1 - Automatic Tool Changer ( group : manufacturing )
previous definition
A variety of machining opertaions means that a variety of cutting tools required. The tools are contained in a tool storage unit that is integrated with the machine tool. When a cutter needs to be changed, the tool drum rotates to the proper position, and an automatic tool changer (ATC), operating under part program control, exchanges the tool in the spindle for the tool in the tool storage unit. Capacities of the tool storage unit commonly range from 16 to 80 cutting tools.
(Groover M.P., Automation, production systems, and computer-integrated manufacturing, Ed. 3rd, p. 388)
new definition
A typical Automatic Tool Change system may have a double swing arm, one for incoming tool, another for the outgoing tool. It will likely be based on Random Memory selection, which means the next tool can be moved to a waiting position and be ready for a tool change, while the current tool works. This machine feature, always guarantees the same tool change time. The typical time for the tool changing cycle can be very fast on modern CNC machines, often measured in fractions of a second.
( CNC programming handbook, Smid P., pp96,97 )
2 - Feature Detection ( group : software technology )
previous definition
Algorithms used for feature detection normally vary with the different feature representation schemes adopted in the feature libraries. Nevertheless, specific tasks in feature detection may include the following (although it is not necessary to have all of them included in a system),
• re-constituting (re-constructing) the geometric model topologically and/or geometrically;
• searching the database to match topologic/geometric patterns with those in the feature library;
• extracting detected feature(s) from the database;
• completing the feature geometric model;
• analyzing and/or re-constructing features.
It is noted that most feature detection techniques are based on the depression-oriented approach, and they largely depend upon the different feature representation schemes employed. There is a number of feature detection techniques developed. They are; (a) graph-based method; (b) syntax-based method; (c) rule-based method and (d) techniques for recognizing feature from CSG models.
(Xun Xu, Integrating Advanced Computer-Aided Design, Manufacturing, and Numerical Control:Principles and Implementations, p.92)
new definition
The goal of feature detection is to identify markers on the user's body accurately. Some interference parts whose color is similar to the markers including background regins and user's body might cause difficulty in detecting desirable markers. Traditional marker detection algorithm is improved in out application to ensure that all the markers are captured and no other region is mistaken as markers. Traditional methods dealing with marker detection problems mainly use color as the key to detect markers. If markers are green, for example, then pixels whose RGB values are within the range of green are regarded as where markers are located. However, some constraints in the real environment prevent traditional ways from achieving a satisfactory result including complex background, change in marker color due to change of lightening, or some regions of human body. (Jeschke S., Liu H., Schilberg D., Intelligent robotics and applications : 4th International Conference, p127)
3 - Direct Clustering Algorithm ( group : manufacturing )
previous definition
The alghoritmic procedure is as follows;
Step 1. Calculate the total number of positive cells in row wi,
Step 2. Calculate the total number of positive cells in row wj,
Step 3. For i=1 to n move all columns j, where Mij=1, to the right, maintaining the order of previous rows.
Step 4. For j=m to 1 move all columns i, where Mij=1, to the top, maintaining the order of previous columns.
Step 5. If the current matrix is the same as the previous matrix, stop, or else go to step 3.
(Computer Aided Manufacturing, 2nd Edition, Chang T.C., Wysk R.A., Wang H.P., 1998 Page: 503)
new definition (better)
This method was devised by Chan and Milner (1982). Directh Clustering Algorithm is a heuristic technique of forming machine component cells from a 0-1 machine component matrix. The ones are consisdered the positive cells and the zeros are the negative ones. The direct clustering algorithm goes through the matrix sequentially moving the rows with the leftmost positive cells on to the left of the matrix. The technique is again a logical way of forming a block diagonal form from machine component incidence matrix. This method allows for more flexibility in the size of the problem. Furthermore, the sensivity of the ROC algorith to the initial matrix is eradicated because: DCA initates the procedure by counting the number of positive cells instead of depending on intuition. The solution converges very quickly and uses a progressive procedure. Procedure used in DCA algorith is explained here.
1.Count the number of 1's (operations) in each row and column
2.Rearrange columns in the descending order of magnitude. i.e., the column with highest value of 1's sholud be on the left and column with lowest value of 1's should be placed on the right. Similarly, rearrange rows in the ascending order such that row with lowest number of 1's should be on the top and row wirth highest number of 1's should be placed at the bottom.
3.Start with the first column of the matrix. Pull all the rows with 1's to the top to form block while considering 2nd and subsequent columns, ignore any row with 1's already in the block. From a new block with rows having 1's not in the block. Once a row is assigned to a block, do not move it. Henge, it may not be necessary to go through all the columns.
4.If the previous matrix and current matrix are same, go to 7 else 5.
5.Start with the first row of the matrix and pull all the columns to the left.
6.If the previous matrix and current matrix are the same, go to 7 else 2.
7.Step.
(Parashar, Cellular Manufacturing Systems: an Integrated Approach, pp68,69)
4 - Hydroforming ( group : manufacturing )
previous definition (better)
Hydroforming is similar to the Guerin process; the difference is that it substitutes a rubber diaphragm filled with hydraulic fluid in place of the thick rubber pad.Thşs allows the pressure that forms the workpart to be increased to around 100Mpa thus preventing wrinkling in deep formed parts.In fact, deepr drawss can be achieved with the hydroform process than with conventional deep drawing.This is because the uniform pressure in hydroforming forces the work to contact the punch throughout its length, thus increasing friction and reducing the tensile stresses that cause tearing at the base of the drawn cup.
(M.Groover. Fundamental of Modern Manufacturing,third edition
page 461)
new definition
Hydroforming is a process that makes use of a hydraulic pressure to improve the basic deep drawing process. The fundamental parts of the tool for a hydroforming process include a punch, a blank holder and a pressure chamber with a rubber diaphragm that seals the liquid in the chamber. The draw ratio achievable in the hydroforming is high (values of about 3.2 are reported in literature), very little thinning occurs and asymmetrical shapes can be drawn.
(D. T. Pham,E. E. Eldukhri,A. J. Soroka, Intelligent production machines and systems: 2nd I*PROMS Virtual Conference,p241)
5 - Orbital Cold Forging ( group : manufacturing )
previous definition
This process forms a cold metal slug between two dies with the upper moving in an arbital motion. This upper die motion creates a high degree of deformation with realtivly little force. By means of the orbital motion , the forming force is concentrated in a small area of the upper die. The orbital angle is normally about 2 degrees . This motion results in progressive forging to final shape , usually in 10-20 cycles and 5-10 seconds.
(Modern manufacturing processes ; James A. Brown , pg137 ; First Edition)
new definition (better)
Orbital cold forging is a deformation metal forming process. In orbital forging the workpiece is subjected to a combined rolling and pressing action between a falt bottom platen and a swiveling upper die with a conical working face, instead of a direct pressing action between two flat platens. The cone axis is inclined so that the narrow sector in contact with the workpiece is parallel to the lower die. As the cone rotates about the cone apex, the contact zone also rotates. At the same time, the dies are pressed toward each other so that the workpiece is progressively compressed by the rolling action. Press loading is appreciably less than that of conventional upsetting because of the relatively small area of instantaneous contact.
In orbital forging, the friction is reduced substantially and metal can flow much easier in a radial direction (rolling friction instead of sliding friction). The maximal stress is only slightly higher than the yield point. Since the contact surface and the friction are much smaller in orbital forging than in conventional forging, the force required for forming is also much lower. The orbital forging process offers the following advantages:
-Elimination of heating equipment and related energy consumption
-Increased strength of finished part
-Improved accuracy and surface finish
-Smaller stress in dies and longer die life than in conventional cold forging
-Reduction of noise and vibrations
-Smaller parts
(Metal shaping processes: casting and molding, particulate processing, deformation processes, and metal removal ,Vukota Boljanovic, pp166,167)
