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Let ALLES CNC tell you how to machine tool center mounting method that can improve workpiece quality

Jun 05, 2019

Compared with ordinary machine tools, CNC machining centers have the characteristics of high processing efficiency, stable quality control, and greatly reduced labor and time costs. The CNC machining centers produced by ALLES CNC have 5 Axis Machine Center, Gantry Type 5 Axis Machine Center, and VMC 3 Axis Machine Center (click to view), but in the actual machining process, there is still machining accuracy and workpiece. Problems such as unqualified quality. How to make the machining center work out the workpiece to improve? This is definitely related to the manufacturing precision of the machine tool, the machining process, the mounting method of the workpiece, and the quality of the programming. In addition to the above factors, the machining quality of the workpiece is also related to the installation of the tool. Let's talk about the specifics of ALLES CNC below.

(Click to view the CNC machining center of ALLES CNC)

Common problems and causes of tool installation:


The problems associated with the installation of the tool are: improper tool installation position, tool installation is not secure, and the tool tip and workpiece axis are not equal. There are several main reasons for the problems and their causes.


Improper installation of the tool will cause problems. The summary of the sea is often expressed as:


(1) Vibration during cutting or vibration on the surface of the tool. The cause of the tool is that the tool bar is too long or the gasket is not used properly. The secondary angle of the tool is too small.


(2) Thread profile error because the centerline of the tool tip is not perpendicular to the workpiece axis.


(3) A horn hole appears in the inner hole of the car, causing the shank to be too long.


(4) When the groove is cut or cut, the end surface is not perpendicular to the working axis or the surface of the end surface is rough. The general reason is that the tool bar is not perpendicular to the workpiece axis, and the secondary flank face of the tool is scraped with the machined surface of the workpiece.


Problems caused by weak tools:


(1) Roundness and cylindricity are overweight when turning. The cause is that the tool's fastening screws are not tightened, causing the toolholder to shift.


(2) The verticality of the end face of the car is out of tolerance, and the cause is that the tightening screw of the cutter is not tightened, so that the cutter bar is offset.


(3) The blade is broken. The cause of the blade is that the fastening screw is not tightened or the blade is in poor contact with the pad, which makes the blade loose.


Problems with the tip of the tool and the workpiece axis are not equal:


(1) The surface of the workpiece is rough during finishing, and the cause of the sharpening of the sharpening tool is too high, causing the knives of the turning tool to rub against the workpiece and scratching the machined surface.


(2) A hyperbolic profile occurs when the cone is turned, and the height of the tip is not as high as the axis of the workpiece.


(3) Use a knife to tighten the step contour. Some sizes are out of tolerance. The height of the tool tip is not as high as the workpiece axis.


(4) When the groove is cut and the thread is threaded, the knife is stuck. When the turning end face or the cutting is finished, the workpiece is left with a boss. The reason why the tool is not moved is that the cutting edge is lower than the vertical line of the workpiece.


So how to solve it? For the problems caused by the above tool installation, the tool should be installed according to the actual processing conditions, analyze the cause, and choose the correct installation method.


Solution when the turning tool is installed improperly and not securely


(1) Under normal circumstances, the tool nose should be equal to the axis of the turning tool. When roughing and turning large diameter workpieces, the tool tip is slightly higher than the workpiece axis: the tool tip is slightly lower than the workpiece axis during finishing. However, when finishing the cone and arc profile, the tool nose should be strictly equal to the axis of the turning tool.


(2) When turning the slender shaft, in order to support the tool holder or the center frame, in order to tighten the tool tip, the tool is appropriately offset to the right to form a lead angle slightly smaller than 90°. In order to generate a certain radial force, the slender shaft is pressed against the struts of the tool holder to avoid the shaft jumping; when the tool holder is not used with the tool holder or the center frame, the tool is properly installed to the left to form The lead angle is slightly larger than 90° so that the radial cutting force is as small as possible.


(3) The length of the cutting tool should not be too long to prevent cutting vibration caused by the difference in rigidity, which leads to a series of problems such as rough surface of the workpiece, vibration, knives, and knife. Generally, the length of the cutting tool does not exceed 1.5 times the height of the tool bar. When other tools or tool holders do not collide or interfere with the tailstock or the workpiece, the clamping of the tool should be as short as possible, if at the cutting position. When the length of the tool is as short as possible, the position or sequence of the installation can be changed when other tools or tool holders interfere with the center frame of the tailstock.


(4) The bottom of the knife bar should be flat. When using a gasket, the gasket should be flat. The front end of the gasket should be aligned and the number of gaskets should generally not exceed z.


(5) The turning tool should be installed firmly. Generally, two screws are alternately fastened and fixed, and the height of the tool tip and the workpiece axis are detected again after tightening.


(6) When using the machine clamp to index the tool, the blade and the gasket should be wiped clean. When using the screw to fix the blade, the tightening force should be appropriate.


(7) When turning a thread, the center line of the thread tip angle should be strictly perpendicular to the workpiece axis. The tool can be completed using a threaded tool plate and a universal angle ruler.


Ensure that the tool tip is as high as the workpiece axis


(1) When do you need to consider whether the tool tip is as high as the workpiece axis?


When using a welding tool. It is necessary to consider whether the tool tip is as high as the workpiece axis. If conditions permit, it is best to select the machine clamp indexable turning tool. Not only the durability of the blade is significantly improved, but the machining quality is stable. After the tool wears, the tool is reduced. Time, and because of the high manufacturing precision of the arbor, the blade mounting position is accurate, and the position of the cutting edge and the bottom of the shank is fixed, so that the tool tip is mounted at the same height as the workpiece axis, which reduces or even avoids adjusting the height of the cutting edge. However, after long-term use on the machine tool, the height of the tool holder is lowered due to the wear and tear of the guide rail, so that the tool tip is lower than the workpiece axis. When the tool holder can be indexed, it is also necessary to consider whether the tool tip is equal to the workpiece axis.


(2) Method for detecting the height of the tool nose and the workpiece axis


The easiest way is to use visual inspection, but it is often inaccurate due to factors such as visual angle and light. It is usually only used for roughing large diameter workpieces. In other processing situations, the appropriate test method is required.

(3) Instructions for using the self-made knife and the knife


It should be noted that the height tool setter shown in Figure 1 is used. The tip of a knife should be precisely adjusted to the same height as the spindle axis by trial cutting, etc., and then the tool setting instrument should be placed on the inner horizontal longitudinal rail surface and the middle slide rail surface of the machine tool respectively to make the knife blade After the lower surface is equal to the tip, adjust the thickness of the washer separately. After locking the nut, it can be used as a tool for future installation. The tool setting tool can be placed on different height planes according to different types of tools: the height of the blade can be adjusted by adjusting the washers for different machine tools, and the tool tip can be used flexibly to the tool A or B face. Height and wide range of use.


When the machining center is working, the selection and installation of the tool is correct, and the impact on the machining quality and the tool life is very significant. The operator should pay attention to the installation problem of the tool, and according to the actual situation of the site, use a reasonable method to quickly and correctly install the tool to ensure the smooth progress of the cutting and stable control of the workpiece processing quality.

More details: www.allescncmachine.com

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