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 the space. The main shaft of the machining center is vertical in space, called vertical machining center, and the main shaft is horizontal in space, called horizontal machining center.

1. Classification of machining centers

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 the space. The main shaft of the machining center is vertical in space, called vertical machining center, and the main shaft is horizontal in space, called horizontal machining center.

Vertical Machining Center: The structure is mostly fixed column type, and the worktable is rectangular, suitable for processing plate and board parts. Vertical machining centers usually have three linear motion coordinates, XYZ axis, and a fourth axis A axis can also be installed on the worktable.

The vertical machining center is convenient for clamping, easy to operate, easy to observe the processing conditions, and easy to debug the program. However, due to the influence of the height of the column and the tool change mechanism, parts that are too high cannot be processed. The vertical machining center has a simple structure, a small area and a low price.

Horizontal machining center: usually adopts a movable column, the headstock is between the two columns and moves up and down along the guide rail. The horizontal machining center usually has three linear motion coordinates. Facing the machine tool, the left and right movement is the X axis, the front and back movement is the Z axis, and the up and down movement is the Y axis. The horizontal machining center can also install a fourth axis A axis on the worktable. It can process parts such as spiral line, cylindrical cam and so on. It is inconvenient to observe the debugging program and test pin cutting of horizontal machining center, monitor during processing, and it is inconvenient to clamp and measure parts, but it is easy to discharge pins during processing. Compared with the vertical machining center, the horizontal machining center has a complicated structure, a large area, and a higher price.

Gantry machining center: Most of its spindles are vertically set up, with ATC system, and with replaceable spindle head attachments. The system software has many functions and can be used for multiple purposes in one machine, suitable for processing large parts.

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 all the side and top surfaces except the mounting surface. Common universal machining centers are as follows: 1 The main shaft can rotate 90°, and it can work like a vertical machining center or a horizontal machining center. 2 The spindle does not change its direction, and the worktable rotates 90° with the workpiece. Finish the processing of five sides.

According to the number and function of the workbenches: there are single workbench machining centers, double workbench machining centers, and multi-workbench machining centers.

2. The structure of the machining center

From an overall point of view, it is mainly composed of the following parts.

(1), basic components. It is the basic structure of the machining center, which is composed of a bed, a column, and a table. 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. They are the largest volume and weight parts in the machining center. AKIRA-SEIKI castings are made of high-grade Meehanite castings, which have high stability after heat treatment.

(2), the spindle component. It is composed of main shaft box, main shaft motor, main shaft and main shaft bearing. The spindle's start, stop and speed change are all controlled by the numerical control system, and participate in the cutting movement through the tool mounted on the spindle, which is the power output part of the cutting process. It is a key component of the machining center, which determines the machining accuracy and stability of the machining center.

(3), CNC system. The numerical control 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 is composed of tool magazine, manipulator drive mechanism and other components. When the tool needs to be changed, the CNC system issues an instruction, and the manipulator (or through other means) takes the tool out of the tool magazine and loads it into the spindle hole. It solves the task of automatic storage, selection, transportation and exchange of tools between processes in the continuous processing of multiple processes after the workpiece is clamped once.

Tool magazine (cutter head) is a device that stores all the tools used in the machining process. The tool magazine has disc type, chain type, etc. The capacity ranges from a few to several hundred.

The structure of the tool arm also has many forms according to the relative position and structure of the tool magazine and the spindle, such as: single-arm type, double-arm type, and so on. Some machining centers do not use the tool arm but directly use the movement of the headstock or tool magazine to change the tool.

(5), auxiliary device. Including lubrication, cooling, chip removal, protection, hydraulics, pneumatics, and detection systems. Although these devices do not directly participate in the cutting motion, 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) In order to realize the unmanned operation of the APC automatic pallet exchange system or to further shorten the non-processing time, the machining center adopts multiple automatic exchange worktables to store the workpieces, and one workpiece is installed on the worktable for processing. In addition, one or several workbenches can also load and unload other parts. When the parts on a workbench are processed, the workbenches are automatically exchanged to process new parts, which can reduce auxiliary time and improve processing efficiency.

3. The main processing objects of the machining center

1). Box parts: Box parts generally refer to parts that have more than one hole system, a cavity inside, and a certain proportion of length, width, and height.

2). Complex curved surface: It is difficult or even impossible to complete complex curved surface using ordinary machining methods.

3). Special-shaped parts: Special-shaped parts are parts with irregular shapes, and most of them require point, line, and surface multi-station mixed processing. Such as fork and so on.

4). Disc, sleeve, plate parts: with keyway, or radial hole, or distributed hole system on the end surface, curved disc sleeve or shaft parts, such as flanged shaft sleeve, with keyway or square head The shaft parts, as well as the plate parts with more porous processing, such as various motor covers. Disc parts with distributed holes and curved surfaces on the end surface should choose a vertical machining center, and a horizontal machining center with radial holes should be selected.

5). For parts that are put into production periodically, when machining parts with a machining center, the required time mainly includes basic time and preparation time, of which the preparation time accounts for a large proportion, such as the first trial cutting of process preparation and programming parts, etc. The time is very long, and the processing center can be used to store the content of these times for repeated use in the future. In this way, you can save this time when processing the part later. The production cycle can be greatly shortened.