CN102699454A - Electrolytic machining system and method for foamed aluminium buffering and energy adsorbing material - Google Patents

Abstract

The invention discloses an electrolytic processing system and method for foamed aluminum buffer energy-absorbing materials, including an electrolytic processing machine tool, which is composed of a processing system, a control system, an electrolyte system and a fixture device, and the foamed aluminum porous material to be processed is firstly fixed. Finally, adjust the distance between the foamed aluminum material and the electrode, and set various processing parameters before electrolytic processing. For porous materials such as aluminum foam, compared with traditional turning, planing and grinding, the technical solution of the present invention overcomes the deformation and destruction of the porous structure during processing.

Description

A system and method for electrolytic processing of foamed aluminum buffer and energy-absorbing material

technical field

The invention relates to the field of electrolytic machining, and more specifically relates to an electrolytic machining system and method for foamed aluminum buffer energy-absorbing materials.

Background technique

Aluminum foam is a light porous metal material with Al or its alloy as the matrix and contains a large number of pores. Its main structural characteristics are large pore size and high porosity. Structural and functional metallic materials. Aluminum foam has the characteristics of small specific gravity, light weight, strong heat resistance, high rigidity, etc., and also has the function of cushioning and energy absorption, and is increasingly valued by various fields such as packaging and transportation, military protection, aviation, and aerospace. Especially as a cushioning and energy-absorbing material, it has been widely used in the cushioning packaging of vulnerable items, the protection of important equipment such as satellites and missiles, and the filling of structures. Compared with other cushioning and energy-absorbing materials, the outstanding advantages of aluminum foam are:

(1) Under the action of small compressive stress, it can produce elastic deformation, so the stress value transmitted to the protected object is very small, which plays a good protective role;

(2) The foamed aluminum can achieve the maximum energy absorption capacity by adjusting the density of the foamed aluminum material;

(3) Aluminum foam does not rebound during the process of absorbing energy;

(4) Aluminum foam is isotropic macroscopically, so its energy absorption capacity has nothing to do with the impact direction.

When subjected to an external impact load, it is easy to deform, with a large amount of deformation and a low level of flow stress. During the compression deformation process, a large amount of work can be consumed, which can be transformed into deformation, collapse, rupture, and cell wall friction of the cells in the structure. The energy dissipated in various forms can effectively absorb the impact energy of the outside world. This characteristic of absorbing a large amount of impact energy at a lower stress level is an ideal material for cushioning energy absorption. In terms of performance, aluminum foam is a lightweight energy-absorbing material for cushioning, but the strength of aluminum foam itself is not high, so it is not suitable for use as a structure for energy-absorbing cushioning alone; the strength of metal hollow tubes is higher than that of aluminum foam, but Its cushioning and energy-absorbing properties are far inferior to foamed aluminum. In order to give full play to the cushioning and energy-absorbing advantages of foamed aluminum itself, the foamed aluminum is filled in the hollow metal tube to obtain a foamed aluminum sandwich structure, which becomes a composite material with better cushioning and energy-absorbing.

At present, the research focus on aluminum foam mainly focuses on its preparation, structure, performance, design, cost reduction, and expansion of its application fields, and rarely involves the machining of aluminum foam. In order to apply aluminum foam to the field of cushioning and energy absorption, it is necessary to process aluminum foam of different shapes and sizes. Due to the special pore structure of aluminum foam, the traditional processing techniques such as turning, planing and grinding lead to serious deformation and destruction of the pore structure on the surface of aluminum foam, so that the processed aluminum foam does not meet the requirements of the subsequent process. For this reason, seeking a new processing method for foamed aluminum is a key problem that needs to be solved urgently in the practical application of foamed aluminum.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art. For porous materials such as aluminum foam, in order to overcome the deformation and destruction of the porous structure during processing, an electrolytic processing system that utilizes metal materials to undergo anodic dissolution in the electrolyte is provided. And methods to obtain special processing methods with dimensional accuracy. Compared with traditional turning, planing and grinding, the most important feature of electrolytic machining is that the machining method is a non-contact machining, which has a wide range of machining and is not limited by the hardness, strength and toughness of the material itself. At the same time, This processing method also has significant advantages such as high productivity and good surface quality, and is especially suitable for processing difficult-to-machine materials.

The purpose of the present invention is achieved through the following technical solutions:

An electrolytic processing system for aluminum foam buffer energy-absorbing materials, including an electrolytic processing machine tool, consisting of a processing system, a control system, an electrolyte system and a fixture device,

The processing system is composed of a processing power supply and a processing electrode. The processing power supply adopts a pulse power supply to provide electric energy for electrolytic processing, and an electrochemical reaction is formed between the processing electrode and the workpiece to be processed for electrolytic processing;

The control system controls the rotation speed of the machine tool, the horizontal and vertical feed speeds of the working electrode during the electrolytic machining process, so as to meet the machining accuracy requirements;

The electrolyte system is composed of a working fluid tank, a working fluid pump, a working fluid circuit and a filter device. The working fluid tank is used to store the electrolyte, and the working fluid pump supplies the electrolyte to the machining gap. The electrolyte is recovered through the working fluid circuit, and at the same time Equipped with a working fluid filter to eliminate the influence of impurities;

The clamp device is used to clamp the workpiece to be processed, and realize the required movement of the workpiece according to the processing requirements of the workpiece.

The basic requirements that the entire electrolytic machining system needs to meet include: (1) The electrolytic machining machine tool should have sufficient rigidity and necessary corrosion resistance; (2) The control system must have a reliable short-circuit protection device to ensure machining accuracy; (3) Electrolytic machining The liquid system requires stable liquid supply and the ability to filter and process electrolysis products.

The electrolytic machining machine tool is refitted from an ordinary machine tool. In order to easily maintain the precision and rigidity of the original machine tool and shorten the refitting time, the main structure of the original machine tool should be kept as much as possible during the refitting process. The maximum processing length of the electrolytic machining machine tool is 700mm, and the workpiece clamping and fixing devices of the original machine tool are maintained, mainly for the clamping of cylindrical foamed aluminum. During the processing, the foamed aluminum is driven to rotate at a low speed to ensure the roundness of the foamed aluminum processing. Spend. The tool used in traditional processing is replaced with a processing electrode, and the electrolytic machining of the workpiece is realized through the electrochemical reaction between the electrode and the workpiece, and the distance between the electrode and the workpiece is adjusted (after the workpiece is fixed and installed, the horizontal and vertical directions of the electrode are controlled by the control system. Feed speed, the range of horizontal feed speed is 0.01~1.08mm/min, the range of longitudinal feed speed is 0.04~2.16mm/min), voltage and current (for example, pulse power supply is used, the rated input power of the power supply is 60KVA, the working The output current range of the power supply is 0~2000A) to realize the control of electrolytic processing. An electrochemical reaction is formed between the workpiece and the processing electrode, and the electrolyte environment is established between the two through the electrolyte system, and the circulation of the electrolyte is realized through the working fluid pump, and the filter device is used to avoid the influence of impurities, and the electrolyte is supplied to the pump. The power is 3.2KW, and the power of the electrolyte filter pump is 0.35KW.

A method for electrolytic processing of foamed aluminum buffer energy-absorbing materials, carried out according to the following steps:

(1) Fix the aluminum foam porous material to be processed;

(2) Before processing starts, adjust the distance between the foamed aluminum material and the electrode, and set various processing parameters;

(3) Start processing. After the foamed aluminum is processed, stop the equipment and clean the processed foamed aluminum workpiece.

During electrolytic machining, the corresponding machining parameters are as follows:

(1) Current density

The current density is an important processing parameter in the electrolytic machining process, and the magnitude of the current density directly affects the processing efficiency and the surface roughness of the material. In the actual processing process, the current density should not be too large. When the current density value exceeds a certain upper limit, the inter-electrode heat and erosion products will increase too much. If the pump pressure and electrolyte flow rate are not increased at the same time, it will cause processing. Abnormal phenomena such as evaporation and boiling of the electrolyte in the area will lead to faults such as short circuits, thereby interrupting the processing process. Therefore, for the electrolytic machining process of aluminum foam porous material, it is determined that the suitable current density range of foam aluminum porous material is 25~30A/cm ² .

(2) Processing voltage

In the process of electrolytic machining, the machining voltage refers to the potential difference between the anode of the workpiece and the cathode of the tool, which is the energy source for establishing the electric field between the anode of the workpiece and the cathode of the workpiece to enable electrolytic machining. The determination of the processing voltage value needs to be comprehensively selected according to the processed material, shape, size and selected current density. For the electrolytic processing of foamed aluminum, the processing voltage is generally 18~20V.

(3) Initial processing clearance

The difference in the initial machining gap given before ECM will affect the transition process to reach the equilibrium gap during ECM, thus affecting the machining accuracy. For porous aluminum foam materials, the initial machining gap is determined to be 1.0-2mm.

(4) Feed speed

Summary of the electrolytic machining process, the determination of the electrolytic feed rate is mainly based on the area of the material to be processed and the selected initial machining gap, and the capacity of the voltage also needs to be considered comprehensively. For electrolytic processing of porous aluminum foam materials, the range of transverse feed speed should be controlled at 0.03~0.08mm/min, and the range of longitudinal feed speed should be controlled at 0.07~1.50mm/min.

(5) Choice of electrolyte

Electrolyte is the carrier of anodic dissolution in the process of electrolytic machining, and the correct selection of electrolyte is the basic condition for realizing electrolytic machining. In the process of electrolytic machining, the main functions of the electrolyte are: 1) as a conductive medium to transmit current; 2) to perform electrochemical reactions under the action of an electric field, so that the anode dissolution can proceed smoothly and in a controlled manner; The electrolysis products and heat generated in the battery are taken away, which plays the role of renewal and cooling. Comprehensively considering the specific application conditions of various electrolytes, the electrolytic processing process of porous aluminum foam materials is determined. The selected electrolyte is NaNO ₃ aqueous solution with a concentration of 25wt%~30wt%.

(6) Electrolyte pressure

High-voltage, high-speed electrolyte flow is the prerequisite for high current density. In order to reasonably match the determined current density, initial processing gap and other parameters, and take away the electrolytic products and heat generated during the processing, it is necessary to adjust the electrolyte pressure to change the flow rate and flow of the electrolyte. After theoretical calculation and a large number of process tests, it is determined that the pressure of the electrolyte is 0.2~0.4MPa during the electrolytic processing of foamed aluminum.

Traditional material processing methods mainly include turning, milling, planing and grinding. Since foamed aluminum is a porous material composed of metal matrix frames interlaced in space, there are a large number of holes scattered inside the matrix. These holes are in a cellular structure and surrounded by metal skeletons, and these holes are separated from each other and have different shapes and sizes. Therefore, when the traditional machining method is used to process the aluminum foam porous material, it is very easy to cause serious collapse of the surface pore structure of the foam aluminum porous material, and the entire structure is damaged. For example, when processing foamed aluminum porous materials by milling. Since the milling process is mainly based on the rotation of the milling cutter, the cutting process of the workpiece as a feed motion. During this process, the cutting force exerted by the milling cutter on the workpiece changes periodically, because the workpiece will inevitably vibrate during the milling process, which makes it easier to damage the porous structure of aluminum foam. In addition, during the planing process, there is no feed movement during the cutting process, and the cutting is carried out intermittently. When the tool cuts into and cuts off the workpiece, there is an impact load, which causes shock and vibration during the planing process, and it is easy to cause foam Collapse of aluminum pore structure.

Compared with traditional processing methods, the electrolytic processing of the technical solution of the present invention has significant advantages in the processing of foamed aluminum. Because electrolytic machining is a non-contact special processing method that uses the principle of anodic dissolution of metals in electrolytes to shape workpieces. The basic process of the processing method is as follows: during the processing, a small gap is maintained between the electrolytic electrode and the workpiece, and the electrolyte flows through the gap. Apply low-voltage direct current to the gap, according to Faraday's law, the workpiece begins to dissolve, the dissolved product is discharged from the processing area by the flowing electrolyte, and the electrolytic electrode is fed to the workpiece at a constant speed to keep the processing gap constant. With the continuation of the processing process, the shape of the workpiece will approximately replicate the shape of the electrolytic electrode, and the external dimensions of the workpiece required for processing will be obtained. Because this method has significant advantages such as wide processing range, high productivity, good surface quality, and no loss of electrolytic electrodes, it is especially suitable for processing difficult-to-machine materials, so as to overcome the deformation and destruction of porous structures during processing.

Description of drawings

Figure 1 is a schematic diagram of the composition of the electrolytic machining system of the present invention, wherein 1 is a fixture, 2 is an aluminum foam workpiece, 3 is a plug, 4 is a guide rail, and 5 is a working electrode (ie, an electrolytic electrode).

Detailed ways

The technical solutions of the present invention will be further described below in conjunction with specific embodiments.

The electrolytic machining machine tool used is the electrolytic machining special machine tool PHECMC 6132-750 of Dongguan Huidie Automation Technology Co., Ltd. The processing electrode (ie electrolysis electrode) used is made of stainless steel 1Cr18Ni9Ti, and the two sides of the electrode are pasted with epoxy resin for insulation. The foamed aluminum porous material used is prepared by a melt foaming method with a grade of ZL111 aluminum alloy as a base material. The density of the aluminum foam is 0.65×10 ³ kg/m ³ , and its main chemical composition is shown in Table 1.

Table 1 Chemical composition of ZL111 aluminum alloy (wt%)

Si Mg Ti Mn Cu Al 8.0~10.0 0.4~0.6 0.1~0.35 0.1~0.35 1.3~1.8 Surplus

According to the implementation parameters in the table below, the electrolytic processing of foamed aluminum is carried out. The foamed aluminum workpiece does not produce deformation and damage of the porous structure at the end, and basically maintains the shape before processing.

The present invention has been described as an example above, and it should be noted that, without departing from the core of the present invention, any simple deformation, modification or other equivalent replacements that can be made by those skilled in the art without creative labor all fall within the scope of this invention. protection scope of the invention.

Claims (5)

1. the Electrolyzed Processing system of a foamed aluminium buffering energy-absorbing material comprises electrolytic machine tool, it is characterized in that, constitute by system of processing, control system, electrolyte system and grip device,

Said system of processing is made up of processing power source and machined electrode, and said processing power source adopts the pulse power, for Electrolyzed Processing provides electric energy, forms electrochemical reaction between said machined electrode and the workpiece to be processed and carries out Electrolyzed Processing;

In the said control system control electrochemical machining process, the horizontal and vertical feed speed of the rotary speed of lathe, working electrode, thus reach the required precision of processing;

Said electrolyte system is made up of working liquid container, work liquid pump, working solution loop and filter; Working liquid container is used to store electrolyte, and the work liquid pump provides electrolyte to machining gap, reclaims electrolyte through the working solution loop; While configuration effort liquid filter is with the influence of despumation;

Said grip device is used for clamping workpiece to be processed, and according to the processing request of workpiece, realizes the needed motion of workpiece.

2. the Electrolyzed Processing system of a kind of foamed aluminium buffering energy-absorbing material according to claim 1 is characterized in that, said grip device drives the foamed aluminium low speed rotation for the clamping of cylindrical foam aluminium in process, to guarantee the circularity of foamed aluminium processing.

3. the electrochemical machining method of a foamed aluminium buffering energy-absorbing material is characterized in that, carries out according to following step:

(1) foamed aluminium porous material to be processed is fixed;

(2) before the processing beginning, regulate foamed aluminium material and interelectrode distance, and each machined parameters is set;

(3) begin processing, treat that foamed aluminium processes after, arrestment, to processing the foamed aluminium workpiece clean.

4. the electrochemical machining method of a kind of foamed aluminium buffering energy-absorbing material according to claim 3 is characterized in that, in electrochemical machining process, its corresponding machined parameters is following: current density range is at 25 ~ 30A/cm ²Machining voltage is 18 ~ 20V; The initial manufacture gap is 1.0-2mm; The traverse feed velocity interval should be controlled at 0.03 ~ 0.08mm/s, and the length feed velocity interval should be controlled at 0.07 ~ 1.50mm/min; Electrolyte is that concentration is the NaNO of 25wt% ~ 30wt% ₃The aqueous solution; The pressure of electrolyte is 0.2 ~ 0.4MPa.

5. electrochemical machining method is in the application of foamed aluminium buffering energy-absorbing material processing field.

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