When the base plate is used on a machine tool, the fixture can be more easily set up and installed by setting threaded holes, reaming holes, slots, etc. It is generally made according to the shape of the machining center workbench. Its functions include adjusting the height of the workpiece and protecting the machine tool workbench. , and can also adjust the orientation of the workpiece as needed to perform multi-faceted processing at the same time.
one
Types of bottom plates and bases
Vertical machining centers mainly use base plates. In addition to the basic base plate, horizontal machining centers also have single-sided bases, double-sided bases and four-sided bases.
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figure 1
In order to cope with various workpiece sizes, horizontal machining centers also use six-sided and eight-sided bases. In Figure 2, the areas marked with darker orange on the workpiece are the surfaces that can be processed.
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figure 2
two
Types of bottom plates and base mounting surfaces
The installation methods of the bottom plate and base clamp mounting surface include T-shaped groove form, bolt hole form, reference hole form, etc. In addition, in actual processing, 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.
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Figure 3 Advantages and disadvantages of typical T-shaped slots, bolt holes, and reference holes
Each machine tool has its own characteristics, such as the inclination of the floor in the factory where the machine tool is located, the inclination of the spindle after many years of use, etc. The remaining material held by the fixture mounting surface can be processed to fit the individuality of the machine tool, so that the fixture mounting surface can be customized. Higher accuracy. There is also a form of disassembly and assembly of tooling and workpieces outside the machine tool: tooling quick change.
three
Determine size and positioning method
When choosing a base plate or base, you first need to confirm the size and positioning method in advance. The basic sizes of horizontal machining centers are 400X400, 500X500, 630X630, and 800X800. Depending on the machine tool manufacturer, there are also sizes such as 300X300, 1000X1000, and special sizes such as 550X550 are also produced by machine tool manufacturers. The dimensions of vertical machining centers vary from machine tool manufacturer to manufacturer, and there are no special rules dictating dimensions. Each machine tool manufacturer has its own prescribed dimensions for the workbench of the machine tool. Please refer to the machine tool manual.
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Figure 4
The positioning of the bottom plate and base of a horizontal machining center generally uses workbench blocks installed in the X and Y directions. The base plate and base are positioned by fitting the workbench block. The position of the workbench backing block is generally set at the 0° and 270° orientations of the machine tool workbench. The position of the workbench backing block also varies depending on the machine tool manufacturer. The center of the worktable of a vertical machining center is generally equipped with a keyway. Position the X direction of the base plate and base through the keyway, and then position the Y direction of the base plate and base through the T-shaped slot.
However, not all T-shaped slots can be accurately positioned. Depending on the machine tool manufacturer, there are generally only 1 or 2 T-shaped slots with positioning function in the machine tool.
Four
Confirm the maximum load capacity of the machine tool
First, confirm the maximum load capacity 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 capacity of the machine tool. There are also designers who calculate the weight of the workpiece, base plate, and base, but forget to calculate the weight of the fixture, which cannot be ignored.
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Figure 5
If the total weight exceeds the maximum load of the machine tool, you can choose to reduce the thickness of the base plate, reduce the thickness of the base mounting surface, or make the base hollow to reduce the overall weight.
five
Confirm the base height and maximum rotation diameter
The maximum height and maximum rotation diameter of the machine must be confirmed in advance when selecting the base plate and base. Especially for horizontal machining centers, the maximum rotation diameter is something that must be confirmed. Generally, when the base size is 400X400, the maximum rotation diameter is φ630. When the base size is 500X500, the maximum rotation diameter is φ800. The above two sizes are the more common sizes, and there is no clear requirement to use a base of this size. When the clamp clamps the workpiece from top to bottom, the top of the clamp (the top of the bolt in the picture below) must be within the maximum rotation diameter.
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Figure 6
six
Confirmation of processing scope and schedule
Confirm in advance whether the machining range of the machine tool (the movement range of the spindle) covers all the parts of the workpiece that need to be processed. Especially when using a milling cutter to process the surface, when retracting the tool, whether the stroke of the spindle can completely remove the tool from the workpiece must be considered in advance during design. If retraction is not considered, it will be more difficult to ensure surface accuracy. of. When the milling cutter exits the workpiece, it must be at least 10mm away from the workpiece, that is, the cutter needs to completely leave the workpiece.
