The 6-point use element analysis of the fixture base plate designed by UG plastic mold
. When the base plate is used on a machine tool, it is easier to set up and install the fixture by setting threaded holes, reaming holes and slots, etc. It is generally made according to the shape of the machining center table. The function includes adjusting the height of the workpiece, protecting the worktable of the machine tool, and adjusting the orientation of the workpiece according to the needs, and processing multiple sides simultaneously.
1. Types of bottom plate and base
The vertical machining center mainly uses the bottom plate. In addition to the base plate, the horizontal machining center also has a single-sided base, a double-sided base and a four-sided base.
figure 1
In order to correspond to various workpiece sizes, horizontal machining centers also use six-sided and eight-sided bases. The darker orange mark of the workpiece in Figure 2 is the surface that can be processed.
Figure 2
2. Types of bottom plate and base mounting surface
The mounting methods of the bottom plate and the mounting surface of the base fixture include T-slot form, bolt hole form, reference hole form, etc. In addition, in the actual processing and use, in order to make the accuracy of the machining center and the accuracy of the fixture mounting surface as perfect as possible, there is also a form of self-processing.
Figure 3 Advantages and disadvantages of typical T-slots, bolt holes, and reference holes
The inclination of the ground of the factory where the machine tool is located, the inclination of the spindle after many years of use, etc., each machine tool will have individuality. The remaining material held by the fixture installation surface can be processed to make it fit the individuality of the machine tool, so that the fixture installation surface Higher accuracy. There is also a form of disassembly and assembly of tooling and workpieces that can be performed outside the machine tool: quick tooling.
Three, determine the size and positioning method
When selecting the bottom plate and base, you must first confirm the size and positioning method in advance. The basic size of the horizontal machining center is 400X400, 500X500, 630X630, 800X800. According to different machine tool manufacturers, there are also sizes such as 300X300, 1000X1000, and special sizes such as 550X550 are also produced by machine tool manufacturers. The size of the vertical machining center is different for each machine tool manufacturer, and there are no special rules for the size. Each machine tool manufacturer's worktable size has its own prescribed size, please refer to the machine tool manual.
Figure 4
The positioning of the bottom plate and base of the horizontal machining center generally uses the worktable supporting block installed in the X and Y directions, and the bottom plate and the base are positioned by fitting the worktable supporting block. The position of the worktable against the block is generally set at 0° and 270° of the machine tool worktable. The position of the worktable against the block varies according to the machine tool manufacturer. The center of the worktable of the vertical machining center is generally provided with a keyway. The X direction of the bottom plate and the base is positioned through the key slot, and the Y direction of the bottom plate and the base is positioned through the T-slot.
However, not all T-slots can be accurately positioned. Depending on the machine tool manufacturer, there are generally only one or two T-slots with positioning functions.
Fourth, confirm the maximum load of the machine tool
First confirm the maximum load of the machine tool, and secondly confirm the total weight of the workpiece, fixture, base plate, and base. The total weight must not exceed the maximum load of the machine tool. There are also designers who have calculated the weight of the workpiece, the base plate, and the base, but forgot to calculate the weight of the fixture. This is absolutely not negligible.
Figure 5
If the total weight exceeds the maximum load of the machine tool, you can choose to reduce the thickness of the bottom plate, reduce the thickness of the mounting surface of the base, or make the base hollow to reduce the overall weight.
5. Confirm the height of the base and the maximum turning diameter
When selecting the bottom plate and base, the maximum height and the maximum turning diameter of the machine tool must be confirmed in advance. Especially for horizontal machining centers, the maximum turning diameter must be checked. Generally, when the base size is 400X400, the maximum turning diameter is Φ630. When the base size is 500X500, the maximum turning diameter is Φ800. The above two sizes are more common sizes, and there is no clear stipulation that a base of this size must be used. When the fixture clamps the workpiece from top to bottom, the top of the fixture (the top of the bolt in the figure below) must be within the maximum turning diameter.
Figure 6
6. Confirmation of processing range and stroke
Confirm in advance whether the machine tool processing range (the movement range of the spindle) covers all parts of the workpiece that need to be processed. Especially when using a milling cutter to machine the surface, when retracting the tool, whether the stroke of the spindle can completely exit the workpiece range must be considered in advance during the design. If the retracting tool is not considered, it is difficult to ensure the accuracy of the surface of. When the milling cutter exits the workpiece, the minimum distance between the milling cutter and the workpiece must be more than 10mm, which means that the cutter must completely leave the scope of the workpiece.
Figure 7