Tool Handle Research Articles

Synchronization of operations in a flexible manufacturing cell: The Petri net approach

Abstract In designing a shop floor controller for a flexible cell, interactions between the different real time, discrete event functions must be established and a computer structure capable of supporting these requirements must be identified. A distributed microprocessor-based architecture is described and a two-level machine tool synchronization structure is presented. The highest level performs the coordination of part flow between machine tools in the cell. The lowest level performs the coordination of a machine tool and a robot (for part, tool and gripper handling). The specification of the machine tool (and robot) functions working as a concurrent and cooperative system is given in terms of Petri nets: a graphical-mathematical technique suitable for representing process parallelism and asynchronism for flexible control of machine tools in a job shop environment.

Robot/Machine-Tool Concurrency and Cooperation: A Petri Net Formulation

In designing a shop-floor controller for a flexible manufacturing cell the interaction between the different real-time, discrete-event functions must be established, and a computer structure capable of supporting these requirements must be identifiedIn this paper, a distributed micro-processor based architecture is described, and a two level robot/machine-tool synchronization structure is presented. The highest level performs the coordination of part flow between machine-tools in the cell and the lowest level performs the coordination of a machine-tool and a robot (for part, tool and gripper handling)The specification of the machine-tools and robot functions working as a concurrent and cooperative system is given in terms of Petri nets: a graphical-mathematical technique suitable for representing process parallelism and asynchronism for flexible control of robots and machine-tools in a job-shop environment.

Tips on the Proper Use of Hand Tools

This article stresses the need for safe handling of hand tools and lists unsafe practices that should be avoided as well as safe practices that should be followed.

PATHSIM, a modular simulator for an automatic tool handling system evaluation in FMS

Abstract The automatic movement of tools, as well as parts, within a flexible manufacturing system is now technically possible. The prospective benefits of automatic tool movement include reduced tool inventories, lower manpower requirements, and an enhanced capability for unattended operation. This report describes a tool for investigating the performance of automatic tool handling systems associated with flexible manufacturing systems. This work uses simulation to describe the prospective systems. In particular, a combined network and discrete event model, written in the SLAM simulation language, is used. The model is of a modular construction, to facilitate its use for different system configurations in the future. The trade-offs between the advantages provided by automatic tool handling and the increased system costs because of the associated hardware are outlined. An illustration of the search for a satisfactory trade-off is made by varying several factors in an example FMS and assessing their effects on system performance.

Implementation of Task Coordinate Servoing System

This short paper describes the outline of a servo system for manipulators, recently developed at the Electrotechnical Laboratory. The servo system is implemented on a high speed micro-computer and capable of performing dynamics calculation and coordinate transformation of the manipulator in a cycle time for the servo (2.5 mili sec.) .Computation algorithms are formalized in vector form, and directly coded into programs, using vector macro language. The programs are expanded into assembly mnemonic form by macro processor. The mnemonic programs are converted into machine code by a cross assembler which runs on a host computer (VAX 11/780) . Then the machine code prograhi is downline loaded onto the realtime micro-computer (MIPROC-16) .In this servo system, controlled variables are arbitrarily chosen, and mode of control for each variable is also arbitrary. We can select the most suitable coordinate frame in order to do a task. For each motion component with respect to the coordinate frame, position, velocity, acceleration, force or compliance can be controlled. Using the servo system, sophisticated tasks such as parts mating or tool handling will be easily performed.

Resilient handles for power tools : Suggs, C.W. In: Ergonomics in Action — From Theory to Practice, Proceedings of the Joint IEA/NES Conference, Oslo, 20–22 Aug 1980, 5 pp

Resilient handles for power tools : Suggs, C.W. In: Ergonomics in Action — From Theory to Practice, Proceedings of the Joint IEA/NES Conference, Oslo, 20–22 Aug 1980, 5 pp

Flexible Manufacturing Systems with Automatic Transport of Tools

Efficiency of flexible Manufacturing systems for unmanned 24-hours machining of workplaces can be substantially improved by Introducing of automatic handling and automatic transport of tools among Individual machining centres and the tool room. This paper describes solution of some serious problems connected with development of unmanned machining centres equipped with high-capacity tool magazines and tool transport equipment. Tools are stored in plastic cells for their protection during long time storing and are handled automatically by N/C handling units., The paper shows examples of developed flexible manufacturing cells and of flexible manufacturing systems under construction with automatic handling and transport of 432 resp. 1440 tools under computer control. New strategy in tool and workplace organization based on described equipment reduces substantially the total number of necessary tools and workplace pallets in highly automated manufacturing systems of non-rotary, box-like workpieces.

Improving counseling through research: The need for an engineering as opposed to a scientific strategy

In the town of Mystic, Connecticut, there is a seaport museum -which reflects great effort on the part of its sponsors to provide an Authentic replica of an 18th century shipping center, with not only a variety of restored ships to visit, but also a number of homes, chandler stores, sailmaker’s lofts, and other elements which went to make up such a community in that era in American history. Among the exhibits is a cooper’s shop at which visitors may observe the work of an experienced artisan, accompanied by an assistant or two, engaged in constructing the wooden casks and barrels which merchants of the day used for the storage and transportation of goods. The manner in which this craftsman works is a marvel to behold. Relying upon a practiced eye, the information provided to him from the feel of wood between his fingers, or the deft handling of a few ironwork tools, this artisan is capable of producing remarkable wooden vessels of extraordinarily symmetric camber, watertight in operation, esthetically appealing, and within an ace of the specified size.

Dynamic response of the hand-arm system to a sinusoidal input

The mechanical impedance measuring technique was used to obtain data necessary to determine the vibration characteristics of the human hand. From this data, by means of a standard systems identification method, the values of the masses, springs and dampers were derived for an equivalent mass-spring-damper system which simulates the dynamic response of the hand. The influence of grip tightness, hand pressure upon the tool handle and arm position on the vibration response of the hand were examined. For normal arm positions used for operating vibrating power tools, the arm position had little influence upon the vibration response of the hand. However, grip tightness and hand pressure upon the tool handle influenced the vibration response of the hand, especially above a forcing frequency of 60 Hz. In the frequency range studied (20–500 Hz) for a specified arm position, grip tightness and handle pressure, the hand-arm system can be modeled as a six degree of freedom system, two degrees of freedom in each of the principle orthogonal directions. With proper restrictions, the hand was modeled as a three degree-of-freedom system, one degree of freedom in each direction. For a specified arm position, grip tightness and hand pressure on the tool handle, the hand response to a sinusoidal input was similar to that of a linear system. The hand impedances were independent of the amplitude of force input to the hand. The results of this investigation yielded information necessary for determining meaningful hand vibration limit standards. To establish acceptable standards, it is necessary to monitor the vibration limit levels as a function of forcing frequency, the tightness of grip and the pressure of the hand on the tool handle. For, even though the vibration levels may decrease with a tighter grip or firmer hand pressure, the amplitude of the force transmitted through the hand may increase, resulting in an increased probability for injury.

A study on the human factors in shape and size of grouping portion and in position of gravity center of hand-made folk-tools

A half century or more ago in our country, almost tools for domestic, farmer's or wood-craft use were made by hand, fitting shape or size to user's hand or body for the easy use.These hand-made folk tools seems to have much value when we project the spot light of ergonomic aspects.The hand-made folk-tools are, however, rapidly extincting especially from the Second World War, so that we searched them in several local museums or in remote districts mainly in South-Western Japan and collected the measurements of size, shape and weight of 853 hand-made tools and also photographed them.In the present paper, we deal with the shape and size of grasping portion, and correlation between their figures.The results are as follows: 1) The vertical section of grasping, generally draws, a circle or an ellipse. (It's vertical length is larger than horizontal one.) 2) Concerning more productive farmer's and wood crafter's tools, the size of grasping portion measures 20-35mm in horizontal diameter, 25-40mm in vertical diameter, the girth is 85-115mm. 3) There is a significantly high correlation between the tool's handle length and it's position of the center of gravity.

DEGENERATIVE COLLAGENOUS PLAQUES OF HANDS

To the Editor: I would like to comment on several points in regard to the article on Degenerative Collagenous Plaques of Hands published in the February issue ofArchives of Dermatologyby Drs. Ritchie and Williams. Since the publication by Dr. Burks and associates 1 several other reports have appeared. 2-4 Professor Oswaldo G. Costa devoted a chapter to this subject in his book on Acroceratoses published in 1962, and in a recent article Kocsard 5 reported 15 cases. These peculiar palmar lesions occur predominantly in individuals whose professions require tool handling. Five of Drs. Ritchie and Williams' patients were farmers. In ten instances in Dr. Kocsard's series (seven right handed and three left handed individuals) the lesion was confined to the hand used for handling tools. Kocsard concluded that chronic pressure exerted by holding the various tools of trade is the main etiological factor leading to the formation of

Percy Williams Bridgman, 1882-1961

On 24 October 1961 a service was held at the Memorial Church in Harvard Yard to honour the memory of one whose entire professional career was spent at the University, who was for nearly half a century a member of the faculty and who, in a wider sphere, achieved distinction as an experimental physicist, a philosopher and a bold and original thinker. The addresses given on this occasion by several of his colleagues and friends depict a man of unusual stature and of many remarkable gifts. Percy Williams Bridgman, the only son of Raymond Landon Bridgman and Ann Maria Williams, was born in Cambridge, Massachusetts, on 21 April 1882. His father was a journalist by profession, a social and political writer and a lively and ready debater. The family circle was a united one, providing that stable and secure background against which children find freedom to develop according to inclination and ability. In his schooldays, which were spent at Newton, Percy appears to have been an average boy, somewhat shy, keenly interested in sports and games and a good chess player; but it was also remarked that he had, without any need for close application, little or no difficulty in keeping abreast of his school work. He entered Harvard College in 1900, graduated with an A.B.Summa cum laudein 1904 and obtained his A.M. the following year. He had from the first shown ability as an experimentalist, a real artistry in the handling of machine tools and in glass manipulation and a great capacity for intensive work. His interests lay primarily in the field of physics and after graduation he required little persuasion to stay on at College to undertake research in the Jefferson Physical Laboratory. His imagination had early been aroused by the classical work of the great French physicists Cailletet and Amagat on the properties of fluids at high pressures and he resolved to extend their researches into those higher ranges of pressure at which new phenomena might be expected to occur.

Tool Handles and Control Levers of Machines

In order to avoid the production of stigmata on the hands of workmen who frequently use tools and the control levers of machines it is necessary that their shapes should correspond to the following criteria: The strain caused during the operation of the tool or control lever must be minimal in relation to the work performed. The tool or control lever must be constructed so as to be fully suited to the work for which it is required; operations carried out by means of the tool or lever must facilitate the work. When tools or control levers are used throughout a shift it is necessary that their shape be adapted not only to the type of work performed but also to the frequency of use. Tools and control levers should be so constructed that holding or pressing them does not call for the excessive expenditure of energy and they must not cause overburdening of the small muscles of the hand or forearm. The shape of the handle of the tool or lever must be such that the development of callosities, deformities of joints or other working stigmata are prevented.

ウラン工作用フードについて

Special hoods for machine tools, such as lathe, grinding cutter and bench drill, are designed for machining natural uranium metal and these tools mounted with hood are used in metallurgy laboratory of Japan Atomic Energy Research Institute. The hoods mounted onto tool should be well ventillated to avoid contamination. Handling of tool is modified to be adequate for remote controlling for the purpose of minimizing the chances of opening the hood during operation, and to make the tool to be operated by machinist without any difficulty in spite of this modification. Collection of uranium chips contained in coolant is done in a filter vessel which is specially designed for easy taking out chips from the vessel, and transporting them to waste disposal plant. These are the main points which were considered in the design of special hoods for machining natural uranium metal. Experiences and operating data on these tools are also reported in this paper.

Identification of Indian Timbers

Two leaflets have been issued by the Forest Research Institute(Pub. Forest Research Inst., Dehra Dun), on “How to Identify Timbers”, Nos. 21 and 25 (Utilisation). The present War, as was the case with the War of 1914-18, has made a great demand on the timber resources of India. As the demand increases, many new or little-known timbers are being placed on the market. Considerable confusion in identity has supervened, causing perfectly good timbers for the purpose in view to fall into disrepute owing to the substitution of inferior ones. This fact has become well understood by the Defence and Supply Departments which handle timbers, and many inquiries on the subject have been put to the Institute. Leaflet (Part 1) No. 21 gives some general information on the subject of identification of timbers, well known to students of the subject. Leaflet (Part 2) No. 25 is more specialized, dealing with the identification of timbers for “Helves and Tool Handles”. The leafletgives a key for the field identification of certain timbers for tools, the demand for which in ever-increasing numbers, as is well known, has become world-wide. Short anatomical descriptions of the timbers mentioned as suitable for the purpose are included.

Resistance of Wood to Impact Loads

FOR most of the uses to which timber is put, reasonably good resistance to impact is an advantage; for many uses, such as aircraft construction, sports goods, or tool handles, it is an overriding requisite. Its measurement is, therefore, an important part of the routine testing of timber. Since conditions of service as regards this property are seldom, if ever, known with exactitude, and since, moreover, the size and shape of the member receiving the impact bear an important but undefined relationship to its resistance, the laboratory tests for the property are essentially empirical. The resulting figures from such tests in themselves mean little; they cannot be translated into design figures as are, for instance, modulus of elasticity or maximum compressive strength; and their value lies almost entirely in their use for comparisons. As with most empirical tests, one of the essentials is that the character of the test, i.e. test‐piece and testing conditions, shall be rigidly defined and adhered to. Unfortunately there are in more or less common use in the various timber testing laboratories several different methods of measuring impact resistance and the lack of a universal standard impact test is a serious drawback to the usefulness of the results, since one of the greatest advantages of the standardized test, viz., the interchange‐ability of results between one laboratory and another, is at once nullified. It is hoped that when circumstances permit the interested research institutions will take up the study of impact testing and agree upon a uniform standard test.

Grouping Pupils for Acceleration

Previous articleNext article FreeGrouping Pupils for AccelerationH. H. RyanH. H. Ryan Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Elementary School Journal Volume 24, Number 1Sep., 1923 Article DOIhttps://doi.org/10.1086/455459 Views: 14Total views on this site PDF download Crossref reports no articles citing this article.