RU2802609C1 - Device for electric erosion piercing of holes with electrode tool - Google Patents

Abstract

FIELD: machining.

SUBSTANCE: electric erosion machining of conductive materials used for piercing holes in a part, a product of any surface complexity from various materials that fully or partially conduct electric current. The device contains an electrode-tool, a system for supplying a working fluid to the processing zone, a current generator, a control unit and a device for developing a control program. The device is equipped with a multi-axis manipulation robot with a spherical coordinate system and a system for collecting and removing waste fluid and electric erosion products washed out of the treatment area during hole piercing, configured to interact with the fluid supply system to the treatment area to obtain a closed working fluid recirculation system. At the output link of the robot, an executive body is rigidly fixed, made with the possibility of fixing the electrode-tool, made in the form of a hollow or solid, single or composite electrode-tool.

EFFECT: expanding the design and functionality of the device.

1 cl, 8 dwg

Description

The invention relates to electrical discharge machining of conductive materials and can be used in the oil, chemical, mining, and metallurgical industries for making holes in a workpiece, a product of any surface complexity made of various materials that fully or limitedly conduct electric current (metals, polymer composite materials).

A device is known for making holes using the non-contact electroerosive method of a metal workpiece (Technology of structural materials. Under the direction of G.A. Preis. Published by "Vissha School", Kiev, 1984, pp. 320-321, Fig. VI-91), containing the base on which the machine and a bath with a dielectric liquid in it are located. A device is installed in the bath, on which the metal workpiece being processed is placed, connected to a current source and serving as an anode. The current source is a pulse generator. An electrode-tool, which is the cathode, is connected to the DC pulse generator through the clamps. The electrode-tool is fixed to the machine stand with a chuck. The electrode tool is placed above the surface of the metal workpiece with a gap.

Disadvantages of the device:

• The device is functionally and structurally limited, due to the fact that the electrode-tool is limited in movement and is designed to pierce one hole. Processing of complex-profile parts is impossible.

• The size of the workpiece is limited by the dimensions of the bath. The device is not designed for the use of hollow and composite electrode tools, as well as for multi-axis movement of the electrode tool during processing, which reduces its productivity and functionality.

A device for electroerosive piercing of holes is known (patent No. 2730321, published on August 21, 2020, Bulletin No. 24), containing a pulse current generator to which a tool electrode (EI) (-) and a workpiece electrode (ED) ( +). The working fluid is supplied to the treatment zone from the nozzles through a flexible pipeline. Transformer oil is used as the working fluid. The surface to be treated is covered with a metal template sheet with a through hole.

Disadvantages of the device:

• The depth of the hole to be machined is limited.

• The device is functionally limited due to the fact that only glass or carbon fiber plastics are processed.

• The unit for supplying, discharging, and collecting the working fluid is placed in a container with this liquid, which worsens its properties due to a constant increase in the concentration of electrical erosion products that are removed from the processing zone into the same container.

• The electrode-tool is fixed in the holder strictly vertically and makes only reciprocating movements. Processing surfaces with complex profiles is possible only due to the shaping parameters of the electrode tool. This limits the functionality and design capabilities of the device.

The closest device for the same purpose to the claimed invention in terms of the set of features is a device for electrical discharge machining of holes with a hollow electrode tool (patent No. 2687525, MPK V23N 7/32, published 02.20.2019, bulletin No. 5), containing a CNC machine, a hollow electrode-tool mounted on the stand of a CNC machine, a current generator that supplies voltage to the workpiece (+) and to the electrode-tool (-), a high-pressure hydraulic line connected to the cavity of the electrode-tool to supply working fluid to the surface being processed , a low-pressure hydraulic line for supplying working fluid and a pneumatic air supply line, united by a tee. The tee introduces a mixture of air and liquid into the cavity of the part being processed by the electrode tool. Contains an adjusting throttle that regulates the pressure in the internal cavity of the workpiece, a control unit for the system for supplying working fluid to the cavity of the electrode tool and to the cavity of the workpiece, as well as air to the cavity of the workpiece. The control unit and the system of interelectrode gap sensors during the process of electrical discharge machining of a hole with an electrode tool in the workpiece sends a signal to the computer that controls the electromagnetic valves for supplying working fluid and air. This device is accepted as a prototype.

Disadvantages of the device adopted as a prototype:

• The device is complicated by the presence of a cavity in the workpiece, the supply of working fluid through two channels, and the formation of an air-working fluid mixture;

• The device is structurally limited. The device is designed to process only hollow products;

• The device is limited to strictly vertical reciprocating movement of the electrode tool;

• The device is designed to pierce only one hole per installation. Piercing multiple holes is possible only when the workpiece is moved relative to the electrode tool;

• The device does not imply the presence of a system for recirculating the working fluid and its purification during processing.

The objective of the invention is to expand the design and functionality of the device.

The problem was solved due to the fact that the known device for electrical discharge piercing of a hole with an electrode-tool in a part made of a material that fully or limitedly conducts electric current, containing an electrode-tool, a system for supplying working fluid in the form of transformer oil to the processing zone, a current generator, supplying electrical impulses to the workpiece (+) and to the electrode tool (-), the control unit and the device for developing the control program, according to the invention, is equipped with a multi-axis manipulation robot with a spherical coordinate system connected to the control unit and the device for developing the control program, and a system for collecting and discharging waste liquid and electroerosion products washed out of the processing zone during the hole piercing process, designed to interact with the liquid supply system into the processing zone to obtain a closed system for recirculating the working fluid, while the executive body is rigidly fixed to the output link of the multi-axis manipulation robot , made with the possibility of multi-axis movement specified by the control program, and containing a hollow rod connected to the current pulse generator (-) with a quick-release chuck installed on it for securing the electrode-tool, made in the form of a hollow or solid, single or composite electrode-tool, system supply of working fluid to the processing zone includes a container with working fluid, a fine filter at the outlet of the container, a pump, a pressure regulator of the working fluid, connected through a flexible pipeline, with the pipeline connected to a hollow rod for supplying working fluid into the cavity of the rod in a quick-release chuck electrode-tool and into the processing zone, and the system for collecting and discharging waste liquid and electrical erosion products washed out of the processing zone during the piercing process contains holes connected by a pipeline with a coarse filter installed in it, a bath and the mentioned container with working fluid, and in The bathtub has a table for placing the workpiece on it with a gap.

A comparative analysis of the proposed technical solution with the prototype showed that the device is novel and has an inventive step, because is unknown and does not clearly follow from the prior art related to electrical discharge machining of holes. The device is industrially applicable because can be used in many industries that require the task of making holes, especially in complex-profile products.

Unlike the prototype, the problem of fixing the moment when the electrode-tool leaves the part is solved by installing the workpiece on a table with a gap. This greatly simplified the device and expanded its design capabilities, expanding the range of processed products.

The use of transformer oil as a working fluid allows you to optimize the process of electrical discharge machining of holes. As studies have shown, during electrical discharge machining in a high-temperature dielectric liquid, carbon deposits do not form in the interelectrode space, which reduces the quality of the hole and the part as a whole. The use of oil as a working fluid during electrical discharge machining of polymer composite materials makes it possible to expand the technological capabilities of the device, because The composite is processed without burning out its components with a low melting point.

Unlike the prototype, the device can use hollow or solid single and composite electrodes-tools, depending on the tasks assigned and the material of the workpiece. This ensures the expansion of technological capabilities. Productivity increases. It becomes possible to process not only metals and their alloys, but also materials with limited electrical conductivity. The functionality of the device is expanded.

Unlike the prototype, the system for supplying working fluid to the electrode tool and to the processing zone allows it to be delivered from a container through a flexible pipeline with the ability to regulate the pressure of the working fluid. This ensures continuous supply of liquid with a given pressure to the treatment zone. Pressure regulation allows for turbulent movement of the working fluid in the processing zone, which significantly accelerates the collection and removal of processing products from the interelectrode gap and intensifies the cooling process. The constant supply of working fluid, the ability to regulate the pressure and speed of its supply depending on the material of the workpiece and electroerosion products in the form of sludge of large and small fractions, provides a significant expansion of the design and functionality of the device. Fixing the moment the electrode-tool exits the material of the part in the presence of a gap between the part and the table prevents contact of the electrode-tool with the table, thereby maintaining the integrity of the table and avoiding unnecessary wear of the electrode-tool.

Unlike the prototype, the presence of a system for collecting and discharging waste liquid and electroerosion products washed out of the processing zone during the piercing process allows for recirculation of the working fluid without its loss, which allows expanding the functionality of the device.

Unlike the prototype, the device uses a quick-release chuck to secure the electrode tool. This ensures quick change of the tool electrode.

The multi-axis manipulation robot with a spherical coordinate system used allows for multidirectional complex movements of the device's executive body. It becomes possible to pierce holes in complex-profile parts and products.

Unlike the prototype, the device allows you to process any complex-profile elements of products from any conductive or limited conductive materials, functionally expanding the capabilities of the device due to the multi-axis functioning of the robot, controlled by a system for supplying working fluid to the localized processing zone, the presence of an executive body with a set of various electrode tools, the presence of a recirculation and filtration system for working fluid, acting towards the implementation of a single plan in solving the problem.

The proposed device is illustrated by the drawings shown in Fig. 1-8.

In fig. 1 shows the general diagram of the device.

In fig. 2 – kinematic diagram of a multi-axis manipulation robot.

In fig. 3 – diagram of the device’s executive body.

In fig. 4-6 – options for electrode tools: hollow, solid, composite, respectively.

In fig. 7 – diagram of the working fluid recirculation system in the form of transformer oil in the device.

In fig. 8 – diagram of a multi-axis manipulation robot in the process of piercing holes in a processed part with a complex profile.

The device contains a multi-axis manipulation robot 1 (Fig. 1) with a spherical coordinate system, consisting of a fixed base 2 and moving links 3-8 (Fig. 2), connected to a control unit 9 and a device (PC) for developing a control program 10 (Fig. .1). A device 11 is rigidly attached to the output link 8 of the robot for fixing the executive body 12 (Fig. 3) on the robot 1 for flashing a hole in the workpiece 13 installed on the table 14 with a gap 15 (Fig. 1). The executive body 12 includes a hollow rod 16, a keyless keyless chuck 17 (Fig. 3) and an electrode tool 18.

The electrode-tool 18 is fixed in the lower part of the quick-release chuck 17, in the upper part of the quick-release chuck 17 a hollow rod 16 is rigidly installed. The electrode-tool 18 can be hollow (Fig. 4) or solid (Fig. 5), single or composite (Fig. 6) and has the specified hole-shaping parameters and properties.

The executive body 12 has the possibility of multi-axis movement specified by the control program.

The device includes a recirculation system 19 (Fig. 1) of working fluid in the form of transformer oil, consisting of systems for supplying, collecting and discharging fluid.

The working fluid supply system in the form of transformer oil contains: a container 20 with a working fluid 21 in it, a fine filter 22 of the working fluid at the outlet of the tank, a pump 23, a fluid pressure regulator 24, a flexible pipeline 25 (Fig. 7) for supplying the working fluid into the cavity 26 of the rod 16, into the cavity 27, 28 and 29 of the screw 30 of the quick-release chuck 17, to the electrode tool 18 (Fig. 3) and into the processing zone.

The system for collecting and discharging waste liquid 31 and electroerosion products washed out of the processing zone during the drilling process contains: a bath 32, a pipeline 33, a coarse filter 34 installed in the pipeline 33 (Fig. 7). Bath 32 is made in the form of a container of variable cross-section. The upper part of the bath 32 is designed to minimize emissions of working fluid beyond its boundaries.

In the bath 32 for collecting waste liquid, a table 14 is installed to place the workpiece 13 on it (Fig. 1). The workpiece 12 is a part made of continuous conductive or limited conductive material. Transformer oil was used as the working fluid.

The pulse current generator 35 supplies current to the workpiece 13 (+) and to the hollow rod 16 (-) of the actuator 12 (Fig. 1, 3).

The device works as follows.

The device is being assembled. The workpiece 13 of any size within the size of the bath 32 and any configuration made of fully or partially electrically conductive material (metal, composite, etc.) is placed on the table 14 with a gap 15 (Fig. 1).

The multi-axis manipulation robot 1 is turned on (Figs. 1, 2). Robot 1, according to the commands of the control program coming from the PC 10 through the control unit 9, brings the electrode-tool 18 to the workpiece 13 (Fig. 1, 2, 8). The material (copper, graphite, composite material such as a pseudo-alloy of the copper-colloidal graphite system, etc.) of the electrode-tool is selected based on the assigned tasks and the material of the workpiece 13. The supply of working fluid 21 is turned on.

Working fluid 21 (transformer oil 1800 GOST 982-8) is continuously supplied to the processing zone from tank 20 by pump 23. In the case of flashing with a single or composite solid electrode tool 18 (Fig. 4, 6), the working fluid 21 from the hollow rod is supplied to the cartridge due to the presence of a cavity 26 in the rod 16 and cavities 27, 28 and 29 in the screw 30 of the cartridge 17 (Fig. 3 ). In the case of piercing with a hollow electrode tool (Fig. 5), the working fluid 21 from the hollow rod is supplied to the chuck due to the presence of cavity 26 in the rod 16 and cavities 27, 28 and 29 in the screw 30 of the chuck 17 and into the cavity of the electrode tool 18 (Fig. 3). The working fluid is supplied under pressure, ensuring its turbulent movement, localized in the processing zone. The turbulent movement of the working fluid accelerates the process of removing sludge - products of electrical erosion - from the processing zone.

The control program command connects the workpiece 13 (+) to the current generator 34 (Fig. 1). A pulse current (-) is supplied to the electrode-tool 18 through a hollow rod 16 and a quick-release chuck 17 attached to it (Fig. 1, 3). The command also sets the current parameters: current strength (I), voltage (U), pulse duration (Ton).

According to the commands of the control program, the actuator 12 is moved relative to the surface of the workpiece 13 by the robot 1 (Fig. 8) and electrical discharge piercing of holes, which involves changing the shape, size, roughness and surface properties of the workpiece 13 under the influence of electrical discharges as a result of electrical erosion for due to the local concentration of a large concentration of energy in the interelectrode space.

Thanks to the gap 15 between the table 14 and the workpiece 13, the unhindered exit of the electrode tool 18 from the workpiece 13 is ensured and the moment of completion of machining the hole or holes is clearly recorded.

During the flashing process, the spent working fluid with sludge 31 enters a bath of variable cross-section 32 (Fig. 7). The liquid is cleaned from large fractions of sludge particles in coarse filter 34. Through pipeline 33, waste liquid 31 enters the previously named container 20 of the working fluid supply system 21. From small fractions of sludge particles, the working fluid is cleaned in fine filter 22. After cleaning, pump 23 supplies clean working fluid 21 in the form of transformer oil through a flexible pipeline 25 into the hollow rod 16 of the cartridge 17, into the electrode-tool 18 and into the processing zone. Due to the interaction of the elements of the fluid supply system to the electrode-tool 18 and to the processing zone with the system for collecting, discharging and purifying waste fluid, a closed system for recirculating the working fluid is obtained in the device.

The advantage of the proposed device compared to the prototype:

• For the first time, electrical discharge machining of holes in the workpiece was performed in a device using a multi-axis manipulative universal robot, which significantly expands the design and technological capabilities of the device.

• The device for electrical discharge machining has an environmentally relevant closed system for supplying, collecting, discharging and purifying the working fluid.

• The device allows you to process any complex-profile elements of products from any conductive or limited conductive materials, functionally expanding the capabilities of the device due to the presence of multi-axis movement of the robot, a controlled system for localized supply of working fluid to the processing zone, the presence of an actuator, a variety of electrodes-tools, the presence of a recirculation system and filtration of the working fluid, acting together towards the implementation of a single plan in solving the problem.

Claims (1)

A device for electroerosive piercing of a hole with an electrode-tool in a part made of a material that fully or limitedly conducts electric current, containing an electrode-tool, a system for supplying working fluid in the form of transformer oil to the processing zone, a current generator that supplies electrical pulses to the workpiece (+) and on an electrode-tool (-), a control unit and a device for developing a control program, characterized in that it is equipped with a multi-axis manipulation robot with a spherical coordinate system connected to the control unit and a device for developing a control program, and a system for collecting and discharging waste fluid and products of electrical erosion washed out from the processing zone during the process of piercing a hole, made with the ability to interact with the liquid supply system into the processing zone to obtain a closed system for recirculating the working fluid, while the output link of the multi-axis manipulation robot is rigidly fixed to the actuator, made with the possibility of multi-axis movement, specified by the control program, and containing a hollow rod connected to the current pulse generator (-) with a quick-release chuck installed on it for securing the electrode-tool, made in the form of a hollow or solid, single or composite electrode-tool, the system for supplying working fluid to the processing zone includes a container with a working fluid, a fine filter at the outlet of the container, a pump, a pressure regulator of the working fluid, connected through a flexible pipeline, with the pipeline connected to a hollow rod for supplying the working fluid to the cavity of the rod in the quick-release chuck to the electrode-tool and to the processing area , and the system for collecting and discharging waste liquid and electroerosion products washed out of the processing zone during the piercing process contains a bath connected by a pipeline with a coarse filter installed in it, and the mentioned container with working fluid, and a table is installed in the bath for placement on it with the clearance of the workpiece.