In the application of CNC machine tools for the production of manufactured goods and parts process, factors that affect the quality of many parts, such as precision CNC machine tools, workpiece material, workpiece heat treatment, processing, coolant, tool and many other factors. Among them, the exact parameters of the tool set, has been very little care and attention by everyone here will focus on the CNC machine tools for accurate tool setting methodological characteristics and trends.
The basic coordinate relations in general, there are two commonly used coordinate systems: one is the machine coordinate system, the other is the workpiece coordinate system. Machine coordinate system is inherent in the machine coordinate system, the origin of the machine coordinate system or machine called machine zero point zero.
In order to facilitate the calculation and programming, we need to establish the workpiece coordinate system in the machine coordinate system. The coordinate origin as a point on the workpiece (also referred to as the program origin) coordinate system is established, this coordinate system is the workpiece coordinate system. Daily work, we have to try to make the program coincides with the reference design, assembly reference.
CNC machine tools and methods commonly used within the machine tool knife
Normally, a machine tool coordinate system is fixed and the workpiece coordinate system can be established separately according to the actual needs of a number of processing technology, such as the G54, G55, etc. to select a different workpiece coordinate system.
When purpose knife CNC machining, CNC programs are taking the path of the trajectory of the spindle tool tip. Tool cutting trajectory throughout the site needs to be precisely controlled in the machine coordinate system. This is because the machine coordinate system is a reference tool only. Programmers can not know the exact dimensions of the various specifications of the tool during programming, in order to simplify the programming, which requires the use of a uniform reference during programming, then when using the tool for machining the exact length and radius of the tool with respect to the reference size corresponding offset to obtain the exact position of the tool tip. Therefore, for the purposes of the knife it is to determine the tool length and radius, so that the processing of determining the exact location of the tip in the workpiece coordinate system.
Common methods of outer blade cutting machine
Is a tool presetter and measuring tip can be pre-adjusted length, diameter of the measuring instrument, which if the DNC and CNC machine tools consisting of a network, you can also be the tool length and diameter of the remote data processing center NC input in the tool parameters . Advantages of this method is to advance the tool outside the machine proofing is good, that is mounted on the machine can be used, saving auxiliary time. But the main drawback is that the measurement result is a static value, the actual process is not real-time tool wear or breakage status updates in real time and can not stretch by the machine tool caused by thermal deformation is measured.
Test method for cutting knife
Test method for cutting knives before the official workpiece, first operator in manual mode operating the machine, the workpiece is a small amount of cutting, the operator with sharp eyes, ears basis for judging to determine the current position of the tool tip, then a formal process. The advantage of this method is that no additional investment to purchase tools, equipment, and affordable. The main drawback is the low efficiency of operator skill level requirements, and prone to human error. In actual production, cut test method there are many derivative methods, such as the amount of the block method, a coloring method.
Within such way is to use machine tool provided in the machine work surface measuring device (instrument on the knife), the knife in the magazine according to pre-set procedures for measurement and the reference position or reference tool to compare the tool to get length or diameter and is automatically updated to the corresponding NC tool parameter table. At the same time, by detecting the tool can also achieve the tool wear, breakage or install model is correct or not identified.
The machine on the knife
Machine tool setter composition
Machine knife instrument generally consists of sensors, signal interface and the knife macro software.
The sensor according to work, the machine can be divided on the knife-contact tool and laser instrument on the knife categories. Wherein the contact tool setting instrument itself repeated accuracy of 1μm, but also depending on the signal transmission for the knife, and further subdivided into the following categories: Cable-type instrument on the knife; type infrared instrument on the knife; type of radio the knife.
Cable-type instrument on the knife, eliminating the need to convert the signal components and the knife has the best single piece of money, and therefore the most common in the work, but its drawback is that there are cable boxes, limiting the knife instrument applications most suitable for small and medium size three-axis milling machine / machining center.
Type infrared instrument on the knife, the signal transmission range is generally less than 6m. The advantage is the use of coded HDR (high-speed data transmission) infrared technology to avoid the cable boxes inconvenience and potential security threats, after the knife can be removed at any time from the work surface does not occupy working space and can be more than one machine Shared one for the knife to reduce overall costs. The disadvantage is that when used on small machining centers cost is not high. Its characteristics of the decision, the class on the knife used for medium and large machine tool CNC vertical lathe and so on.
Radio Formula on the knife, the radio signal transmission range is generally 10 meters. The advantage is a wide range of radio signal transmission and less susceptible to environmental impacts, at any time after the knife can be removed from the work surface does not occupy working space and multiple machines can share one instrument on the knife which can reduce overall costs. Class on the knife used for large / heavy machine tools.
Machinery manufacturing tool is a tool for cutting, also known as cutting tools. The vast majority of machine tool is used, but also the hand. Since the tool machinery used basically used for cutting metal material, the term "tool" is generally understood to be on the metal cutting tools.
Tool selection is an important part of CNC machining process not only affects the machining efficiency, but also directly affect the machining quality. CNC tool is one of the prerequisites to improve processing efficiency, its choice depends on the geometry of the machined parts, material condition, fixtures and machine selection tool rigidity.
Different tools in NC machining process uses are different, then the CNC machining processes commonly used tool, what does?
Metal cutting tools are most widely used as a tool. It can be machined on a lathe cylindrical, flat end, thread, bore, it can also be used for grooving and cutting and so on. Turning the whole structure can be divided into tools, welding tools and fabricated mechanical clamping blades turning. Mechanical clamping tools can be divided into blades of the machine tools and indexable turning tools. Mechanical clamping tools, the cutting is stable, workers do not have to throw away, so in modern production more and more applications.
2. Hole Cutter
Processing tools can generally be divided into two categories: one is machined from solid material out of the hole cutter, commonly used twist drill, center drill and drill hole; the other is a hole on a workpiece has been re machining tool, commonly used reamers, reamer and boring knives. For example, in the illustrated standard high speed steel twist structure. The front end of the working portion (blade) of the cutting part, bear the main cutting work, the rear end of the guide portion, serving as a guide drill is part of the cutting portion of the reserve.
Milling is a widely used multi-blade rotary cutter, a lot of its kind. By Use: 1) machining plane used, such as cylindrical milling cutter, end mills, etc; 2) Processing with grooves, such as end mills, T-shaped knife and angle milling cutters; 3) forming surface machining use, such as semi-circular convex and concave milling cutters and other complex forming surface machining with a cutter. Milling is generally higher productivity, larger surface roughness values.
Broach is a precision machining and cutting efficiency higher than the multi-tooth tool, widely used in mass production, within the process a variety of outer surface. Broach the different workpiece surface, it can be divided into various internal and external broach broach categories. When using broach processing, in addition to the workpiece material selection tooth rake angle, relief angle, depending on the size of the workpiece surface (such as hole diameter) to determine the size of the broach, but also need to determine two parameters: (1) the teeth lead angle af [ie around twice the tooth (or teeth group) radius or difference in height]; (2) the pitch p [that is adjacent to the axial distance between the teeth twice].
5. Gear Cutter
Gear Cutter is the tool used for machining of gear tooth. According to the principle of the tool, gear shaping into gear cutters and develop into a gear cutter. Common gear shaping tool has a disk-shaped gear cutter and finger gear cutting tools. Commonly used tool has developed into gear shaper cutters, gear hobs and shaving knives. Selection of gear hob and shaper cutters, should note the following: (1) basic tool parameters (module, pressure angle, addendum coefficient, etc.) should be processed with the same gear. (2) the accuracy of the tool should be commensurate with the level required gear machining precision. (3) Tool rotation should be possible with the same rotation processing gear. When the roll Qiezhi gear, generally with left-handed cutter.