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  Method and apparatus for grindingUSPTO Application #: 20060040584Title: Method and apparatus for grinding Abstract: Apparatus for high speed grinding includes a diamond-bonded abrasive wheel, a drive mechanism for mounting and rotating the grinding wheel at peripheral speeds up to approximately 200 m/s, and a liquid coolant supply system including a delivery system for directing liquid coolant to the point of grinding contact. (end of abstract) Agent: Workman Nydegger (f/k/a Workman Nydegger & Seeley) - Salt Lake City, UT, US Inventors: Charles Ray, Stephen Ray USPTO Applicaton #: 20060040584 - Class: 451005000 (USPTO) Related Patent Categories: Abrading, Precision Device Or Process - Or With Condition Responsive Control, Computer Controlled The Patent Description & Claims data below is from USPTO Patent Application 20060040584. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] The invention concerns a method and apparatus for grinding. In particular, it relates to an improvement in a process called creep-feed grinding by means of which a very high material removal rate ("MRR") is achieved. [0002] The invention is particularly useful in removing material for particularly difficult to machine materials, for example, titanium alloy. The known processes of removing material are conventionally achieved by milling or broaching. However, each process has particular disadvantages for example, when milling titanium alloys the cycle time is relatively long and the consumable cost per item is increased because the milling cutter itself machines relatively few parts before requiring refurbishment. Therefore, the geometrical quality can sometimes be affected, particularly when dealing with complex forms. [0003] The use of broaching materials such as titanium alloys is more common but there are significant set-up costs and refurbishments costs. Furthermore, the component can be subjected to higher cutting forces during removal of the materials. [0004] It is known to grind tough materials, but only when there is a very small amount of material to be removed. Such a grinding process uses a silicon carbide abrasive wheel type to grind the component at very low removal rates and is, therefore, considered to be suitable only as a finishing process because the cycle times would be prohibitive for any other use. [0005] One of the current major grinding difficulties in present times centres on the coolant nozzle setup, adjustability and design for a range of grinding wheel profiles. This is normally complex and unreliable. [0006] U.S. Pat. No. 5,826,478 (Zerrer) discloses a hand held, powered cutting tool incorporating a single nozzle for supplying liquid to the external surface of the rotating cutting wheel. Being hand held, the disclosed device is not amenable to precision grinding, and coolant water supplied will be at comparatively low flow and pressure. No provision is made either for changing profile of the cutting wheel or for any automated tool change in use. [0007] EP-A-0924 028 (Rolls Royce) is concerned with an apparatus and method for creep-feed grinding wherein a conventional porous abrasive grinding wheel is used in combination with an applied jet of high pressure coolant directed to an exterior surface of the wheel. The high pressure jet is used for simultaneous cooling of the wheel and workpiece and cleaning of the wheel whereby ground material debris is removed from the abrasive surface particles. Depending upon the position of the workpiece the jet nozzle has to be moved. [0008] EP-A-0 903 200 (Unova) disclose grinding apparatus adapted to grind crankshaft crankpins, provided with a single external coolant nozzle with variable pressure but which is unable to clean the grinding wheel surface. No provision is made for automated tool change. [0009] U.S. Pat. No. 5,961,376 (Gottschald) is concerned with increasing the service life of a grinding wheel by applying low and high pressure coolant intermittently during the grinding process. No provision is made for automated tool change. [0010] EP-0581 507 (Ford) discloses a grinding wheel assembly particularly adapted to the grinding of glass material. The assembly relies upon centrifugal force to accelerate flow of coolant and an arrangement of troughs to guide the coolant to the required areas. In use, the wheel assembly tends to clog and hence requires cleaning. An external cleaning jet is not present and no provision is made for automated tool change. [0011] The inventors have gone against conventional thinking by producing a high speed grinding apparatus, which overcomes, or at least mitigates the problems of the prior art. [0012] According to a first aspect of the present invention there is provided apparatus for high speed grinding comprising a diamond bonded abrasive wheel, drive means for mounting and rotating the grinding wheel at peripheral speeds up to about 200 m/s, and a liquid coolant supply system including delivery means for directing liquid coolant to the point of grinding contact. [0013] According to an optional feature of this embodiment the delivery means is a nozzle arranged to direct a jet of liquid coolant at the point of grinding contact in a direction substantially tangental to the wheel. [0014] Alternatively, delivery means is provided through the grinding wheel, which delivery means comprises a plurality of channels for connecting an interior chamber to the exterior surface of the grinding wheel. [0015] In some embodiments, the plurality of channels is provided by radial slots formed in the grinding wheel. Preferably, the liquid coolant is supplied to the chamber. More preferably, the liquid coolant supplied to the internal chamber is directed within the chamber by guide means towards the point of grinding contact. [0016] According to another optional feature of this aspect of the invention, there further comprises a second nozzle to direct a jet of liquid coolant to the periphery of the wheel to clean the wheel surface. [0017] In one class of embodiments, the liquid coolant supply system in use, delivers liquid coolant to the chamber at a pressure of between 0 to 100 Bar. Preferably, the jet of liquid coolant is supplied to the second nozzle at a pressure in excess of 40 Bar. [0018] Optionally, the jet of liquid coolant to clean the wheel is directed at a point spaced from the contact zone. Preferably, the second nozzle means is arranged to direct a jet of liquid coolant away from the grinding contact in a substantially radial direction to the wheel. [0019] It is most preferred to incorporate a zoned control of coolant delivery to the interior of the wheel. [0020] Unlike the externally applied coolant-jet cleaning (which can take place almost anywhere on the wheel periphery) the cooling and lubricating effect of the internal coolant should be controlled and aimed into the contact zone. As the contact zone may change (anywhere within 300.degree. radial arc) it is important to control the point of exit. Also the rotational speed of the wheel affects the coolant point of exits from the slots. [0021] There are preferably four zones that can be used in any combination to ensure the point of contact is always kept flooded with coolant. Depending on wheel rotational speed and point of contact the appropriate zone or zones can be switched on through a machine control to ensure the contact zone is always flooded. [0022] According to a further optional feature of this aspect of the invention, there further comprises a controller to control the rotational speed of the grinding wheel and select a contact zone to supply the liquid coolant. [0023] The grinding wheel may be composed of diamond bonded abrasive wheel in either a resin, galvanic, vitrified or metal bonded construction. [0024] A second aspect of the invention comprises a method of carrying out a grinding operation on a work piece at a high material removal rate including the steps of (i) setting up the grinding wheel for a series of cuts of potentially different depths either "up cut" or "down cut" grinding; (ii) selecting the nozzle zone; (iii) setting up the apparatus to direct liquid coolant at the grinding contact point; and (iv) grinding the work piece by rotating the grinding wheel at peripheral speeds in excess of 10 m/s. There may further comprise the step of moving the table speed in excess of about 2 m per minute. Continue reading... Full patent description for Method and apparatus for grinding Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Method and apparatus for grinding patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Method and apparatus for grinding or other areas of interest. ### Previous Patent Application: Method and apparatus for abrasive circular machining Next Patent Application: Method and apparatus for polishing a semiconductor device Industry Class: Abrading ### FreshPatents.com Support Thank you for viewing the Method and apparatus for grinding patent info. IP-related news and info Results in 1.23603 seconds Other interesting Feshpatents.com categories: Accenture , Agouron Pharmaceuticals , Amgen , AT&T , Bausch & Lomb , Callaway Golf |
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