In response to the increasing demand for press tools, a compact and practical CAD/CAM system for progressive dies, one of the most complicated types of press tools, has been developed. The features of this system are: (1) designing can be easily accomplished just by inputting the geometrical data of the strip and die layouts, and (2) CAM information can be directly extracted from the CAD information. In developing this system, a new model for die construction has been determined by studying the design process. An algorithm and data file needed for automatic tool selection and calculation of machining conditions and tool paths have been completed from the data obtained by using this model. To analyze the usefulness, many practical studies have been performed, and it has been found that the total period for design and manufacturing is reduced to about 1/5 the time previously required. This method can also be applied to many other types of press tools, such as compound dies, single dies, and transfer dies.
Vibrations and noises of gears consist of the average component and the fluctuant one. The former is the component which always appears in each tooth meshing. In general, this component consists of the meshing frequency and its harmonics. The latter is the component which fluctuates about the average component and is caused by the error of gears, torque fluctuation, and so on. In this report, the extraction of this average component by using a method of moving averages is described. This method is very effective for extracting the average component of gear noises or gear vibrations. The effectiveness of this method is shown theoretically and experimentally.
This paper describes an experimental investigation of the grinding mechanism in a highwork-feed-rate electrolytic grinding method. An idealized tool consists of a single diamond tool and a copper electrode in substitution for the conductive grinding wheel. The influence of electrolytic action on single diamond cutting force components in SS 41 and Al-Cu-Si alloy are investigated and discussed using the cutting force equations reported in the previous paper. Summary of the results are shown below. (1) Cutting force components consist of both chip formation and ploughing force in the case of single diamond cutting. (2) Cutting force compo-nents in SS 41 decrease in proportion to the increase in the applied electrolytic amount. This may be caused by the reduction of chip formation force due to the decrease in actual cutting depth of cut. Ploughing force and specific grinding force are held constant even by the applied electrolytic action. (3) Cutting force components in Al-Cu-Si alloy also decrease with increase of the applied electrolytic amount. As the applied electrolytic action in this alloy induces the preferential dissolution of hardened precipitation particles, the specific grinding force decreases remarkably, thereby causing a decrease in the chip formation force. Material softening by the preferential dissolution increases the ploughing force. (4) The propriety of the proposed cutting model is ascertained by the experimental study of cutting time in an electrolytic single diamond cutting.
This paper describes a new device which can automatically measure the lead error at the cutting edge of threaded cutting tools such as gear-hobs and taps. Firstly, a new precise main spindle with a precise rotary scale, a new-type photoelectric feeler, and an angular position detector for cutting edge are developed. Secondly, the non-contact-type automatic measuring machine is produced, combining them with a tool makers' microscope, laser length measuring system and a microcomputer. Thirdly, the program for the control of the machine and for the measurement are developed, and the cumulative lead error and the cumulative dividing error of the cutting edge are computed from the detected values by the microcomputer and recorded by a printer or a plotter. Finally, in order to investigate the accuracy of measurement in this machine, the experiments are carried out. The main results are as follows: (1) The precision of measurement for the lead error in the gear-hob is 0.16μm for repeatability in standard deviation. (2) The detective precision for the angular position of the cutting edge is about 10'' for repeatability in standard deviation.
This paper describes the change in the vibration of the teeth in the process occurring the initial surface failures of gear teeth. First, the torsional vibration characteristics are analysed of a gear pair with several profile errors and frictions between the teeth. The maximum of the tooth root stress is found to be desirable for observing the vibration characteristics connecting with the tooth failure. Second, the pitting test is carried out to find the typical change in the maximum of the tooth root stress during the test. The pattern of the typical change is as follows: The maximum of the tooth root stress increases gradually with the number of load cycle, then reaches to the peak because of its decrease due to the pitting of the tooth.
Even when the temperature of the ball screw reaches steady state, the change of its distribution is repeated as the nut goes and returns. In this study, the repeated change is numerically analysed by a difference method on several idealization, where the screw shaft is replaced by a solid cylinder and the nut is replaced by a hollow cylinder. This thermal phenomena is treated as a contact problem between two cylinders. The following results are obtained: (1) The temperature of the screw shaft is higher just around the nut. Therefore, it is expected that the forced cooling of the screw surface near the nut is effective. (2) There is almost no temperature gradient in the radial direction. Therefore, there is a possibility that the heat transfer of the ball screw can be regarded as one dimensional problem.
The various phenomena generated in the machining process are generally recognized for the quality control purposes on the basis of the engineering measurements. However, the skilled machinist perceives the premonitory symptom of the unusual grinding phenomenon by his excellent sense of hearing. The present paper, therefore, was an attempt to devise new monitoring methods which utilize positively the acute sense of the human instead of the customary methods. Our study has led to one very significant conclusion : There is a very strong possibility of the diagnosis of the redress life, because the sensuous value perceived by the human can be rank-ordered and discriminated by means of the technique of pattern classification using fuzzy algorithm.
The purpose of the paper is to theoretically calculate infeed of grinding wheel for forming a cambered workpiece such as roll in traverse grinding. The infeed of grinding wheel has been analyzed considering various residual stock removals, wheel wear, the profile change of cutting surface of wheel caused by wheel wear. Then it is made clear that cambered workpiece can be ground with NC-grinding machine. The distributions of stock removal rate, grinding force and wheel wear rate on cutting surface of wheel are calculated.
The paper is concerned with the increase of endurable pressure in machining of a new lapping wheel named ''Liquid-Bonded Wheel''. The bond strength of this wheel is smaller than that of conventional grinding wheels. But endurable pressure of this wheel becomes high enough to withstand the mechanical shock of bumping to the workpiece and machining by employing some technique as follows. (1) Improving the angular accuracy of the axis of the main spindle of machine. (2) Using finer abrasives for increasing the contact points by unit volume of stacked grains in the wheel. (3) Using combination in still finer grains with the fine grains for increasing the density of the mixture. The wheel employing these technique has the endurable pressure of about 1 MPa in machining. Moreover, packing the vessel uniformly with abrasive grains may be important, for an uneven packing may deteriorate the flatness of the working surface of the wheel, and the flatness may influence the geometrical accuracy of the finished surface of workpiece. The wheel packed uniformly with grains is manufactured by covering the bottom of a mold with some annular plates.
This paper deals with the life of various tools to clarify the machinability and optimum tool materials in cutting of sintered carbons with high hardness. Furthermore, the behaviors of the tool wear are discussed from the view points of cutting forces, chip geometries, surface roughness and vibration characteristics, such as cutting frequency and amplitude in chatter vibration cutting. The obtained results are as follows. (1) The tool is worn by the abrasive action in cutting of sintered carbons. Particularly, CBN and ceramic (black) tool are worn. Sintered carbide (K grade) and sintered diamond tool have a long life in tool materials used. (2) A decrease of the wear rate of the tool relief face in chatter vibration cutting and in increasing of the cutting speed depends on a decrease of the contact number between tool and work and an increase of relief angle, which is varied by vibration characteristics.
Single-point diamonds are used to scratch the surfaces of HP-Al2O3, HP-Si3N4 and S-SiC. When depth of cut is about 2μm, the diamond tips are worn by either the single-plane or the double-plane or the microfracture type. The wear rate of S-SiC is the highest and then HP-Si3N4 and HP-Al2O3 in turn. When depth of cut is larger than 2, um, the adhesion is remarkably severe. The adhered layer has a tendency to become thinner as the scratching speed increases. It exhibits swelling and partly flaking repeatedly in the scratching process.
This paper deals with a reliability analysis for determining an abrasive belt life by the size of wear land formed on the cutting edges. The experiment was carried out under the following conditions: the grinding speed is 480, 960 and 1440 m/min, and the contact pressure is 17, 35 and 50 kPa, respectively. The distribution of the land was measured at the desired grinding time up to 3600 seconds using a new developed instrument. The experiment above was repeated by changing grain size, stiffness and grade of the belt. It was found that the distribution of wear land is fitted to the Logarithmic normal model. The reliability function and the hazard rate of abrasive belt life for quality of surface finish are also derived.
In this paper, tool life in wafer rotation grinding is compared with that in creep feed grinding. Then the trial to improve the tool life is done by means of doing dressing and grinding simultaneously. The main results obtained are as follows: (1) Tool life in creep feed grinding depends on increasing of surface roughness and normal grinding force and changing of outlook of ground surface. And, in this case, it is about 100 wafers of 4 inch size. (2) Tool life in wafer rotation grinding depends on increasing of normal grinding force, and, in this case, it is 10-15 wafers of 5 inch size when dressed by PVAR 600, 60-70 wafers of 5 inch size when dressed by GC 1000 H. (3) Surface roughness and normal grinding force are maintained nearly constant by means of each time dressing and intermittent dressing. And these dressings are done during grinding, so there is no loss time for dressing. Therefore the problem of tool life can be resolved. (4) Wear of grinding wheel by dressing in wafer rotation grinding is nearly equal to that in creep feed grinding.
For the purpose of contributing to the advanced technology of fabricating metal molds and dies with curved surfaces, the computational algorithm has been developed for generating tool paths suitable for high rate machining using the cemented carbide toolings. The software incorporates the high speed algorithm developed by a preceding study of the authors for computing the intersections and checking tool interference among multiple curved surfaces. The prototype CAM system automatically generates the tool paths as the rough cutting tool path, contour line tool path, and scanning tool path which continuously transfer on to the next element surfaces. Cutting tests have been performed by using the prototype CAM system connected to a machining center, and demonstrated the effectiveness of the high speed and high accuracy tool path generation and the real time machining of the curved composite surfaces.