Machining centers are often divided into vertical machining centers, horizontal machining centers, gantry machining centers and universal machining centers according to the state of the spindle in space. The spindle of the machining center is called a vertical machining center in a vertical state in space, and the horizontal machining center is called a horizontal machining center in which the spindle is in a horizontal state in space.
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(1) Vertical machining center: the structural form is mostly fixed column type, and the workbench is rectangular, which is suitable for processing disc, sleeve and plate parts. Vertical machining centers usually have three linear motion coordinates, XYZ axis, and a fourth axis A axis can be installed on the table.
The vertical machining center is easy to clamp, easy to operate, easy to observe the processing situation, and convenient to debug the program, but due to the influence of the height of the column and the tool change mechanism, it cannot process parts that are too high. The vertical machining center has a simple structure, a small footprint and a low price.
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(2) Horizontal machining center: Usually a movable column is used, and the headstock is between the two columns and moves up and down along the guide rail. Horizontal machining centers usually have three linear motion coordinates, facing the machine tool, moving left and right is the X axis, moving back and forth is the Z axis, and moving up and down is the Y axis. Horizontal machining centers can also have a fourth axis, the A-axis, mounted on the table. Parts such as helical cylindrical cams can be processed. The horizontal machining center is inconvenient to observe when debugging the program and try to cut pins, it is inconvenient to monitor during processing, and it is inconvenient to clamp and measure parts, but it is easy to arrange pins during processing. Compared with the horizontal machining center, the structure of the vertical machining center is complex, the floor area is large, and the price is higher.
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(3) Longmen machining center: Most of its spindles are vertically set, with ATC system and replaceable spindle head attachments. The system software has many functions and can be used for multiple purposes, suitable for processing large parts.
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(4) Universal machining center: The universal machining center is a five-sided machining center, which has the functions of a vertical machining center and a horizontal machining center. After the workpiece is clamped once, it can complete the machining of all sides and top surfaces except the mounting surface. Common universal machining centers are:
1. The spindle can be rotated 90°, which can work like a vertical machining center or a horizontal machining center.
2. The spindle does not change direction, and the worktable rotates 90° with the workpiece. Complete the processing of the five faces.
In short, according to the number and function of the workbench: there are single-workbench machining centers, double-workbench machining centers, and multi-workbench machining centers.
The structure of the machining center
(1) Basic components. It is the basic structure of the machining center, which is composed of bed, column and workbench. They mainly bear the static load of the machining center and the cutting load generated during machining, so they must have sufficient rigidity. These large parts can be cast iron parts or welded steel structural parts, which are the largest volume and weight parts in the machining center. AKIRA-SEIKI castings are made of high-grade Meehanite castings, which are heat-treated for high stability.
(2) Spindle components. It is composed of spindle box, spindle motor, spindle and spindle bearing and other parts. The start, stop and speed change of the spindle are all controlled by the CNC system. For more CNC knowledge, search the public account "CNC programming teaching" to get free tutorials, and participate in the cutting movement through the tool installed on the spindle, which is the power output of cutting processing. part. It is a key component of the machining center, which determines the machining accuracy and stability of the machining center.
(3) CNC system. The CNC part of the machining center is composed of cNc device, programmable controller PLC, servo drive device and operation panel.
(4) Automatic tool change system. It consists of tool magazine, manipulator drive mechanism and other components. When it is necessary to change the tool, the CNC system issues an instruction, and the manipulator (or by other means) takes the tool out of the tool magazine and puts it into the spindle hole. It solves the task of automatic storage, selection, handling and exchange of tools between processes in the continuous processing of multiple processes after the workpiece is clamped once.
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The tool magazine (knife head) is a device that stores all the tools used in the machining process. The tool magazine has a disk chain type and other capacities ranging from a few to hundreds. The structure of the tool arm also has various forms according to the relative position and structure of the tool magazine and the spindle, such as: single-arm type, double-arm type, etc. Some machining centers directly use the movement of the spindle box or the tool magazine to change the tool without using the tool arm.
(5) Auxiliary devices. Including lubrication, cooling, chip removal, protection, hydraulic pressure, pneumatic and detection systems and other parts. Although these devices do not directly participate in the cutting movement, they play a role in guaranteeing the machining efficiency, machining accuracy and reliability of the machining center, so they are also an indispensable part of the machining center.
(6) APC automatic pallet exchange system. In order to realize the unmanned operation of one part or further shorten the non-processing time, some machining centers search the official account "NC programming teaching" for more CNC knowledge to receive free tutorials, and use multiple automatic exchange workbenches to reserve workpieces. While it is installed on the workbench for processing, one or more workbenches can also load and unload other parts. When the processing of the parts on one workbench is completed, the workbench will be automatically exchanged to process new parts. Reduce auxiliary time and improve processing efficiency.
The main processing object of the machining center
(1) Box-type parts: Box-type parts generally refer to parts with more than one hole system, a cavity inside, and a certain proportion in the length, width, and height directions.
(2) Complex curved surfaces: It is difficult or even impossible to complete complex curved surfaces with ordinary machining methods.
(3) Special-shaped parts: Special-shaped parts are parts with irregular shapes, and most of them require mixed processing of points, lines and surfaces, such as shift forks.
(4) Disc, sleeve, and plate parts: with keyways, or radial holes, or distributed holes on the end surface, disk sleeves or shaft parts with curved surfaces, such as sleeves with flanges, with keyways or square heads Shaft parts, etc., as well as plate parts with more holes, such as various motor covers, etc. Disc parts with distributed holes and curved surfaces on the end face should choose a vertical machining center, and a horizontal machining center with radial holes can be selected.
(5) Parts that are put into production periodically: When processing parts with a machining center, the time required mainly includes basic time and preparation time, of which the preparation time accounts for a large proportion, such as: process preparation, programming parts, first piece trial cutting, etc., these The time is very long, and the use of machining centers can store the contents of these times for repeated use in the future. This saves time when machining the part later. The production cycle can be greatly shortened.
