Development of Shaped Screw CNC Grinding Machine and Research on Related Technology

Rotating to achieve the rotation of the workpiece; the table relative to the I machine bed: for the longitudinal flushing'House.Allrights 2 forming grinding wheel truncation calculation and dressing of the shaped screw is the key to the shaping of the grinding wheel, while the grinding wheel is shaped and trimmed The first task is the truncation calculation of the grinding wheel.

The calculation and trimming steps of the profiled grinding wheel of the profiled grinding wheel can be summarized as shown in the process.

The main basis for the calculation of the grinding wheel cut-off shape is the screw helix profile line parameter. The screw type line is the technical secret of the enterprise and usually does not leak to the outside world. It is often provided to the machine tool manufacturer with discrete point data of the spiral surface section or end section. If the grinding wheel truncation is calculated point by point from these discrete data, the calculation workload is large. To this end, these discrete points can be curve fitted with a variety of quadratic curves to reduce the computational effort. The author uses the two arcs that are tangent to each other to fit the points between the points, and uses the double arc spline to fit the curve, that is, the distance from the given data point to the arc is controlled. Within a given error range, the calculation and trimming steps of the special-shaped screw-shaped grinding wheel are difficult to establish. Because it is a transcendental equation, after the numerical solution process processes the discrete data points of the screw line, Obtain a small circular arc segment with end section or axial section tangential to each other. The equation is: end section axial section where: R. is the radius of the arc segment, a is the arc parameter, and L is the number of small arc segments. With these small arc segments as a spiral motion, a segmented screw helicoid equation 17 can be established: where: 0 is the corner and is the spiral parameter.

It can be seen that if Zj=0, the screw end section line equation can be obtained. If Xj=0, the screw shaft section line equation can be obtained. () Calculation of the cutting shape of the grinding wheel The grinding process of the screw surface by the forming grinding wheel is essentially the envelope forming process of the working surface of the grinding wheel to the spiral surface of the screw. Since the working surface of the grinding wheel is a curved surface, if the instantaneous meshing line of the conjugate mesh surface of the rotating surface and the screw helix surface is known, the cross-sectional shape of the grinding wheel shaft can be obtained according to the instantaneous meshing line.

The conditional equation of the two conjugate meshing surfaces is as follows: where: Av is the relative velocity of the two meshing faces at the meshing point, and h is the surface common normal vector at the meshing point. The meaning is that the relative speed of the two conjugate meshing faces in the direction of the common normal at the meshing point is zero.

The normal vector of the meshing point can be obtained from the provided spiral surface equation, and the instantaneous meshing vector of the grinding wheel and the helical surface of the screw can be obtained by substituting (): where: X, Y., Z,. The meshing three coordinate sub-vectors are respectively meshed. From the instantaneous meshing vector equation, the radius value at each section of the grinding wheel can be easily obtained: sometimes it will diverge, and it is difficult to automatically eliminate the invalid solution in the case of multiple solutions. To this end, the author used the following method in the calculation of the grinding wheel truncation: as shown, using a set of parallel planes perpendicular to the axis of the grinding wheel to intersect with the spiral surface of the screw, the plane and the spiral can be obtained in each plane. The face intersection line, when the grinding wheel and the screw center distance A are given, can search for the smallest outer cutting garden whose center is in the plane of the grinding wheel and is tangent to the intercepting line, and the radius of the circle is the plane The radius of the grinding wheel R. By solving this way, the radius of the grinding wheel in one parallel plane can be obtained respectively, and the combination of these radii constitutes the truncation of the entire grinding wheel. The spacing of the parallel planes is determined by the given accuracy. This algorithm avoids the difficulty of solving the instantaneous meshing line, and the calculation process is fast, stable and reliable.

It can be seen from the calculation process of the grinding wheel truncation that the cutting shape of the grinding wheel is related to the installation angle P and the center distance A. If the value of the 卩 and A changes, the cutting shape of the grinding wheel also follows the change (). When P=0, that is, the grinding wheel axis and the workpiece simplify the mechanical structure of the screw grinding machine, which is beneficial to improve the rigidity of the machine tool. Sanding Xi 1 The above-mentioned grinding wheel truncation analysis method 0 is lower than the lish low machine tool cost in practical application, the condition is the screw End section profile line curvature. The radius should be positive and cannot be negative, ie the end section profile cannot have a concave shape. For example, a co-rotating twin-screw extruder screw profile can meet this requirement, allowing grinding without moving the wheel angle.

After the screw-cut forming wheel is calculated, the dressing of the grinding wheel is no longer a problem. Using the arc-shaped diamond roller as the dressing tool of the grinding wheel, according to the calculated trajectory for two-dimensional interpolation movement, the required grinding wheel forming working surface can be obtained. The requirement is that the radius of the dressing roller should be smaller than the cutting shape of the grinding wheel. Minimum radius of curvature.

3 Control system composition and function control system is the core of CNC machine tools. The screw grinder control system developed by the author is composed of general CNC system and PC microcomputer. The PC microcomputer is loaded with the special software module for screw grinding calculation control developed by the author. The main functions of the software module include: 1 user parameter input, including screw diameter, lead, number of heads, right and left direction, profile parameters, grinding wheel installation angle, etc. Parameter; 2 Grinding wheel truncation calculation, automatically calculate the grinding wheel truncation and grinding wheel dressing trajectory according to the parameters of the grinding screw and the diameter of the grinding wheel; 3 The NC program is automatically generated, and the system automatically calculates the grinding cycle quantity according to the user setting, and automatically generates the grinding cycle number and generates Grinding and grinding wheel dressing NC program; 4 control parameter setting, including machine coordinate origin and dressing wheel coordinate point setting, screw grinding point and bearing setting, grinding amount and dressing amount setting, grinding wheel and dressing wheel parameters , DNC communication and other parameter settings. In addition, the module also has functions such as machining simulation and screw grinding line correction.

The main features of the special software module for calculation control developed by the author are the timely calculation of the cutting of the grinding wheel under variable parameters and the automatic generation of the numerical control program. The grinding process of the screw grinding machine is controlled by the DNC interface.

The working interface of the control software module is as shown.

The dedicated control software module user interface 4 concludes that the automatic grinding of the screw and the automatic dressing of the grinding wheel are successfully achieved with three or five AC servo control axes. The double-arc spline is used to fit the discrete screw-shaped line data points, and the truncated shape of the special-shaped screw grinding wheel is obtained through a series of discrete parallel sections to avoid the use of the module to realize the truncated shape of the grinding wheel under variable parameters. The timely calculation and automatic generation of the NC program control the grinding of the screw grinding machine through the DNC interface.


High accuracy, full penetration welded, sealed construction with three parts welded can be used for in marine project, is able to float.

For example, cooperating and connecting with other marine structures (vessel, box anchor...)

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The construction is to be built according to the drawing with rules of good workmanship.

All the welding seams are waterproof.  


All fabricated steelwork used in the construction of the pipe line will be to manufacturing standard of UniSite or other classification society.

All materials proposed will be selected to comply with the latest Health and Safety Rules.

Paint systems for hull protection will be of the highest quality (Hempel, Inter, Sigma, Jotun)


All welding will be performed in accordance with drawing and standard and UniSite experience and all welding will be continuous and full penetration.

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High accuracy(ISO2768, ISO5817, ISO13920)


Q195-Q345, S235JR-S355J2G3 or other materials


All the welding seams are waterproof.  


As per drawing

Out diameter


Wall thickness






Special capacity

Floating, Connection


Sa2.5 blasted and two or three layers painted with highest quality


as per clients' requirements


material, construction, dimension, welding seam, non defective test, paint inspection


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Besides above the general specifications, we can also supply some specific floating pipes and other similar steel structure as clients' requirements.


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