Abrading – Abrading process – Drill – thread – thread cutter – reamer – or rotary cutter abrading
Reexamination Certificate
2000-12-22
2004-03-30
Rose, Robert A. (Department: 3723)
Abrading
Abrading process
Drill, thread, thread cutter, reamer, or rotary cutter abrading
C451S005000
Reexamination Certificate
active
06712675
ABSTRACT:
This invention refers to a method for grinding at least one surface on a cutting blade used in machining, with a grinding wheel that rotates around an axis and that has a working area consisting of an annular surface to an advantageous use of said method; and to a grinding wheel used to carry out said method.
There are currently two techniques for grinding cutting blades used in machining, namely form grinding and generating grinding. The main difference between these two grinding techniques is that in form grinding the generatrix is produced on the tool in advance (dressing). In this manner a simple process is created in which the grinding tool carries the profile. Only one feed motion is then required to form a surface. Contrary to this, in generating grinding the generatrix is produced by at least two machine motions, which complicates the process. However, generating grinding is more flexible than form grinding, since a variety of profiles can be produced by any combinations of movement. The increased flexibility is highly desirable if small or medium-sized batches of special profiles have to be produced. In this case it is not necessary to dress the generating profile into the grinding wheel. However, generating grinding requires more elaborate control than form grinding.
A method of the above-given type is known from U.S. Pat. No. 5,168,661. In this known method a special grinding wheel configuration and a particular sequence of motions are utilized in moving the cutting blade relative to the grinding wheel, to enable the formation of a plurality of desired surfaces on a cutting blade. Furthermore, spiral-shaped furrows produced on the workpiece surface by the grain protruding highest from the grinding wheel are to be avoided. For this purpose, the known method utilizes a profile grinding wheel which is described and illustrated in the aforementioned U.S. Pat. No. 5,168,661, but which is claimed in U.S. Pat. No. 5,241,794. This known profile grinding wheel has a grinding profile which for finish grinding has a narrow, substantially flat surface on the outer portion of the wheel surface. This flat surface is kept substantially tangent to a workpiece surface during finish grinding. This profile grinding wheel consists of an expensive, highly durable abrasive material such as CBN crystals. However, other materials such as aluminum oxide can also be used, since the profile grinding wheel does not need to be dressed. Aside from the narrow, flat surface used for finish grinding, the working area of the known profile grinding wheel has an inner conical surface, an inner arcuate surface and an outer arcuate surface. The inner conical surface, the inner arcuate surface and/or the outer arcuate surface is/are used for rough grinding. The roughed blade surface is subsequently finished with the narrow flat surface.
This known method requires a complex sequence of movements, since every surface to be ground on the cutting blade is first roughed at least with the inner conical surface and subsequently finished with the narrow flat surface. The profile grinding wheel utilized in the known method comprises materials with different grain sizes in their rough grinding and finish grinding areas. The roughing and finishing work to be performed by the known profile grinding wheel is thus distributed over two different grinding wheel areas, of which the one area is used only for rough grinding and the other only for finish grinding. The cutting blades ground with the known method are common high-speed steel blades. A further disadvantage of the known method is that it is not possible to finish grind concave surfaces, since the finish grinding is always performed with the narrow flat surface. Another disadvantage of the known generating grinding method is that because of the CBN wheels employed in this method, cemented carbide blades can not be ground. A CBN wheel would not be adequately stable for machining cemented carbide blades. However, cemented carbide blades can not easily be form ground either. A broad diamond wheel would be necessary to form grind cemented carbide blades. However, such diamond wheels are very difficult to condition.
For example, to produce the teeth of a gear it can be necessary to use six different types of blades in order to produce six different profiles. These six profiles could be produced on a borazon grinding wheel by reprofiling. This would not be economical on a diamond grinding wheel. Instead, several different diamond wheels would have to be provided for the form grinding.
The object of the invention is to provide a method of the type given above, having a simpler machining cycle and enabling use of a more simply configured grinding wheel, and particularly permitting grinding to be performed on curved surfaces as well. Furthermore, an advantageous use of the method and a grinding wheel for carrying out said method are to be provided.
Contrary to the known method using a grinding wheel with a complex configuration, in the method according to the invention a universal grinding wheel can be used which has a working area consisting of an annular surface, the axial cross section of which has an arcuate profile. With the method according to the invention a surface is first generated on the cutting blade by grinding with the annular surface during a first orientation in space between the grinding wheel and the cutting blade by means of at least one first relative translational movement between the grinding wheel and the cutting blade, and then at least one part of the generated surface is reground with the annular surface during a second orientation in space between the grinding wheel and the cutting blade by means of at least one second relative translational movement between the grinding wheel and the cutting blade. According to the invention, in this manner a surface can be ground with one area of the annular surface, and it can then be reground with another area of the annular surface. The grinding wheel utilized in the method of the invention does not have to have different specifications for this in these two areas. This is because the same surface of the cutting blade can be ground and subsequently reground, that is roughed and finished, for example, solely through selection of the appropriate parameters together with the two different spatial orientations. This is true irrespective of whether the completed surface is planar, convex or concave. The grinding wheel used in the method of the invention needs only one radius in its working area, and it therefore has a substantially more simple configuration than the grinding wheel used in the known method. The process in the method according to the invention is likewise substantially simpler than in the known method, since just two different spatial orientations can be selected, for example by choosing a different angle for the cutting blade in relation to the grinding wheel. Thus, the method according to the invention is far more flexible in use than the known method. The spiral-shaped furrows, which are avoided in the known method by complicated means, are also avoided by the method according to the invention, without the necessity of using a grinding wheel with a narrow flat surface for the finish grinding.
It is possible to generate cemented carbide blades using the present invention. This is a very significant application of the method according to the invention, since dry milling, in which cutting blades of cemented carbide have to be used, is becoming increasingly common in gear production. Cemented carbide can only be machined with diamond, but diamond profile grinding wheels can hardly be profiled by dressing. Therefore, profile grinding of cemented carbide blades is virtually ruled out. Thus, simply by utilization of a diamond grinding wheel, the method according to the invention can be implemented not only for the generating grinding of cutting blades of high-speed steel, but also for that of cemented carbide cutting blades.
According to the invention, the grinding wheel used to carry out the method
Giurgiuman Horia
Knaden Manfred
Ley John R.
Oerlikon Geartec AG
Rose Robert A.
LandOfFree
Method for grinding at least one surface on a cutting knife... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for grinding at least one surface on a cutting knife..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for grinding at least one surface on a cutting knife... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3195598