to near net size forming of solid parts such as large-scale structures and thin-wall structures, the material utilization rate is relatively high, the machining allowance after forming is small, the process flexibility is high, the application is gradually wide in the fields of aerospace and the like, and compared with powder laying type additive manufacturing, the powder feeding type additive manufacturing can achieve forming of complex cavity structures. Powder fed additive manufacturing processes often fail to achieve unsupported overhanging surfaces.

At present, the mold structure represented by an injection mold has extremely high requirements on surface quality and cooling performance, and the temperature of the mold must be adjusted to achieve high-efficiency production and obtain an injection molded product with excellent performance. The mold temperature directly affects the quality and production efficiency of the injection molded article and is controlled and regulated properly mainly by the cooling system of the mold. The traditional cooling water channel can only be processed into a simple straight hole, and when the shape of an injection molding piece is complex, the cooling effect is poor, and the deformation of the part is large. Conformal cooling is a good solution for cooling plastic products with high efficiency in a minimum cycle time.

the shape following cooling mode is different from the traditional cooling mode in that the shape of the cooling water channel changes along with the appearance of the injection molding product and is not linear any more. The cooling channel well solves the problem that the distance between the traditional cooling water channel and the surface of the die cavity is inconsistent, so that the injection molding product can be uniformly cooled, and the cooling efficiency is higher.

Through the shape following cooling die for additive manufacturing, the processing efficiency of the injection die can be greatly improved, but the surface precision of the die manufactured by the additive manufacturing is not high, and the required surface precision is obtained through the finish machining, the polishing treatment and the like in the later stage. At present, foreign researchers at foreign countries also propose that the powder feeding type additive manufacturing technology can be used for directly forming a cavity structure of a die by adopting a complex displacement technology, but the cavity structure manufactured by adopting the method is poor in shape regularity of the upper arm of the cavity and unsmooth in inner wall.

disclosure of Invention

aiming at the defects in the prior art, the invention aims to provide a composite additive manufacturing method of a conformal cooling mold, which sequentially adopts a numerical control milling process, a welding process, a build-up welding process and a laser synchronous powder feeding process for additive compounding to realize additive manufacturing of a cooling channel in the conformal cooling mold.

in order to achieve the purpose, the technical scheme adopted by the invention is as follows:

A composite additive manufacturing method of a conformal cooling mold comprises a cooling flow channel, wherein in the manufacturing process, a groove matched with the structure of the cooling flow channel is firstly processed on a mold base material, a supporting pipe is placed in the bottom of the groove, then the rest space in the groove is filled by adopting a surfacing process, and finally a hardened layer is prepared on the surface of the base material by a laser cladding process. The method specifically comprises the following steps:

(1) Processing a base material: designing a cooling runner structure according to the requirements of a mold, processing a groove which is adaptive to the cooling runner structure on a base material, and ensuring that the bottom surface of the processed groove is completely attached to the outer wall of a supporting tube; grooves are respectively arranged on two sides of the groove; the bevel angle is enough, so that the collision between the front end of a welding gun subjected to surfacing welding and a part in an automatic scanning process is avoided; the mould base material is plastic mould steel, and the supporting tube is a stainless steel tube or a copper tube.

(2) welding and positioning: placing the supporting tube into the bottom of the groove and fixing the supporting tube by using a clamp, and then welding and fixing the two sides of the tube and the base material;

(3) Surfacing and filling: filling the space in the groove layer by adopting a powder plasma arc surfacing process until the groove is completely filled; adopting a powder material with good deformability as a filling material;

(4) The laser cladding process comprises the following steps: milling and flattening the surface of the surfacing layer, preparing a hardened layer on the surface subjected to numerical control milling by adopting a synchronous powder feeding type laser cladding process, and ensuring the fusion quality of the profile material by adopting a mode of high energy input, low scanning speed and high lap joint rate.

in the welding and positioning process in the step (2), a welding mode of splicing multiple sections of pipelines is required for complex pipelines. The separation of the pipe and the matrix is avoided as much as possible in the welding process, and the welding function is to prevent the pipe from warping and deforming in the subsequent surfacing process;

In the surfacing filling in the step (3), the material is added and manufactured by swinging along the direction vertical to the axial direction of the support tube so as to fill the milled part; the bottom layer is filled with small energy input and powder feeding amount, and the heat input and the powder feeding amount are gradually increased along with the increase of the cladding height.

In the surfacing filling in the step (3), the current is 80-200A, the distance between the end face of the contact tube and the workpiece is 8-12mm, and the powder conveying speed is 10-40 g/min; the powdered material used for the filling was 316L stainless steel or inconel 625.

In the surfacing filling in the step (3), the melting of the matrix at the position of the groove is ensured as much as possible in the surfacing process, the problems of poor combination and the like are avoided, the starting point of the processing is a base material or a formed part, and the penetration of the pipe in the welding process is ensured as little as possible; the scan path planning should minimize the time of continuous accumulation on the outer wall of the tubing.

In the synchronous powder feeding type laser cladding process in the step (4), the laser power is 1400-2000W, the powder feeding speed is 7-15g/min, the scanning speed is 3-6mm/s, the lap joint rate is more than 50%, the complete melting of powder in the material increase process is ensured, and the inert atmosphere is adopted for protection; the hardened layer is a high hardness material.

The invention has the advantages and beneficial effects that:

1. In the manufacturing process of the complex cavity structure, a pipe is used as a supporting condition, firstly, an arc shape with the same outer diameter as that of a cooling pipeline is processed on a forging base material in a numerical control mode, a groove is formed, and the pipe is placed in the groove and is welded, positioned and fixed; then, swinging the material increase to manufacture an intermediate layer material along the direction vertical to the axial direction of the pipe in a high-efficiency arc surfacing mode; and finally, forming a compact and defect-free hardened layer on the surface of the surfacing layer subjected to numerical control milling by adopting a laser synchronous powder feeding process. The invention adopts a pipe positioning support mode, can realize the direct forming of the structure containing the flow channel without changing the pose, adopts a surfacing welding process in the material increase manufacturing process of a large-size intermediate layer material, and can obviously improve the material increase rate.

2. The invention adopts the plasma beam surfacing and synchronous powder feeding laser cladding composite additive manufacturing method to realize the direct manufacture of the cavity structure (cooling runner) in the die; the electric arc additive manufacturing has the characteristics of high heat input, large heat source radius, short-range flow of metal melt and the like, can realize the surfacing filling of a cavity structure (middle-layer material) with high speed and high utilization rate of powder materials, and obviously improves the cost and efficiency compared with a laser synchronous powder feeding technology. But the deposition quality of the surfacing is lower than the quality of the laser synchronous powder feeding additive. Therefore, the invention adopts laser synchronous powder feeding additive manufacturing to realize high-quality forming of the surface layer of the die.

3. According to the invention, plasma beam surfacing and synchronous powder feeding and material increasing pipe burying are adopted, so that the free arrangement of materials such as stainless steel, copper pipes and the like on a base body can be realized, and the cooling performance of the die can be obviously improved.

4. The technology can provide an important technical approach for the free design and manufacture of the die with high surface cooling performance requirements.

Drawings

FIG. 1 is a schematic process flow diagram of the present invention;

FIG. 2 is a view of a groove and bevel for processing a substrate; wherein: (a) a single tube cavity structure; (b) the double-tube cavity structure.

Detailed Description

in order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in detail with reference to the accompanying drawings and specific embodiments.