Showing papers on "Machining published in 1983"

Laser machining apparatus

Abstract: Improvement in a laser machining apparatus using, in combination, a machining laser oscillator (101) and a device (110) for supplying auxiliary energy such as a plasma. The invention is characterized in that the auxiliary energy generated by the auxiliary energy supply device is applied to a position on a workpiece (118) at a small distance from a point thereof irradiated by a machining laser beam. In a preferred embodiment, the auxiliary energy supply device (110) is attached to a turntable (113) so that the auxiliary energy is constantly applied to a position on the workpiece preceding the point thereof irradiated by the laser beam, in the direction of the machining progress. Alternatively, the arrangement may be such that the auxiliary energy is applied to the surface of the workpiece opposite to the surface irradiated by the laser beam. Such an arrangement of apparatus makes it possible to improve the machining efficiency and accuracy, and simplify the structure of the apparatus as a whole, resulting in a reduction in the number of machine troubles. In order to further improve the machining efficiency, in a preferred embodiment, the portion being machined may be supplied with abrasive grains, sprayed with high-pressure working liquid, or supplied with working liquid provided with ultrasonic vibrational energy. An automatic mechanism for adjusting the focal point of the laser beam may also be provided.

Adaptive control for machine tools

Abstract: An adaptive control for a turning machine which adjusts the machining rate to maintain the actual horsepower dissipated at the cutter tip at a constant set point despite changing workpiece and cutter parameters. The machining rate is adjusted by control of the machine drive and tool feed to achieve required SFM and IPR values, respectively, within maximum and minimum SFM and IPR limits. "Speed" and "Axis" override controls are also provided. The rate of adjustment of SFM and IPR to a deviation of the cutter tip horsepower from the set point is inversely proportional to the measured system gain so that the response factor of the control loop is maximized. The commanded machining rate of (SFM) (IPR) product is periodically determined by estimating the actual machining rate and multiplying the estimate by the ratio of the set point to the cutter tip horsepower. The cutter tip horsepower is determined by subtracting the electrical loss, mechanical friction loss, and the net power required for net acceleration of the drive, from the measured electrical power supplied to the drive motor. The cutting efficiency is monitored to perform tool wear, tool breakage, and tool protection functions. The adaptive control also has soft engagement and soft disengagement functions for initiating and terminating the adaptive machining process.

Method of inputting machining information to a machine tool numerical controller and apparatus therefor

Abstract: A numerical controller for a machining center comprising a microprocessor, which selectively executes an automatic programming function and a numerical control function. The microprocessor selectively displays on a CRT display unit various information which instructs an operator to input machining information regarding the blank and finished shapes of a workpiece and the mounting position of the workpiece on a work table. The operator inputs the machining information with a key board-type data input device in response to the information displayed on the CRT screen, and the machining information is stored in a data storage device. Based upon the stored machining information, the microprocessor then displays on the CRT screen the blank shape and the finished shape of the workpiece so that the operator can observe if the machining information has been correctly input. Unless modification of the stored machining information is required, the microprocessor prepares the numerical control (NC) program based upon the stored machining information. The microprocessor, in response to a machining start command, executes the numerical control function and controls the operation of the machining center in accordance with the NC program.

Machinability of Engineering Materials

Abstract: 1 The Concept of Machinability.- 1.1. Introduction.- 1.2. Definition of Machinability.- 2 Fundamental Aspects of the Machining Process.- 2.1. Mechanics of Metal Cutting.- 2.1.1. Chip formation.- 2.1.2. The effect of changes in cutting parameters on cutting forces.- 2.1.3. The effect of changes in cutting parameters on cutting temperatures.- 2.2. Tool Wear.- 2.2.1. Mechanisms of wear.- 2.2.2. Types of wear.- 2.2.3. Relationship between tool wear and time.- 2.2.4. Relationship between tool wear and cutting conditions.- 2.2.5. Relationship between tool life and temperature.- 2.2.6. Tool life criteria.- 2.3. Surface Finish.- 2.3.1. Introduction.- 2.3.2. Mechanism of surface finish production.- 2.3.3. Factors which influence surface finish production.- 2.4. Chip Formers.- 2.4.1. Mechanics of chip formers.- 2.4.2. Effect of cutting conditions on chip forming.- 2.4.3. Effect of chip formers on cutting forces.- 2.4.4. Effect of chip formers on tool wear.- 2.5. The Action of Cutting Fluids.- References.- 3 The Assessment of Machinability.- 3.1. Types of Machinability Test.- 3.2. Short Machinability Tests.- 3.3. Non-Machining Tests.- 3.3.1. Chemical composition tests.- 3.3.2. Microstructure tests.- 3.3.3. Physical properties tests.- 3.4. Machining Tests.- 3.4.1. The constant pressure test.- 3.4.2. The rapid facing test.- 3.4.3. Tapping tests.- 3.4.4. Degraded tool tests.- 3.4.5. Accelerated wear tests.- 3.4.6. High-speed-steel tool wear rate test.- 3.4.7. Taper turning test.- 3.4.8. Variable-rate machining test.- 3.4.9. Step turning test.- 3.5. Combination of Machining Parameters.- 3.6. Machinability Assessment for Processes Other than Single Point Turning.- 3.6.1. Introduction.- 3.6.2. Machinability assessment in drilling.- 3.6.3. Machinability assessment in milling.- 3.7. Machinability Assessment Relating One Process to Another.- 3.8. On-Line Assessment of Tool Wear.- References.- 4 Tool Materials.- 4.1. Historical Background.- 4.2. Requirements of Tool Materials.- 4.3. High-Speed Steels.- 4.3.1. Introduction.- 4.3.2. Structure of high-speed steels.- 4.3.3. Heat treatment of high-speed steels.- 4.3.4. Applications of high-speed steels.- 4.4. Cemented Carbides.- 4.4.1. Introduction.- 4.4.2. Classification of cemented carbides.- 4.4.3. Structure and properties of cemented carbides.- 4.4.4. Mixed cemented carbides bonded with cobalt.- 4.4.5. Coated cemented carbides.- 4.4.6. Titanium carbide cemented carbides.- 4.5. Cast Cobalt Alloys.- 4.6. Ceramic Cutting Tool Materials.- 4.7. Diamond.- References.- 5 Workpiece Materials.- 5.1. Introduction.- 5.2. Ferrous Materials.- 5.2.1. Carbon steels.- 5.2.2. Free-machining steels.- 5.2.3. Stainless steels.- 5.2.4. Cast irons.- 5.3. Titanium Alloys.- 5.4. Nickel-Based Alloys.- 5.5. Aluminium Alloys.- 5.6. Magnesium and its Alloys.- 5.7. Copper and its Alloys.- References.- 6 The ISO Machinability Test.- 6.1. Introduction.- 6.2. Reference Work pieces.- 6.3. Reference Tool Materials and Tool Geometries.- 6.4. Reference Cutting Fluids.- 6.5. Cutting Conditions.- 6.6. Tool Life Criteria and Tool Wear Measurements.- 6.7. Tool Wear Measurement.- 6.8. Equipment.- 6.9. Tool Life Test Procedure.- 6.10. Evaluation of Tool Life Data.- 7 The Effect of Machinability Data on Metal Removal Performance and Economics.- 7.1. Introduction.- 7.2. Criteria of Performance.- 7.3. Economics of Turning Operations.- 7.4. Machining for Minimum Cost.- 7.5. Machining for Maximum Production.- 7.6. Machining for Maximum Profit.- 7.7. Machinability Data Applied to Milling.- 7.8. Reliability of Machinability Data.- Reference.- Appendix 1 Analysis to Determine Cutting Temperatures in Single Point Metal Cutting.- Appendix 2 Analyses for Two Short Absolute Machinability Tests.- A2.1 The Variable-Rate Machining Test.- A2.2 The Step Turning Test.

Adaptive Control in Machining—A New Approach Based on the Physical Constraints of Tool Wear Mechanisms

Abstract: An optimization procedure for adaptive control based on the physical constraints of the machining process is proposed Three different modes of tool failure have been examined and constraints for each mode of failure identified accordingly A mapping procedure has then been used to transform these constraints into a control variable space and obtain a “safe working range” The optimum working conditions are determined in terms of the control variables (cutting speed and feed rate) based on a chosen performance index (metal removal rate, in this case) Also, further consideration of time-varying situations such as tool wear and engage-exit conditions can be included in this formulation Several numerical examples are presented for the identification of the dominant modes of failure, in particular, experimental cases The results are in good agreement with the experimental data available

Monitoring machine tool conditions by measuring a force component and a vibration component at a fundamental natural frequency

Abstract: Methods and apparatus for monitoring, during machining of a workpiece (30,30'), the wear condition of a cutting tool (31,31') having its cutting portion in a structure (32,32') that is held by substantially more massive means (33,33'). A dynamometer (35,35') and filter (36) measure the component of the dynamic force exerted between the tool (31,31') and the workpiece (30,30') approximately in the direction (A,A') normal to the primary cutting edge (34,34') of the tool (31,31') and to the main cutting velocity (V,V') at approximately the fundamental natural frequency of the held structure (32,32') in the same normal direction (A,A'). An accelerometer (37,37'), filter (38), and integrators (39) measure the component of vibration in the tool (31,31') approximately in the same normal direction (A,A') at approximately the same frequency. Data processing equipment (41,42,43) computes the value of a wear indicative function of the ratio of the measured force component to the measured vibration component, and provides a display, adjustment, or other selected type of response (44) thereto. The computed value of the function typically indicates the amount of wear (FW) on the flank of the primary and secondary cutting edges (34,34') of the tool (31,31') during turning, milling, or drilling.

Machining system with operating mode selectors provided in machine controller of each NC machine tool

Abstract: A machining system for controlling the operation of a plurality of NC machine tools with a master controller, which is provided with an operation mode selector in a machine controller of each NC machine tool, and which is suitable for efficiently machining metal molds. The machining system allows the operator to quickly respond to a change in the condition of the production site and progress the machining operation of each NC machine tool only by manipulating the operation mode selectors without changing the machining sequence registered in advance in the master controller according to the production plan.

Wear mechanisms of Syalon ceramic tools when machining nickel-based materials

Abstract: The failure modes and the wear mechanisms operating at the tool faces, when machining Incoloy 901 with Syalon* ceramic tools, have been studied. It was observed that the tool life was controlled mainly by notching at the depth of cut and flank-face wear. A t very high speeds and feed rates fracture failure was also observed. Notching at the depth of cut was the dominant failure mode at slow speeds, and the use of various active and inert atmospheres suggests that it is caused by a chemical interaction between the chip and the tool. At high speeds, tool life was controlled by flank-face wear. The wear-mechanism analyses suggest that attrition, diffusion, and plastic deformation controlled the tool life. At slower speeds, attrition is the dominant wear mechanism, whereas at higher speeds diffusion followed by plastic deformation dominates. Where attrition occurs, either individual Syalon particles or aggregates of them are lifted off the tool faces, whereas with diffusion, transition elements (espe...

A numerical controlled machine tool making intermediate measurements

Abstract: A numerical controlled machine tool apparatus capable of providing intermediate measurement (in process measurement) during the carrying out of a machining process on a workpiece. A spindle of the apparatus, usually used for mounting a machining tool, is also capable of mounting a measuring tool which generates a contact signal when the measuring tool on the spindle is brought into contact with the workpiece. A measuring control unit including a memory is capable of compensating for any deviation that may exist between a center axis line of the measuring tool and the center axis line of the spindle, thereby making the apparatus capable of carrying out accurate measurements and adjusting a machining process based on the result of such an accurate measurement.

Laser beam machining apparatus

Abstract: A laser beam machining apparatus includes a working laser beam for machining a workpiece and a visible laser beam which is made coincident therewith. The coincident laser beams are scanned along the X-Y plane of a surface to be machined by a pair of optical scanners. The movement of the optical scanners is controlled as a function of machine signals indicative of the desired movement of the laser beam and compensation signals indicative of the temperature drift of the optical scanners. A camera detects the instantaneous position of the visible lens as it is scanned along the surface to be machined and generates output signals indicative thereof. The output signals are compared to the machining signals to determine the temperature drift of the optical scanners and the compensating signals are generated as a function thereof.

Hard metal insert body

Abstract: Hard metal insert body as a tool or for insertion at correspondingly loaded places of tools, especially those exposed to frictional and impact loading, for example for machining stone, concrete, ceramics or like materials and also for machine wear parts, is constructed for resistance, with optimum life, to different simultaneous loadings, especially frictional and impact loadings, such that it consists of firmly connected solid parts which are preferably arranged in layers, parts, sections or alternately, to form a unit

Machine for manufacturing universal joints

Abstract: This invention relates to metal cutting and more particularly to machines for manufacturing constant velocity universal joints. A construction is disclosed wherein spherical turning, milling and grinding of the races and grooves of the joint members of a universal joint are performed on common machines without removing the workpieces and the workpieces are held in common workheads. During the machining operations, relative movements between the tools and workpieces are referenced to common axes thereby duplicating the relative positions and movements between the workpieces during actual service. The inventive concept provides a means for achieving consistent product quality and is adaptable to the automated manufacturing of constant velocity universal joints.

Edge cracking in high strength steels

Abstract: A study has been made of the sheared edge ductility of a series of coldroll gage high strength steels. It is found that inclusion shape control is beneficial, especially for steels with tensile strengths ranging from 345 to 550 MPa (50 to 80 ksi). Edge ductility is increased for all the materials when the quality of the edge is improved; this involves removing the heavily coldworked sheared region either by machining, trimming (repunching), or a heat treatment which results in the recrystallization of the edge. Following a heat treatment, the steels with no inclusion shape control have hole expansion values similar to those observed in materials with inclusion shape control before heat treatment. It is suggested that for the steels with the stringer type inclusions, low edge ductility will be exhibited when fracture initiates in the deformed shear edge region and propagates along the inclusionferrite interface. The elimination of this coldworked region makes crack initiation more difficult and, thus, there is greater ductility. A tempering study of dualphase steels suggests that the hard martensite islands play a similar role to the stringer type inclusions in reducing sheared edge elongation. It was also observed that the load to punch out a disc is proportional to both the thickness and the tensile strength of the material.

Method for machining three dimensional contours utilizing a numerically controlled lathe

Abstract: A computing unit (12) produces control signals which, when applied to the control inputs of a conventional numerically controlled lathe (10), cause the lathe cutting tool (60) to be positioned such that contours varying in three dimensions may be realized in a spindle (18) mounted, rotating workpiece (20). The control signals include x and z position signals, defining the position of the cutting tool with respect to the radial (24) and axial (22) axes, respectively, of the workpiece (20), and i and k lead control signals which define the distance traveled by the cutting tool, per revolution of the workpiece, in the radial (24) and axial (22) workpiece axes, respectively. A filtering process (134, 136, 140) operates to delete each control signal having i and k values which are within the x and z tolerence values, respectively, of the immediately preceding control signal, to thereby reduce both the volume of stored data and machining time.