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With the rapid development of computer and industrial automation technology, computer-aided design (CAD) and auxiliary manufacturing (CAM) technologies have been popularized in the sheet manufacturing industry. Nowadays, whether it is a large and medium-sized sheet metal manufacturing company or a small-scale sheet metal manufacturing company. In the workshop, sheet metal blanking is more commonly used for the CNC turret punching machine, which realizes the CNC punching of the sheet metal blanking. A turret punch or turret press is a type of punch press used for metal forming by punching.

Punching, and press work in general, is a process well suited to mass production. However, the initial tooling costs, of both the machine and the job-specific press tool, are high. These limits punch work from being used for many small-volume and prototype work. A turret punch is one way of addressing this cost. The tooling of a turret punch uses a large number of standard punch tools: holes of varying sizes, straight edges, commonly-used notches, or mounting holes. By using a large number of strokes, with several different tools, in turn, a turret press may make a wide variety of parts without having to first make a specialized press tool for that task. This saves both time and money, allowing rapid prototyping or for low-volume production to start without tooling delays.

A typical CNC turret punch has a choice of up to 60 tools in a “turret” that can be rotated to bring any tool to the punching position. A simple shape (e.g., a square, circle, or hexagon) is cut directly from the sheet. A complex shape can be cut out by making many squares or rounded cuts around the perimeter. As a press tool requires a matching punch and die set, there are two corresponding turrets, above and below the bed, for punch and die. These two turrets must rotate in precise synchronization and with their alignment carefully maintained. Several punches of identical shapes may be used in the turret, each one turned to a different angle, as there is usually no feature to rotate the sheet workpiece relative to the tool.

Most turret punches are CNC-controlled, with automatic positioning of the metal sheet beneath the tool and programmed selection of particular tools. A CAM process first converts the CAD design for the finished item into the number of individual punch operations needed, depending on the tools available in the turret.

The precise load-out of tools may change according to a particular job’s needs. The CAD stage is also optimized for turret punching: an operation such as rounding a corner may be much quicker with a single chamfered cut than a fully rounded corner requiring several strokes. Changing an unimportant dimension such as the width of a ventilation slot may match an available tool, requiring a single cut, rather than cutting each side separately. CAD support may also manage the selection of tools to be loaded into the turret before starting work.

As each tool in a turret press is relatively small, the press requires little power compared to a press manufacturing similar parts with a single press stroke. This allows the tool to be lighter and sometimes cheaper, although this is offset by the increased complexity of the turret and sheet positioning. Turret punches can operate faster per stroke than a heavier tool press, although of course many strokes are required. A turret punch can achieve 600 strokes per minute.

The CNC punching die rotary head press is a computer-controlled CNC punching and nibbling press with a mold library. It can perform single-part or multi-part processing programming for sheet metal unfolded parts through computer-aided design/automatic programming software Optimization, precise positioning of the plate in the x and y directions through numerical control, and automatic selection of molds in the turret mold library of the machine tool for automatic processing.

1. The working principle of CNC turret punch press

There are two main types of CNC turret punch presses from the shape of the bed: open and closed, or C-shaped and O-shaped. The C-shaped fuselage is characterized by the main drive turret, rotating mold, and turret positioning precision components are installed on the main bed, and the sheet positioning mechanism and feeding system components are installed on the auxiliary bed, as shown in the figure below. The rotary head 1, the worktable supporting and placing the sheet to be punched, the clamp 3 that clamps and moves the sheet, and the related control system.

The O-shaped body adopts a closed frame structure, which has good rigidity and can effectively resist the side thrust during nibbling. The accuracy of the machine tool is good, the life of the mold is high, and quality of the blanking parts is good.

The working principle is shown in the figure below. The sheet to be punched is clamped on the worktable by the clamp 10. The workbench is composed of upper and lower slide blocks and a transmission system. The upper and lower slide blocks are respectively driven by the ball screw and ball nut transmission system of the electro-hydraulic pulse motor, so that the upper and lower slides move along the x, Movement in the y direction, so that the sheet is fed along the x and y directions.

The rotary head of the punch press consists of an upper turntable 1 and a lower turntable 9. The detailed structure is shown in the figure below. There are several convex molds in the upper mold base 2 in the upper turntable 1, the upper mold base 2 is fixed on the plate 4 through the journal, and the lower turntable 9 is installed with the concave mold through the lower mold base 8. When the mold is changed, the upper and lower plates of the rotary head rotate at an angle synchronously and then stop, and the neck of the upper mold base 2 is embedded in the T-shaped groove of the slider of the press. When the slider moves down, the punch also moves down to complete a punching process.

2. Processing characteristics of CNC turret punch press

The CNC turret punching machine is used for CNC punching of the sheet metal. In addition to the CNC machining technology, the punching process is different from the traditional punching method, so it has automatic and fast die change, strong versatility and high productivity. , The shape of the processed parts is not restricted by the mold structure and other advantages. In addition, the CNC turret punch also has the following characteristics.

• Using multiple molds

The upper and lower turntables of the press are equipped with multiple molds for selection during processing, breaking the concept that stamping processing cannot be separated from special molds.

• High motion accuracy and reliability

Using high-precision ball screws and rolling guides, it has high motion accuracy and reliability.

• High precision of stamping parts

The positioning accuracy is generally ±0.1mm, up to ±0.05~±0.07mm.

• High productivity

Compared with ordinary punching, the productivity can be increased by 4~10 times, especially for single-piece and small batch production, which can increase the productivity by 20~30 times.

• Low cost

Reduce mold design and manufacturing costs and shorten the production preparation cycle.

• Low labor intensity

Except for loading and unloading, all holes can be punched out automatically, and the production area can be saved at the same time.

3. Processing application of CNC turret punch press

The CNC turret punching machine is used to perform CNC punching processing on the sheet material, which can complete the processing of holes of different sizes and different shapes on the parts at one time and can also use a small punch to punch larger round holes, square holes, and waists by nibbling. Shaped holes and contours of various curved parts can also be processed with special processing techniques, such as shutters, shallow stretching, counterbores, flanging holes, ribs, embossing, etc. The following table lists the technical parameters of CNC turret punch presses.

Technical parameters of CNC turret punch press

The following table shows the product parameters of the VT-300 CNC turret punch press produced by our company.

Product parameters of VT-300 CNC turret punch press

In order to meet the current market requirements of rapid, efficient, complex and flexible production in the manufacturing industry, CNC turret punch technology is developing in the direction of digitization, integration and intelligent information.

4. Advantages and Limitations of the CNC Turret Punch

The prospect to improve part appearance and precision with inexpensive specific tools in the turret press is in some cases overlooked. Mainly where nonstandard designs and components are concerned, the manufacturer is likely to advise the selective use of particularly shaped tools. Special tools, appropriately designed and used, can considerably improve dimensional control while minimizing burrs and improving feature appearance.

Certain design functions make the CNC press a prospect for better quantity manufacturing runs. For example, firmly spaced hole patterns and louvers as generally used for ventilation purposes, may require the use of two or even three progressive stations in a tough tool die to space the openings– at substantial added cost. This added tooling cost presents the CNC press its economical quantity strength in this example.

The CNC press pairs the distinct benefit of highly flexible manufacturing of prototypes with rather inexpensive manufacturing quantities. This is due to the extraordinary variety of standard punch configurations offered which makes the cost and lead time connected with special tooling not needed.

Another perk of CNC press processing is the incredible design versatility in configuration and size of features within the part. Newer machines, particularly models with indexable tool stations, make the nibbling of very large and complicated features a practical reality.