Installation of waterjet cutting of metal with water under pressure

Principle of operation

Tap water is purified from impurities. The water is then fed into a pump where it is compressed under a pressure of 4,000 bar and fed into the nozzle of the cutting head. The cutting head is mounted on a support that moves back and forth across the workbench. When the valve is open, a stream of water is drawn out of the nozzle, the diameter of which is Ø 0.10-0.5 mm. In this case, its speed reaches 900 m/s. The abrasive mixer, where the abrasive cloth is supplied, is located slightly below the nozzle. Water mixes with the abrasive and accelerates its particles up to 250 m/s over a length of 7-10 cm. The mixture at a very high speed comes into contact with the material being processed, fixed on the working plane, and cuts it. A mixture of water, abrasive and small particles of the material being cut settles under the work table at the bottom of the bath.

The bath must be filled with water before starting work to effectively dampen the flow. If a sediment removal system is used, the bath is mechanically cleaned and the equipment can therefore operate continuously. When cleaning manually, the machine must be turned off for 1-2 days. All installation mechanisms are controlled by a CNC unit, which controls the pump, opens and closes the water and abrasive valves, and is also responsible for moving the support and cutting heads. The jet cutting process is absolutely fire - and explosion-proof.

Exploitation

Installations for waterjet cutting must be operated taking into account the following rules:

• before turning on, you need to make sure that all mechanical components, electrical cables, protection systems, and the presence of safety panels are intact;
• work only in climatic conditions declared by the manufacturer as acceptable;
• control the pressure of the mixture of water and abrasives to ensure high-quality cutting, as well as prevent damage to the hydraulic line and pump;
• use only high-quality components;
• carry out technical inspections, maintenance and repairs in a timely manner;
• when replacing the nozzle, tighten the fastenings so as not to damage it;
• use personal protective equipment to reduce the likelihood of operator injury.

Many manufacturers provide for expanding the functionality of machines. If necessary, you can install an abrasive removal device, a diaphragm-type pump for working with aggressive media, a loader or a beam crane for transporting the tank.

Areas of use

Rocketry and aircraft manufacturing - where carbon fiber processing of titanium alloys and high-temperature alloys is required. All areas of construction. Waterjet machines are used to cut reinforced concrete slabs, stones, hard floor clay and porcelain tiles; for creating mosaics, unique panels, inlays from natural granite and marble. Regular and figured cutting of stones of natural and artificial origin.

Cutting glass - reinforced, composite and plexiglass. Woodworking - structural or artistic cutting of hard wood (for example, oak), chipboard panels or laminite. Cutting various plastics - creating complex shapes and components. Tool production – production of parts requiring high precision for machine tools and production equipment. Food and light industry - cutting frozen briquettes and elastic materials can be done only with water and without abrasive materials.

Machine bath

The load-bearing parts of the machine are made of non-corrosion steel and can be easily replaced in case of their breakdown or failure. To base the material being processed, quick-release ribs are attached to the load-bearing supports, this makes it possible to maximally protect machine parts from the effects of waterjet.

To protect against dust and noise in the working area, the machine bath is equipped with a system for quickly filling and removing water, which allows cutting material completely immersed in water. The dust that is formed as a result of the operation of the machine settles in the liquid, while the noise level during cutting is no more than 70 dB.

Waterjet cutting technology

The operation of waterjet cutting involves processing the workpiece with a water jet under high pressure with the addition of a cutting agent in the form of small particles of hard rock to the water. For precise positioning of the cutting jet, a laser and a special guide head made of durable alloy are used.

Rice. 1 The working operation of cutting material under high pressure on a waterjet machine.

The cutting operation takes place under the influence of an abrasive mixture through the use of a special pump, the characteristics of which determine the thickness of the cut and the processing speed of the workpiece. To control the process, a power regulator is installed on the machine, which allows you to change the thickness and cutting speed of the workpiece. When processing the most durable materials, a three-component filler is used, while less durable materials use a two-component mixture (water + abrasive).

A major role in the technological process is played by water pressure, which must have operating parameters of at least 4700 kg/cm2 and a speed of up to 1200 m/sec.

For precise positioning of the jet, special nozzles are used, which have different outlet diameters, which allows you to adjust the thickness of the cut by changing the head. The service life of water nozzles is usually 60 - 100 hours. after the expiration of which they are replaced.

To prepare the abrasive mixture, a special mixing chamber is installed on the machine, where various components are mixed according to a given program.

To automate processing operations, an automation unit is used, which regulates the cutting operation and the feed rate of the cutting material, and also compensates for taper through the use of Flow Dynamic Waterjet technology. The system automatically adjusts the positioning of the head with a change in the direction of the nozzle angle.

Waterjet machines are used for cutting materials:

1. of stainless steel;
2. aluminum;
3. titanium;
4. granite;
5. marble;
6. carbon fiber;
7. glass

with the formation of an even cut of the required thickness.

Machine drive system

The machine is equipped with a cantilever design with a belt-type drive for moving the axes. The belt drive is easy to operate, easily replaced if broken, and is ideally suited for processing on waterjet cutting machines, as it is resistant to the impact of abrasive material on the moving parts of the drive.

To increase the accuracy of movement of the cutting head, linear inductive sensors are installed on the machine, which will allow achieving positioning accuracy of ±0.001 mm. Movement occurs along linear guides, which ensures high positioning accuracy, smooth operation and reduced movement time.

High pressure pump

One of the main components of waterjet cutting is the high-pressure pump.

CNC system

The machine control is a numerical control system.

Remote control with handwheel

To operate the machine, it is convenient to use a flywheel and a remote control. This device allows you to perform corrections or adjustments as efficiently and quickly as possible.

Tank with abrasive

The design of the tank allows you to replenish the abrasive even while the waterjet equipment is operating, which can significantly save time.

The tank is equipped with sensors for the level of material used.

Device for controlling the constant gap of the cutting jet

This device, using a special sensor, controls the optimal distance between the material being processed and the nozzle, as a result of which the highest quality cut is obtained and does not allow the nozzle feeding the mixture to collide with the material that we are processing.

Swivel head

The head rotation angle allows rotation in 2 planes with a maximum tilt angle of up to 65 degrees, which practically allows for chamfering, curved plane, and for cone compensation during processing. When processing complex planes, the machine works with 5 coordinates.

Material scanning system

In the process of processing parts on waterjet cutting machines, a problem arises associated with the uneven surface of the material being processed.

To eliminate this problem, it is possible to install a laser or ultrasonic material scanning system on the equipment. This system scans the material before processing at a certain interval, which makes it possible to maintain a given gap during material processing and helps ensure high processing accuracy. When producing small parts, it is possible to scan only the cut-in points.

Abrasive amount control sensor

The abrasive supply control sensor allows you to check the supplied abrasive material and quantity during processing, which involves making a cut without the constant presence of a worker at the machine, and even stopping the processing process as a result of foreign objects or materials entering the cutting head, such as the remains of a bag or other material factions. The range of possible values ​​is set by the operator from the CNC rack and can be changed during processing.

Abrasive removal device

At the GAO it is possible to install a system for removing waste material and abrasive particles, which consists of a pump and a settling tank. A characteristic feature of this system is the use of a diaphragm pump, which is extremely easy to maintain and is suitable for working in aggressive environments. For ease of operation, the container for used abrasive is equipped with quick-release connectors for connecting hoses and is adapted for movement by a crane, hoist or loader.

Material loading device

Waterjet equipment is equipped with various devices for loading the processed material. Most often, beam cranes are used with hoists, with mechanical or vacuum grips; hydraulic and pneumatic lifting mechanisms with adjustable arms that support material at critical points.

Machine design

working head device

Waterjet cutting is the processing of solid materials with a density of about 2.5 tons per cubic meter using a mixture of solid particles and water according to the principle of erosion. The cutting mixture is supplied to the material under powerful pressure, a small-diameter water stream through a specially shaped head. The processing speed depends on the material parameters.

CNC waterjet machines are a combination of several modules, including mounted ones:

• solids feed mechanism;
• table in the form of a bathtub;
• high pressure water pump;
• portal;
• movable head;
• pressure distribution mechanism;
• container for abrasive mixture.

Additionally, the waterjet cutting machine is equipped with automatic measurement and control systems that increase accuracy.

The heads are made from artificial minerals, they are quite expensive and require periodic replacement. Mixing tubes made of durable metals must also be replaced.

Processing is carried out on a specially designed table.

The waterjet cutting method has many advantages:

• when operating a specialized machine, waste is minimal;
• the surface of the stone is not given unnecessary roughness;
• the metal is not covered with scale;
• processing occurs at room temperature, overheating of the material is avoided;
• the quality of the resulting parts is the highest;
• a wide variety of types of waterjet cutting are possible, including those simulating hand carving;
• the material is not deformed;
• you can completely remove the front layer from the workpiece or chamfer it;
• No harmful vapors, gases, or soot are emitted;
• You can process slabs more than 15 cm thick.

CNC waterjet cutting equipment operates automatically; manual labor is not used. All processed materials fully retain their original qualities.

Functions of waterjet machines

The main purpose of using the equipment is high-quality cutting of materials, drawing up complex contours or artistic patterns.

New generation waterjet machines can: cut at a speed of up to 15 m/min., rotate the cutting tool at an angle of up to 90 degrees, maintain the height of the cutting head, supply water and control the speed of its movement, work 4 times faster due to the simultaneous installation of four independent heads, compensate for lags in flow and cone when cutting, and obtain a high result, create a chamfer when processing material, distribute the abrasive absolutely accurately, perform work with a remote control, in case of an emergency power outage, finish the operation, execute a loaded program and quickly switch when changing modes, control the cutting price.

Selection principles

When choosing waterjet machines, you need to consider the following criteria:

• area of ​​the working table, accuracy of positioning of the working tool above its surface;
• type of installed water pump and its cooling system;
• accuracy of dosing of abrasive material;
• availability of a water purification system;
• type of installed working tool;
• water tank volume;
• control method - manual or automated;
• possibility of expanding functionality;
• cost of equipment, availability of warranty from the manufacturer.

Advantages and disadvantages

Waterjet machining machines have a number of advantages:

• cutting workpieces of various thicknesses without deformation or thermal effects;
• minimal loss of material due to the small thickness of the jet;
• continuous operation of equipment;
• high quality seam: smooth, even surface with minimal roughness;
• formation of complex cutting contours;
• batch processing of thin sheet materials;
• high cutting precision;
• during processing, the part is not subjected to mechanical stress, therefore it retains its strength properties and structure;
• there is no need to use traditional working tools when cutting, which require careful work, frequent maintenance, and restoration;
• ease of operation, repair, maintenance;
• cutting of any metals or alloys is possible;
• There are no emissions of harmful chemical compounds during operation.

Waterjet machines also have disadvantages:

• high cost of the abrasive compounds used;
• low cutting speed of thin sheet metal;
• short operating life of the cutting head, as well as components;
• When in contact with water, iron and alloys based on it are susceptible to corrosion processes.

Waterjet cutting precision

Manufacturers and cost

The waterjet cutting machine is manufactured by such well-known companies: ALICO, Bystronic, Caretta Technology, OMAX, Resato. For almost all models, consumables and components manufactured by AccuStream, BHDT, Thueringer, and UHDE are available.

Average prices for equipment are as follows:

• desktop CNC machines - from 90 thousand rubles;
• portal industrial installations with CNC - from 2.5 million rubles;
• special equipment with three working tools - from 250 thousand euros.

Advantages of waterjet machines

Effective work with all materials: impermeable, brittle, viscous, composite, inaccessibility of high temperatures in the cutting zone (maximum - 90ºС), as a result, the design of the material is preserved, less production waste due to the cutting accuracy with a narrow part of the cut (only 1 mm), the edge of the finished product is smooth, does not require further processing, the thickness of the cut sheet reaches from 150 to 300 mm, dust and toxic compounds harmful to human well-being do not appear, to increase productivity, it is possible to cut several sheets at once in a stack, low cutting voltage allows do without clamping the sheet being processed, the highest cutting speed, quick reconfiguration of equipment for a new part.

The operating principle of the machines.

The operation process of the machines is carried out as follows: the machine pump supplies water to the nozzle, the pressure ranges from two thousand to seven thousand PA

As a result, a high-speed jet is formed due to the jet, particles of material are washed away along the cutting line, if you supplement the water jet with abrasive, its power will increase several times, as a result of which the machine can cut a workpiece with a thickness of 305 mm. The cutting edge of the jet can move in any position depending on the processing of the workpiece.