The selected sub-system is the laser accelerometer for defining a lathe cutter position. This is required for the automated guidance of a lathe, and better calibration and precision of the cutter and chuck positions. (Penrose, 2005) The mentioned accelerometer will be intended for the following actions:
- Defining the position of the cutter and chuck, and further adjustment of their positions in accordance with the given parameters
- Simplify the process of calibrating the lathe regulators
- Improved turner’s safety. If the position of the cutter changes, and that is not stated in the program, the signal from the accelerometer will be interpreted as the signal for urgent lathe stop.
- Decrease the percentage of spoilage
General
The key purpose of the accelerator is to control the position of the lathe cutter and chuck and define the proper cutting angle, considering the optical tilt angle.
Assembly
The general algorithm of the assembly is as follows:
The optical part is mounted on the cutter, and chuck is set to the initial position. This is needed for more accurate and precise calibration. The following step is an assembly of the wired connections and assembly of the fixative bails. The control wires are joint to the position control scheme, and power wires are connected to the electric scheme of the lathe. The location of the wires and fixative bails should not prevent the free movement of the cutters, and should be considered by qualified engineering personnel.
Function and Performance
The accelerometers were installed to define the initial position of the chuck and cutter, and then perform the calibration. This may be performed in manual or automatic regimes. The test program will define the accuracy of the calibration and will be able to perform the necessary tests for defining the motion smoothness of the cutter, as well as the positioning accuracy. If some errors are logged, the program will test the calibration process and may ask to repeat the calibration.
Parameters Adjustment
There are four key parameters that are regulated:
- Sensitivity. This is regulated in accordance with the necessary precision level. Higher sensitivity decreased the speed of a cutter, as the program will have to perform more tests.
- Zero shift. This parameter is used for calibration, and calibration check.
- Random walk. Deflection of the indicator from the zero shift. This is regulated automatically
- Nonlinearity. Depending on the cutting requirements, this parameter defines the position of the cutter and chuck depending on the initial position of the detail or a perform.
Interface
The interface of the regulating software is offered for several platforms, and includes all the necessary parameters for installation, calibration, and work. Parameters may be adjusted in metrical and US systems, and may be interpreted by the software pack. The program operates with the 3D models of the required details, and performs all the necessary calculations for controlling the cutter. Initial installation and calibration parameters are decrypted with an access password, and can not be changed by a non-qualified employee.
Environment
The laser lens should be kept under protection cover. This will protect it from dust, cutting chip, unintentional touches, and other contaminants that may violate the work of the accelerometer. The installation of components and wires, as well as integration to the motion control scheme, and further service works, should be performed in latex gloves, and with deenergized schemes.
Material Appraisal
The offered PDS is based on the key requirements for the laser systems. Therefore, the materials that are used for manufacturing the system are featured with the increased endurance, and lowered weight. In accordance with the material assessment offered by Holzapfel (2003, p. 156):
It is clear that the output of any useful design system should be a specification detailing the way in which the product is to be made, and the standard to which it is to be manufactured. Such a specification will take into account the company’s manufacturing capability, the relative performance of candidate materials, the behaviour of the market and many other technical and commercial factors.
Therefore, it should be stated that the actual requirements for the system design are defined by the idea for a product. Considering the fact that the system should be effective, it should be also adapted for the environment, hence, the materials used for the accelerometer system fulfil the basic requirements stated by ANSI. (Murray, 2005)
The market of high precision systems experiences the needs that are evolved in accordance with the product opportunities and capacities. Therefore, while the accelerometer offers high precision and endurance, the manufacturing standards will be shifted to higher precision. (Wasim ad Raouf, 2005) Additionally, the key requirements associated with the material standards and the following appraisal will involve the idea of the increasing complexity and design aimed at minimization of the construction. (Wilson and Linscott, 2000)
The material appraisal is closely linked with the values of standards attributed to the given class of systems. Hence, as it is stated in The Open University report (2001, p. 451):
In addition to being the facilitator for standards, it is also the responsibility of the ISO to establish the standards. The standards that the ISO is interested in establishing are meant to ensure desirable characteristics of products and services. This includes factors like quality, environmental friendliness, safety, reliability, efficiency, and interchangeability. It is the responsibility of the manufacturer to establish these standards within the organization.
Therefore, the materials used for the system should correspond the key manufacturing standards. This will increase the value of the system, however, if other materials are used, the characteristics of the system may change depending on the material. In fact, it is recommended that compound carbon-filled plastic materials should be used for the body, and monolith polycarbonate for the lens cover. In fact, sapphire glass may be used instead; however, this will increase the cost of the system by 5%. As an alternative to carbon body, titanium alloys may be used. It is featured with the increased cost of the system, and this will increase the danger of electrostatic damage of the laser system.
Manufacturing Process
The manufacturing of the proper polycarbonates for the lens cover is associated with essential difficulties, as the environmental requirements and restrictions forced the manufacturers to develop non-phosgene ways of producing to polycarbonates. This increased the cost of the material by 20%, however, made it 10% more durable, and 5% more transparent (Parvin and Williams, 1999). As Howdeshell and Peterman (2003, p. 1184) emphasize: The interfacial process uses a chlorinated solvent such as methylene chloride which is subject to exposure limits. There is also an economic penalty in that the chlorine content of phosgene is wasted and converted to sodium chloride. The problem of achieving adequate contacting of solid BPA with gaseous phosgene was solved leading to the current interfacial polymerisation process. Here, alkali salts of BPA in aqueous solution are phosgenated in the presence of an inert solvent.
Sapphire glass for the cover is made from pure sapphire boules. Then these are sliced and polished. This materials is more durable to pressure and tension, however, if all the installation requirements are met, there is no need to replace polycarbonate cover with sapphire glass one.
As for the body materials, carbon-filled plastic is cheaper to produce, and the manufacturing process involves filling of the polymer fiber with carbon particles. This requires form for creating the necessary shape, and the compound. Ismail (2008, p. 220) described this process as follows: There are two ways to apply the resin to the fabric in a vacuum mold. One involves mixing of the two-part resin and further applying before being laid in the mold and placed in the bag. The resin induction system: the dry fabric and mold are placed inside the bag while the vacuum pulls the resin through a small tube into the bag, then through a tube with holes or something similar to evenly spread the resin throughout the fabric.
High quality titanium alloys are produced in vacuum environment, (Vydehi, 2006) and should be covered with an isolating material in order to prevent electro-static damage of the scheme that is inserted inside.
In general, there is no need to use more expensive materials as the system is not subjected to extreme temperatures, tension, or humidity. Otherwise, it is not recommended to use the lathe systems in such environments. Polycarbonate, and carbon filled fiber are regarded as the most suitable materials for the laser accelerometer.
Reference List
Holzapfel, W., Mahdavi, N. 2003. Inertial Grade Laser Accelerometer Practicability and Basic Experiments. XVII IMEKO World Congress, 2003, Dubrovnik, Croatia.
Howdeshell, K.L., Peterman P. H. 2003. Bisphenol A is Released From Used Polycarbonate Animal Cages Into Water at Room Temperature. Environmental Health Perspectives 111 (9): 1180–1187.
Ismail, N. 2008 Strengthening of bridges using CFRP composites. Beijing, 217-224.
Murray, T. 2005. A Conceptual Examination of Product Design, Appropriate Technology And Environmental Impact. Hanser Gardner Publications.
Parvin, M., Williams, J. 1999. “The effect of temperature on the fracture of polycarbonate”. Journal of Materials Science 10 (11): 1883.
Penrose, R. 2005. “17.4 The Principle of Equivalence”. The Road to Reality. New York: Knopf. pp. 393–394.
The Open University (UK), 2001. T881 Manufacture Materials Design: Block 1: The design activity model,. Milton Keynes: The Open University.
Vydehi A., J. 2006. Titanium Alloys: An Atlas of Structures and Fracture Features. CRC Press.
Wasim, A. K., Raouf, A. 2005. Standards for Engineering Design and Manufacturing (Dekker Mechanical Engineering). CRC Press.
Wilson, R., Linscott, J. 2000. The New Manufacturing Standard. Hanser Gardner Publications.