Principle and design of manual economical CNC tool holder

The principle and design of manual economical CNC tool holder. Chongqing University of Chongqing 433 Chongqing University Chongqing coffee called Zhang Jisheng Zhang Genbao has the function of two coordinate linkage.

With the development of science and technology and the advancement of manufacturing technology, and the increasing demand for diversification of products, the upgrading of products has accelerated. The diversification of product varieties has promoted the development of CNC machine tools in a situation where the scale of production has been dominated by the past. The development of CNC machine appears to extend the direction of the two ends, that is, the development of high-tech and high-function CNC products, and the development of simple and cheap CNC machine tools and manual CNC machine tools with manual and function. Meet the multi-level requirements of production.

In the current general economical CNC lathe, the vertical and horizontal automatic feed motion is driven by the stepper motor servo, which requires two sets of servo systems. In the ordinary lathe, the longitudinal and lateral feed movements are realized by mechanical transmissions that are self-locking with each other, and the two-coordinate linkage function cannot be realized. The exception is the copying lathe, which has a two-coordinate linkage function, which can turn the cylindrical conical surface and the circular arc surface. The oblique contouring movement is controlled by the hydraulic servo control system under the control of the standard model hard master to make the contour feeding corresponding to the longitudinal main feed motion. Thereby the linkage function of two coordinates is realized. Linking the two directions of motion is the standard sample hard master and hydraulic servo control system. In the specific use, it is necessary to consider the accuracy of the hydraulic system such as the standard sample, the reliability of the system, etc. 2, combined with the economical CNC lathe driving method, we get inspired to replace the hard model standard with the soft model NC programming. The working principle of the piece is to adopt a tool holder layout similar to the profiling process, and to control the single coordinate of the tool holder. The two-coordinate linkage of the tool holder is realized, which simplifies the numerical control principle and manually inputs the machining program through the keyboard. At the same time, the original operating handle of the machine tool is retained, which makes the machining operation extremely convenient and has good flexibility. To this end, the idea of ​​developing a manual economical CNC tool holder was proposed. Manual economical CNC tool holder system constitutes a simple 1.

The whole system consists of a CNC tool holder 1 and her 18031 single-chip stepper motor drive source for picking up, the encoder of the spindle letter 4 and the position detecting element for detecting the longitudinal start signal. The machine body consists of. The system modification is carried out on the basis of the original ordinary lathe. The whole modification work is not large. It only needs to be replaced by the small knife holder of the original working bed, and replaced with a special CNC tool holder. It is installed on the small shaft of the machine for picking up. An encoder for the spindle signal; mounted on the bed rail for detecting the longitudinal start signal to produce a longitudinal start signal.

The vertical and horizontal operation handles of the original machine tool are retained, which greatly facilitates the entire machining. The entire CNC tool holder is composed of a knife step body, that is, a mechanical part and a stepping motor, and the stepping motor passes through the transmission screw. Drive the knife holder movement. The installation of the number of tool holders shows that the axis of movement of the CNC tool holder is at an angle to the vertical direction of the workpiece end face. Count 1 哝 擂 1 oil resistance, square 擂, move. The different oblique contouring movements in the different foot contouring process are controlled by the standard specimens, which are realized by hydraulic movement.

The oblique movement of the CNC tool holder is controlled by the soft machining of the part machining program, which is realized by the servo motion of the stepping motor.

The movement of the whole system consists of two parts: the longitudinal automatic movement of the original machine tool and the oblique movement of the numerical control tool holder. The synthetic motion can process the cylindrical conical surface and the circular arc surface.

The longitudinal automatic movement of the main motion and the longitudinal movement of the original machine tool are completely carried out by the main shaft through the hanging wheel and the longitudinal screw opening and closing nut of the hanging box drives the table for longitudinal movement. After being installed on the spindle, it is sent to the microcontroller. At the same time, the longitudinal start signal detected by the Hall element mounted on the bed rail is also sent to the microcontroller. The plus 1 program based on the contour shape of the part is previously input to the microcontroller through the keyboard. After processing by the microprocessor, according to the contour shape of the processed workpiece, a series of pulses are emitted, and after stepping motor drive power is used for power amplification, the stepping motor is driven to drive the numerically controlled tool holder to perform oblique movement corresponding to the longitudinal automatic cutting, forming The contour shape of the workpiece being machined.

It can be seen from the above that the system realizes the two-coordinate linkage for single-coordinate control, and the key is to seek the connection between the longitudinal 6-moving and the oblique movement of the numerical control tool holder. This task is realized by an encoder mounted on the main shaft. How to find a single coordinate control to achieve two coordinate linkage The whole machining process is divided into several passes, which is completely determined by the part processing program.

It can be seen from the foregoing that the processing method and the profiling method are adopted, and the difference is that there is no mold part, but soft, and the mold is replaced by numerical control programming. It can be mountain, it has the simple programming mode such as = characteristic; the machining allowance of the whole part in different contour element segments is very important for ensuring the machining accuracy of the parts.

The whole program can be divided into two main parts of the main motion of the stepper motor movement; the stepper motor and the vertical prong automatic contour matching subroutine.

Throughout the machining process, it can be seen that the contour machining subroutine is repeatedly called repeatedly during the execution of the main program of the infeed.

3 Interpolation principle In the modern 0 numerical control machine tool, the trajectory control mode adopted by the numerical control device can be divided into two categories: reference pulse method; the class is data sampling method. The so-called reference pulse method is to calculate the increment of the single feed pulse of each axis according to the feed ratio of each coordinate axis for each run, and the data sampling method means that the interpolation program runs at a fixed sampling frequency. Obtaining the increment of the coordinate form of the digital form related to the feed rate determined by the feed ratio relationship of each axis in a sampling period. The commonly used algorithm of data sampling interpolation technique is the digital integral of the time division method. Law and direct calculation.

The various interpolation methods mentioned above can be described as various, but one thing in common is that the system to be applied is two or more sets of servo drive systems.

The manual economical CNC tool holder system has a clear and directional movement in the structure, which is composed of the movement of the original machine tool.

Control a stepping motor to achieve two-coordinate linkage, and set its own interpolation algorithm. As any kind of interpolation algorithm, real-time control should be strictly implemented, which requires that its interpolation operation can not be cumbersome. It should be as simple as possible to combine the characteristics of the manual economical rigorous CNC tool holder, and integrate various factors in the selection of crystal oscillator 12 Based on the 8031 ​​milk. The connection calculation method in the data sampling method is called. In spite of this, with the other two coordinates or coordinate control system, the detailed theoretical and sub-inspection arguments can be controlled in real time.

The installation of the CNC tool holder shows that the axis of the CNC tool holder moves at an angle with the end face of the workpiece. The longitudinal movement of the tool holder carriage is driven by the main shaft through the hanging wheel feed box slide box to move the longitudinal carriage. The corresponding longitudinal movement amount per spindle can be read from the nameplate of the feed box. The signal of the cutter is generated by the spindle braider mounted on the spindle chuck, and the shaft is evenly emitted every revolution, and the longitudinal carriage moves the distance from the corpse. When the spindle sends out a pulse of the claw, it is fed and the small longitudinal carriage moves away from this signal. The signal is input to the microprocessor to control the CNC tool holder to move along the 7 axis, and the 7-axis pulse equivalent is set to pulse. Control the number of pulses on the 7 axis with the state.

When machining cylindrical conical surface and end contour, the relationship between him and the claw can be calculated by using the mathematical model, Asin9, when 9=, when machining the cylindrical surface, the tool holder; 7 direction is not fixed; when 0= 9, hour. The end face is processed, and the linear relationship is maintained between 1 and Can; when 0=, 9, the processing cone, the 沁 and the take, maintain a linear relationship.

When machining an arc surface, due to the constant change of its slope, there is no constant proportional relationship between the spindle pulse and the stepping motor pulse. Therefore, the stepping machine pulse frequency is changed during the addition of 1 to make a change. Frequency control.

The method of squatting is to use the string to walk around the arc. 1. The whole 1 trapping process is divided into two parts: coarse interpolation and fine interpolation. Taking the concave arc as an example, the initial value is 9. The slope of the end point of the front contour section is the part, so the key is in the corpse, and the recursion can be used to obtain the first spindle. The first pulse is 7 axis. The number of pulses, fine interpolation is not determined to be an integer, there is a fractional part. The number of steps taken by the stepping motor must be an integer, and the remainder of the previous interpolation is the fractional part, plus the calculation result of the interpolation, and then the sum is rounded, and the rounding result is used as the interpolation. The value is added, and the remainder is reserved for the next interpolation.

After the coarse and fine insert, although there is a small error in each interpolation, the cumulative error will not be greater than 1 pulse equivalent during the entire interpolation process.

The end point discriminates when the number of pulses actually taken by the stepping motor and the total number of pulses in the plus section and the equal time, then the interpolation and the acceptance of the transition 4 are stopped, and the tool holder is used as a breakthrough, and a tool holder layout similar to the 4-profiling process is adopted. In addition, the CNC interpolation method specially proposed and developed is realized. Through the single coordinate control of the tool holder carriage, the vertical and horizontal coordinate linkage of the tool holder is realized. It not only retains the characteristics of the operation of the Pudi machine, but also has the functions of CNC machine tools to process the circular surface of the cone, and replaces the two sets of servo systems that are usually required by the servo system with low-cost and easy-to-learn programming and easy-to-accept processing. Both provide a strong guarantee for the application of the program in machine tool transformation. The manual economical CNC tool holder has obtained the national utility model patent, and the patent ZL95241997.L 1 is bright. Single-chip microcomputer software design technology 1. Beijing Science and Technology Literature Publishing 刁 Lei Xuedong, Zhu Xiaochun. Numerical control principle and system elbow. Nanjing University Press, Nanjing, 3 Wang Huifang. The basic situation of the foreign machinery industry of metal cutting machine tools. Beijing Mechanical Industry Press, 1994.

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