CA1112492A - Method of machining end faces - Google Patents
Method of machining end facesInfo
- Publication number
- CA1112492A CA1112492A CA305,923A CA305923A CA1112492A CA 1112492 A CA1112492 A CA 1112492A CA 305923 A CA305923 A CA 305923A CA 1112492 A CA1112492 A CA 1112492A
- Authority
- CA
- Canada
- Prior art keywords
- tool
- machining
- cutting
- workpiece
- angle
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000003754 machining Methods 0.000 title claims abstract description 46
- 238000000034 method Methods 0.000 title claims abstract description 28
- 230000033001 locomotion Effects 0.000 claims abstract description 31
- 238000005520 cutting process Methods 0.000 description 49
- 239000000463 material Substances 0.000 description 10
- 230000006872 improvement Effects 0.000 description 6
- 239000013598 vector Substances 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 230000036039 immunity Effects 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 2
- 230000000295 complement effect Effects 0.000 description 2
- 230000001771 impaired effect Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000011089 mechanical engineering Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- RZVAJINKPMORJF-UHFFFAOYSA-N Acetaminophen Chemical compound CC(=O)NC1=CC=C(O)C=C1 RZVAJINKPMORJF-UHFFFAOYSA-N 0.000 description 1
- 229910001018 Cast iron Inorganic materials 0.000 description 1
- 208000036366 Sensation of pressure Diseases 0.000 description 1
- 229910000746 Structural steel Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 229940000425 combination drug Drugs 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 239000002826 coolant Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000004513 sizing Methods 0.000 description 1
- 238000007514 turning Methods 0.000 description 1
Landscapes
- Turning (AREA)
- Milling Processes (AREA)
Abstract
METHOD OF MACHINING END FACES
Abstract of the Disclosure The invention relates to methods of machining end faces with rotary tools. The method according to the invention comprises imparting to the workpiece a rotary motion and to the tool - a straight feed motion at an angel 20 - 75° to the radius of the workpiece.
Abstract of the Disclosure The invention relates to methods of machining end faces with rotary tools. The method according to the invention comprises imparting to the workpiece a rotary motion and to the tool - a straight feed motion at an angel 20 - 75° to the radius of the workpiece.
Description
Z4~Z
The invention relates to methods of machining end faces with rotary tools.
The invention may be most advantageously used in the mechanical engineering, aircraft, shipbuilding and other in-dustries for sizing and finishing machining of end faces pre-ferably of ring-shaped workpieces manufactured of ductile hard-to-machine materials having a tendency to intense excre-scence formation during cutting which materially reduces quality and accuracy of machining.
Metal cutting is a leading technique in the mechanical engineering which is due to its wide capabilities of ensuring minimum possible cycle of preparation to the production of structurally intricate workpieces, low power requirements and big savings in performing complicate and labour-consuming fi-nishing operations. The main problem of the development of the cutting technique is associated with an improvement of its productivity with concurrent meetint of high requirements imposed on accuracy and quality of machining of surfaces. The importance of the problem become greater due to a widespread application in the technology of new hard-to-machine materials making the machining performance 1~ - 25 times lower than in cutting carbon and alloyed structural steel.
~k
The invention relates to methods of machining end faces with rotary tools.
The invention may be most advantageously used in the mechanical engineering, aircraft, shipbuilding and other in-dustries for sizing and finishing machining of end faces pre-ferably of ring-shaped workpieces manufactured of ductile hard-to-machine materials having a tendency to intense excre-scence formation during cutting which materially reduces quality and accuracy of machining.
Metal cutting is a leading technique in the mechanical engineering which is due to its wide capabilities of ensuring minimum possible cycle of preparation to the production of structurally intricate workpieces, low power requirements and big savings in performing complicate and labour-consuming fi-nishing operations. The main problem of the development of the cutting technique is associated with an improvement of its productivity with concurrent meetint of high requirements imposed on accuracy and quality of machining of surfaces. The importance of the problem become greater due to a widespread application in the technology of new hard-to-machine materials making the machining performance 1~ - 25 times lower than in cutting carbon and alloyed structural steel.
~k
-2- -~
~124~2 Known methods aimed at improving the performance of cutting, accuracy and quality of finished surfaces which are based on improvement of construction and optimization of geome-trical parameters of cutting portion of known tools, improve-ment of quality of their working surfaces, application of newtypes of coolants and special machining methods, such as super-high speed cutting with heating or deep cooling of a tool or a workpiece are either rather complicated and labour-consuming or insufficiently effective.
At the same time, an important reserve for an expan-sion of production capabilities of cutting rests with methods of rotary cutting in which additional rotation is imparted to circular cutting edges of a tool about its axis. This is en-sured by appropriately positioning the tool relative surface to be machined.
With the rotary cutting, due to an additional rotation of the cutting edges of the tool, the sliding speed of the working surfaces of the tool relative to the material being machined is lowered by 1.5 - 3 times in comparison with the known methods. Furthermore, the length of the active portion of the cutting edge is increased and the time of contact of each point of the cutting blade with the material being ma-chined is reduced by scores of times, respectively. The com-bination of the above advantages ensures a multiple increase in the tool life, hence improves productivity, accuracy and quality of machining.
4~2 Alongside the above advantages of the rotary cutting, this method exhibits a disadvantage of low immunity to vibra-tions. This limits the possibilities of the method as regards the provision of high accuracy and quality of machining.
Known in the art is a method for rotary cutting dis-closed in USSR Inventor's Certificate No. 428864 of February 6, 1973, wherein the axis of rotary circular edges of a tool is at 15 - 35 to the base plane. Due to a reduction of the length of contact of the cutting edge with the workpiece being machined, cutting forces decrease, the speed of tool rotation stabilizes thus enabling the reduction of likelihood of appearance of vi-brations during cutting and associated lower quality and accur-acy of machining.
Another way of improving the immunity of the cutting method to vibrations is associated with pre-loading of the tool by forces compensating for the effect of cutting forces on de-formation of elements of the tool. Known in the art is a method for rotary cutting disclosed in USSR Inventor's Certificate No.
536886 of February 11, 1975, wherein the rotary portion of a rotary tool is pre-loaded by forces close in magnitude and opposite in direction to the cutting forces. The method enables an improvement of immunity of the cutting process to vibrations, hence accuracy and quality of machining.
Xnown in the art is a method of machining end faces with rotary tools, wherein a rotary motion is imparted to a work-piece and a straight feed motion is imparted to the tool radially of the workpiece.
The use of conventional rotary cutting methods for machining end faces is insufficiently effective as regards high quality and accuracy of the machining as the process is effected at varying actual cutting speed. This is inevitably reflected on the nature of phenomena occuring in zones of contact of the working surfaces of the tool and material being machined. As a result, the cutting process is accompa-nied by a continuous fluctuation of friction forces and coef-ficient of friction, chip shrinkage, relative shear, cutting forces and temperature, intensity of wear of the cutting edge, size and shape of excrescence formed thereon and the like. This results, during the machining, in variation of quality and accuracy parameters (shape and height of micro-irregularities, degree and depth of surface plastic deforma-tion, value and nature of distribution of residual stresses, the size of bearing surface, reflective power and the like).
Therefore, certain portions of the machined surface have dif-ferent quality of machining, differ in accuracy, geometricalshape and dimensions, hence in operating performance.
It is a general object of the invention to provide a method of machining end faces with rotary tools which enables an improvement of quality of machining.
~Z4~Z
Another object of the invention is to provide a method of machining end faces with rotary tools which enables high quality of machining~
Still another object of the invention is to provide a method of machining end faces which enables sta~ilization of actual cutting speed during the entire machining cycle.
In accordance with these and other objects, the inven-tion consists in that a method of machining end faces with rotary tools comprises imparting a rotary motion to a work--piece and imparting a straight feed motion to the tool radial-ly of the workpiece, which feed motion, according to the in-vention is effected at 20 - 75 to the workpiece radius.
Due to the face that the tool is fed at 20 - 75 to the workpiece radius, actual cutting speed is stabilized during the entire machining cycle, which contributes to an improve-ment of qua?ity and accuracy of machined surfaces.
The selection of an angle of the feed motion within the above-specified limits is explained by the following considera-tions. As a result of the displacement of the tool at an angle to the radius of the workpiece it takes place continuous variation of positioning of its cutting edge relative to the direction of the vector of rotary speed of the workpiece at an apex of the tool. The angle of positioning of the tool relative to the akove-mentioned vector which is a complemen-tary angle to 90 for the motion angle also changes. Minimum ~$1;24~2 value of the positioning angle is limited by the stabilityof the tool rotation during machining and is 15. Therefore, the feed motion angle is 90 - 15 = 75.
With positioning angles of the tool exceeding 70~ in-complete separation of chip from the base material occurs.This is accompanied by a material increase in forces applied to the tool, and vibrations appear which result in an intense chipping of the cutting edge and impaired accuracy and quali-ty of machining. Thus, the lower limit of the feed motion -angle is 90 - 70 = 20.
These and other objects and advantages of the inven-tion will become apparent from the following detailed descrip-tion of an embodiment thereof with reference to the accompany-ing drawings, in which:
Figure 1 diagrammatically shows the relative position of a rotary tool and a ring-shaped workpiece;
Figure 2 is a sectional view taken along the line II-II in Figure 1.
According to the invention, it is contemplated a method of machining end faces with rotary tools in which a rotary motion is imparted at a speed nl to a workpiece 1 being machined (Figure 1) about its geometrical axis l this motion being the main motion. A tool 2 is mounted relative to a machined surface 3 (Figure 2) of the workpiece 1 in such a man-Z
ner that the plane of its cutting edge 4 is at an angle ~ tothe machined surface 3. The value of the angle is varied within 5 - 45 depending on ratios of workpiece dimensions and requirements to roughness of machined surface. Rotation of the tool 2 about its axis 2 is effected due to its engage-ment with the workpiece 1 (n2 is rotary speed of the tool).
To ensure stability of this rotary motion, the plane of incli-nation of the axis 2 of the tool 2 is turned at points A
and B (Figure 1) relative to vectors VAl and V2B of the main -motion at angles ~A and ~B~ respectively.
It is known that actual cutting speed V is equal tothe sliding speed of the clearance face of the tool 2 relative to the machined w~rkpiece 1, and in cutting with a rotary tool, this speed is V = Vl , (1) wherein Vl is rotary speed of the workpiece, ~1 is speed factor.
With steady rotation of the tool and with low ratios t/d (t is cutting depth, d is diameter of the cutting portion), the tool automatically gains the performance with minimum friction speeds at the clearance face, and in such case the formula = COS~ (2) is true with an error less than 5% and wherein ~ is an angle between the plane of inclination of axis 2 of the tool 2 ~i~2~2 relative to the vector of the main motion of the tool at an apex 03 (Fig. 2) of the tool (more exactly of its cutting edge corresponding to the maximum introduction into the ma-terial to be treated.
~t has been found that, to provide for constant actual cutting speeds at all points of the path of relative motion of the tool 2 and machined surface 3, the tool 2 should be caused to move during the machining along a straight line AB
which is at an angle ~ to the radius A01 of the workpiece 1;
this angle being referred to below as the feed motion angle.
Since the vectors ~ and V2B of the speed of the main motion at the end points A and B of the path of the straight-line motion of the tool 2 differ not only in value, but also in direction, the actual value of the positioning angle changes during the machining (~A~B)' Let us draw a diameter in parallel with the line AB
through the axis l of rotation of the workpiece 1. Perpendi-culars AD and BE are drawn through the points A and B which are located at a distance equal to radiuses RA and RB from the rotational axis of the workpiece 1, to the line AB, ~he perpendiculars being equal to each other (AD = BE - H).
From the triangles ADOl and BEOl it is found that H = RA cos~A = RB CS~B
The ratio of actual cutting speeds at the points A
and B
_ = _ A , (4) vB 1 B
~24~2 wherein VA and VB are actual cutting speeds at the points and B, and Vl are linear speeds of the workpiece at the points A and B, A and B are speed factors at the points A and B, or using the formula (2):
cos~ R cos~
= _1 A = A A (5) vB VlB cos~B RB cos~B
Compare (3) and (5) to find that VA = VB, that is the actual cutting speed for the rotary tool 2 during its move-ment at an angle ~ to the radius RA of the workpiece 1 re-mains unchanged.
The feed motion may be effected along a straight line either between the points A and B (from the greater radius RA to the smaller radius RB) or in the opposite direction, between the points B and A, which can only change the pattern of machining and direction of chip separation.
Minimum value of the positioning angle ~ is limited by the stability of rotation of the tool 2 during machining and is 15.
With angles ~ exceeding 70 incomplete separation of chip from the base material occurs. Thus forces applied to the tool increase, and appear vibrations to result in an in-tense chipping of the cutting edge and in impaired accuracy and quality of machining.
. , .
~1;24~2 Since the angle ~ of the feed motion is a complementary angle to 90 for the positioning angle ~, and taking into account the limitations for the angle ~, the range of varia-tion of the angle ~ between the feed direction and the radial direction is found to be from 20 to 75.
With pre-set radiuses of machining RA and ~, such value of the angle ~ is selected which does not deviate beyond the limits of the above-mentioned range. In practice, the machining with the feed motion at the angle ~ to the radial-direction is effected by shifting the point A of the tool rela-tive to the axis l of rotation of the workp~ece by an amount H
which should be within the following ranges:
RA cos~A ~ H ~ RB cos~B
The following examples illustrate the manner in which the method is carried out.
Example 1 The end face of a ring-shaped workpiece having outside and inside dimensions of RA = 200 mm and RB = 75 mm, respect-ively, and height of 43 mm was machined. The material of the workpiece - low-carbon steel containing 0.2% of carbon. The machining was effected on a lathe. Machining conditions:
spindle speed 250 rpm, cutting depth 0.2 - 0.3 mm, feed 0.7 mm/rev.
The machining was effected by means of a rotary tool in the direction from the smaller radius to the greater radius.
~Z4G,,~Z
The shift H of the tool point relative to the rotational axis of the workpiece with minimum value of the positioning angle ~ was determined:
HB = RB cos~B = 75 cos 15 = 72.75 mm.
For the end point A, with maximum value of the angle A
HA = RA cos~A = 200 cos 70 = 68.4 mm.
Since the values of HA and HB differed only slightly, the mean value of the shift H = 70.5 mm was chosen. Then the 0 angle ~ between the feed motion and the workpiece radius was ~ = arc sin (cos~B) = arc sin H = 7010'.
B
After positioning the tool with the shift at the value of H relative to the center axis of the lathe, the operator put on the spindle rotation and the feed motion. The machin- -ing cycle was completed in 0.8 minutes. The height of micro-irregularites was 3 - 5 mcm, maximum deviation from planeness was 0.03 mm.
Example 2 A working end face of a workpiece of the type of pres-sure disc for a friction clutch was machined on a vertical two-spindle semi-automatic lathe; the material was modified cast iron. Workpiece dimensions: RA = 132 mm, RB = 56 mm. The mach-ining was effected beginning from the side of the greater radius.
~;Z4~2 The value of shift for the two end points A and B was determined:
~A = 45.1 mm, HB = 54.3 mm-'~he mean value ~ = 50 i~m was selected.
Then the angle J\ o~ feed motion was = arc sin ~ = 2220'.
~~ achining conditions: cutting depth - 0.3 mm, ~eed 0.8 mm/rev, workpiece speed - 600 rpm.
After the tool was positloned with a shift H, the opera-tor clamped the workpiece in ~he lathe and put it on. T~e machining cycle was completed in 0.15 minu~es. The tool li~e was 300 minutes of machinin~ time. Height of microirregulari-ties of the surface was 5 - 7 mcm, maximum deviation from planeness was 0.05 mm.
~ ample 3 A split plane o~ a welded gear case of low-carbon steel containing about 0.3~ of carbon was machined on a vertical turret lathe. The ~Jorkpiece was clamped on the rotary table of the lathe so that maximum machining diameter ~as 1900 mm and minimum diameter was 15~0 ~m. 'rhe value of shi,t l~ was determined:
HA = 1900 cos 70 = 1900.3.342 = 650 ~m.
HB = 1580 cos 15 = 1580-0.97 = 1532 ~
~124~2 ~ ince the machining was effected in this case with the feed motion between the ~reater radius and the smaller ra-dius, and due to tne fact that -tne cutting process was of an interrupted, impact nature, minimum possible anglesG~ of turning of the cutting ed~e at the portions of the machi~ed surface having the ~reater radius should be set up.
'~hus H = HB= 15~2 mm wax chosen.
~ hen the angle ~ of the feed motion was = arc sin 1532 = 59040, Machining conditions: cutting depth - 0.15 - 0.20 mm, feed - 1 mm/rev., table speed - 80 rpm.
Height of microirregularities of the machined surfaces was 3 - 8 mcm, maximum deviation from planeness was 0.04 mm over the entire len~th of the case.
While the preferred embodiment of the invention was de-scribed above, it will be understood tha-t various modi~ica-tions may be introduced in the drawing and the method descri-bed wi-thout deviating beyond -the spirit and scope of the invention as defined by the attached claims.
~124~2 Known methods aimed at improving the performance of cutting, accuracy and quality of finished surfaces which are based on improvement of construction and optimization of geome-trical parameters of cutting portion of known tools, improve-ment of quality of their working surfaces, application of newtypes of coolants and special machining methods, such as super-high speed cutting with heating or deep cooling of a tool or a workpiece are either rather complicated and labour-consuming or insufficiently effective.
At the same time, an important reserve for an expan-sion of production capabilities of cutting rests with methods of rotary cutting in which additional rotation is imparted to circular cutting edges of a tool about its axis. This is en-sured by appropriately positioning the tool relative surface to be machined.
With the rotary cutting, due to an additional rotation of the cutting edges of the tool, the sliding speed of the working surfaces of the tool relative to the material being machined is lowered by 1.5 - 3 times in comparison with the known methods. Furthermore, the length of the active portion of the cutting edge is increased and the time of contact of each point of the cutting blade with the material being ma-chined is reduced by scores of times, respectively. The com-bination of the above advantages ensures a multiple increase in the tool life, hence improves productivity, accuracy and quality of machining.
4~2 Alongside the above advantages of the rotary cutting, this method exhibits a disadvantage of low immunity to vibra-tions. This limits the possibilities of the method as regards the provision of high accuracy and quality of machining.
Known in the art is a method for rotary cutting dis-closed in USSR Inventor's Certificate No. 428864 of February 6, 1973, wherein the axis of rotary circular edges of a tool is at 15 - 35 to the base plane. Due to a reduction of the length of contact of the cutting edge with the workpiece being machined, cutting forces decrease, the speed of tool rotation stabilizes thus enabling the reduction of likelihood of appearance of vi-brations during cutting and associated lower quality and accur-acy of machining.
Another way of improving the immunity of the cutting method to vibrations is associated with pre-loading of the tool by forces compensating for the effect of cutting forces on de-formation of elements of the tool. Known in the art is a method for rotary cutting disclosed in USSR Inventor's Certificate No.
536886 of February 11, 1975, wherein the rotary portion of a rotary tool is pre-loaded by forces close in magnitude and opposite in direction to the cutting forces. The method enables an improvement of immunity of the cutting process to vibrations, hence accuracy and quality of machining.
Xnown in the art is a method of machining end faces with rotary tools, wherein a rotary motion is imparted to a work-piece and a straight feed motion is imparted to the tool radially of the workpiece.
The use of conventional rotary cutting methods for machining end faces is insufficiently effective as regards high quality and accuracy of the machining as the process is effected at varying actual cutting speed. This is inevitably reflected on the nature of phenomena occuring in zones of contact of the working surfaces of the tool and material being machined. As a result, the cutting process is accompa-nied by a continuous fluctuation of friction forces and coef-ficient of friction, chip shrinkage, relative shear, cutting forces and temperature, intensity of wear of the cutting edge, size and shape of excrescence formed thereon and the like. This results, during the machining, in variation of quality and accuracy parameters (shape and height of micro-irregularities, degree and depth of surface plastic deforma-tion, value and nature of distribution of residual stresses, the size of bearing surface, reflective power and the like).
Therefore, certain portions of the machined surface have dif-ferent quality of machining, differ in accuracy, geometricalshape and dimensions, hence in operating performance.
It is a general object of the invention to provide a method of machining end faces with rotary tools which enables an improvement of quality of machining.
~Z4~Z
Another object of the invention is to provide a method of machining end faces with rotary tools which enables high quality of machining~
Still another object of the invention is to provide a method of machining end faces which enables sta~ilization of actual cutting speed during the entire machining cycle.
In accordance with these and other objects, the inven-tion consists in that a method of machining end faces with rotary tools comprises imparting a rotary motion to a work--piece and imparting a straight feed motion to the tool radial-ly of the workpiece, which feed motion, according to the in-vention is effected at 20 - 75 to the workpiece radius.
Due to the face that the tool is fed at 20 - 75 to the workpiece radius, actual cutting speed is stabilized during the entire machining cycle, which contributes to an improve-ment of qua?ity and accuracy of machined surfaces.
The selection of an angle of the feed motion within the above-specified limits is explained by the following considera-tions. As a result of the displacement of the tool at an angle to the radius of the workpiece it takes place continuous variation of positioning of its cutting edge relative to the direction of the vector of rotary speed of the workpiece at an apex of the tool. The angle of positioning of the tool relative to the akove-mentioned vector which is a complemen-tary angle to 90 for the motion angle also changes. Minimum ~$1;24~2 value of the positioning angle is limited by the stabilityof the tool rotation during machining and is 15. Therefore, the feed motion angle is 90 - 15 = 75.
With positioning angles of the tool exceeding 70~ in-complete separation of chip from the base material occurs.This is accompanied by a material increase in forces applied to the tool, and vibrations appear which result in an intense chipping of the cutting edge and impaired accuracy and quali-ty of machining. Thus, the lower limit of the feed motion -angle is 90 - 70 = 20.
These and other objects and advantages of the inven-tion will become apparent from the following detailed descrip-tion of an embodiment thereof with reference to the accompany-ing drawings, in which:
Figure 1 diagrammatically shows the relative position of a rotary tool and a ring-shaped workpiece;
Figure 2 is a sectional view taken along the line II-II in Figure 1.
According to the invention, it is contemplated a method of machining end faces with rotary tools in which a rotary motion is imparted at a speed nl to a workpiece 1 being machined (Figure 1) about its geometrical axis l this motion being the main motion. A tool 2 is mounted relative to a machined surface 3 (Figure 2) of the workpiece 1 in such a man-Z
ner that the plane of its cutting edge 4 is at an angle ~ tothe machined surface 3. The value of the angle is varied within 5 - 45 depending on ratios of workpiece dimensions and requirements to roughness of machined surface. Rotation of the tool 2 about its axis 2 is effected due to its engage-ment with the workpiece 1 (n2 is rotary speed of the tool).
To ensure stability of this rotary motion, the plane of incli-nation of the axis 2 of the tool 2 is turned at points A
and B (Figure 1) relative to vectors VAl and V2B of the main -motion at angles ~A and ~B~ respectively.
It is known that actual cutting speed V is equal tothe sliding speed of the clearance face of the tool 2 relative to the machined w~rkpiece 1, and in cutting with a rotary tool, this speed is V = Vl , (1) wherein Vl is rotary speed of the workpiece, ~1 is speed factor.
With steady rotation of the tool and with low ratios t/d (t is cutting depth, d is diameter of the cutting portion), the tool automatically gains the performance with minimum friction speeds at the clearance face, and in such case the formula = COS~ (2) is true with an error less than 5% and wherein ~ is an angle between the plane of inclination of axis 2 of the tool 2 ~i~2~2 relative to the vector of the main motion of the tool at an apex 03 (Fig. 2) of the tool (more exactly of its cutting edge corresponding to the maximum introduction into the ma-terial to be treated.
~t has been found that, to provide for constant actual cutting speeds at all points of the path of relative motion of the tool 2 and machined surface 3, the tool 2 should be caused to move during the machining along a straight line AB
which is at an angle ~ to the radius A01 of the workpiece 1;
this angle being referred to below as the feed motion angle.
Since the vectors ~ and V2B of the speed of the main motion at the end points A and B of the path of the straight-line motion of the tool 2 differ not only in value, but also in direction, the actual value of the positioning angle changes during the machining (~A~B)' Let us draw a diameter in parallel with the line AB
through the axis l of rotation of the workpiece 1. Perpendi-culars AD and BE are drawn through the points A and B which are located at a distance equal to radiuses RA and RB from the rotational axis of the workpiece 1, to the line AB, ~he perpendiculars being equal to each other (AD = BE - H).
From the triangles ADOl and BEOl it is found that H = RA cos~A = RB CS~B
The ratio of actual cutting speeds at the points A
and B
_ = _ A , (4) vB 1 B
~24~2 wherein VA and VB are actual cutting speeds at the points and B, and Vl are linear speeds of the workpiece at the points A and B, A and B are speed factors at the points A and B, or using the formula (2):
cos~ R cos~
= _1 A = A A (5) vB VlB cos~B RB cos~B
Compare (3) and (5) to find that VA = VB, that is the actual cutting speed for the rotary tool 2 during its move-ment at an angle ~ to the radius RA of the workpiece 1 re-mains unchanged.
The feed motion may be effected along a straight line either between the points A and B (from the greater radius RA to the smaller radius RB) or in the opposite direction, between the points B and A, which can only change the pattern of machining and direction of chip separation.
Minimum value of the positioning angle ~ is limited by the stability of rotation of the tool 2 during machining and is 15.
With angles ~ exceeding 70 incomplete separation of chip from the base material occurs. Thus forces applied to the tool increase, and appear vibrations to result in an in-tense chipping of the cutting edge and in impaired accuracy and quality of machining.
. , .
~1;24~2 Since the angle ~ of the feed motion is a complementary angle to 90 for the positioning angle ~, and taking into account the limitations for the angle ~, the range of varia-tion of the angle ~ between the feed direction and the radial direction is found to be from 20 to 75.
With pre-set radiuses of machining RA and ~, such value of the angle ~ is selected which does not deviate beyond the limits of the above-mentioned range. In practice, the machining with the feed motion at the angle ~ to the radial-direction is effected by shifting the point A of the tool rela-tive to the axis l of rotation of the workp~ece by an amount H
which should be within the following ranges:
RA cos~A ~ H ~ RB cos~B
The following examples illustrate the manner in which the method is carried out.
Example 1 The end face of a ring-shaped workpiece having outside and inside dimensions of RA = 200 mm and RB = 75 mm, respect-ively, and height of 43 mm was machined. The material of the workpiece - low-carbon steel containing 0.2% of carbon. The machining was effected on a lathe. Machining conditions:
spindle speed 250 rpm, cutting depth 0.2 - 0.3 mm, feed 0.7 mm/rev.
The machining was effected by means of a rotary tool in the direction from the smaller radius to the greater radius.
~Z4G,,~Z
The shift H of the tool point relative to the rotational axis of the workpiece with minimum value of the positioning angle ~ was determined:
HB = RB cos~B = 75 cos 15 = 72.75 mm.
For the end point A, with maximum value of the angle A
HA = RA cos~A = 200 cos 70 = 68.4 mm.
Since the values of HA and HB differed only slightly, the mean value of the shift H = 70.5 mm was chosen. Then the 0 angle ~ between the feed motion and the workpiece radius was ~ = arc sin (cos~B) = arc sin H = 7010'.
B
After positioning the tool with the shift at the value of H relative to the center axis of the lathe, the operator put on the spindle rotation and the feed motion. The machin- -ing cycle was completed in 0.8 minutes. The height of micro-irregularites was 3 - 5 mcm, maximum deviation from planeness was 0.03 mm.
Example 2 A working end face of a workpiece of the type of pres-sure disc for a friction clutch was machined on a vertical two-spindle semi-automatic lathe; the material was modified cast iron. Workpiece dimensions: RA = 132 mm, RB = 56 mm. The mach-ining was effected beginning from the side of the greater radius.
~;Z4~2 The value of shift for the two end points A and B was determined:
~A = 45.1 mm, HB = 54.3 mm-'~he mean value ~ = 50 i~m was selected.
Then the angle J\ o~ feed motion was = arc sin ~ = 2220'.
~~ achining conditions: cutting depth - 0.3 mm, ~eed 0.8 mm/rev, workpiece speed - 600 rpm.
After the tool was positloned with a shift H, the opera-tor clamped the workpiece in ~he lathe and put it on. T~e machining cycle was completed in 0.15 minu~es. The tool li~e was 300 minutes of machinin~ time. Height of microirregulari-ties of the surface was 5 - 7 mcm, maximum deviation from planeness was 0.05 mm.
~ ample 3 A split plane o~ a welded gear case of low-carbon steel containing about 0.3~ of carbon was machined on a vertical turret lathe. The ~Jorkpiece was clamped on the rotary table of the lathe so that maximum machining diameter ~as 1900 mm and minimum diameter was 15~0 ~m. 'rhe value of shi,t l~ was determined:
HA = 1900 cos 70 = 1900.3.342 = 650 ~m.
HB = 1580 cos 15 = 1580-0.97 = 1532 ~
~124~2 ~ ince the machining was effected in this case with the feed motion between the ~reater radius and the smaller ra-dius, and due to tne fact that -tne cutting process was of an interrupted, impact nature, minimum possible anglesG~ of turning of the cutting ed~e at the portions of the machi~ed surface having the ~reater radius should be set up.
'~hus H = HB= 15~2 mm wax chosen.
~ hen the angle ~ of the feed motion was = arc sin 1532 = 59040, Machining conditions: cutting depth - 0.15 - 0.20 mm, feed - 1 mm/rev., table speed - 80 rpm.
Height of microirregularities of the machined surfaces was 3 - 8 mcm, maximum deviation from planeness was 0.04 mm over the entire len~th of the case.
While the preferred embodiment of the invention was de-scribed above, it will be understood tha-t various modi~ica-tions may be introduced in the drawing and the method descri-bed wi-thout deviating beyond -the spirit and scope of the invention as defined by the attached claims.
Claims
1. A method of machining end faces with rotary tools comprising the steps of:
imparting to the workpiece a rotary motion, imparting to the tool a straight motion at an angle 20 - 75° to the radius of the workpiece.
imparting to the workpiece a rotary motion, imparting to the tool a straight motion at an angle 20 - 75° to the radius of the workpiece.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA305,923A CA1112492A (en) | 1978-06-21 | 1978-06-21 | Method of machining end faces |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA305,923A CA1112492A (en) | 1978-06-21 | 1978-06-21 | Method of machining end faces |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1112492A true CA1112492A (en) | 1981-11-17 |
Family
ID=4111737
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA305,923A Expired CA1112492A (en) | 1978-06-21 | 1978-06-21 | Method of machining end faces |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1112492A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113778039A (en) * | 2021-11-11 | 2021-12-10 | 中国航发沈阳黎明航空发动机有限责任公司 | Characteristic-based blisk machining parameter optimization and quality control method |
-
1978
- 1978-06-21 CA CA305,923A patent/CA1112492A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113778039A (en) * | 2021-11-11 | 2021-12-10 | 中国航发沈阳黎明航空发动机有限责任公司 | Characteristic-based blisk machining parameter optimization and quality control method |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US7216571B2 (en) | Process for twist-free steel cutting of rotational symmetrical surfaces | |
| US4177699A (en) | Method of machining end faces | |
| JP3984052B2 (en) | Cutting method without twisting of rotationally symmetric surfaces | |
| US20080008550A1 (en) | Method for Machining Shaft Bearing Seats | |
| US5122040A (en) | Scroll member and method of forming a scroll member | |
| US6050757A (en) | Rotary milling process and device | |
| CA1112492A (en) | Method of machining end faces | |
| CN102642043B (en) | Method for efficiently cutting optional chamfers of orifices by means of macroprogram | |
| US3841200A (en) | Production of bodies of revolution | |
| US5630684A (en) | Method for machining a scroll member | |
| GB2023479A (en) | Method of machining end faces | |
| RU2185936C2 (en) | Acceleration head | |
| CN113523377A (en) | Cycloid machining method for large-allowance casting blank | |
| JP2000505359A (en) | How to send a tool | |
| SU1708522A1 (en) | Method of abrading irregular surfaces | |
| AT358896B (en) | METHOD FOR MACHINING THE FRONT SURFACES OF RING-SHAPED WORKPIECES | |
| CN212823862U (en) | Novel multifunctional machining cutter | |
| CN212043669U (en) | Machine tool machined part fixing device | |
| NO144326B (en) | PROCEDURE FOR MACHINING ANIMATED FINAL SURFACES | |
| CN211162091U (en) | PCD annular cutter | |
| CA1101243A (en) | Method of machining holes with a spherical tool | |
| RU1815010C (en) | Method of machining spheric surfaces of complex-shaped openings | |
| CN214769024U (en) | Multifunctional turning tool | |
| Chang et al. | Selection of cutting regime for self-propelled rotary cutting tools | |
| SU1355355A1 (en) | Method of machining surfaces of rotation |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |