Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
2002-12-31
2004-12-28
Picard, Leo (Department: 2125)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C700S172000, C700S173000, C409S131000, C409S136000
Reexamination Certificate
active
06836697
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method of determining cutting forces, and also to a calculator which utilizes the new method.
Turning and boring operations become productive when machining conditions such as cutting speed, feed per revolution, and depth of cut are properly selected according to the cutting tool material and geometry, mechanical properties of the workpiece material, and technical characteristics of the machine tool. Besides that, ability to determine cutting forces allows for setting maximum productivity within machine tool power capacity and prevents stalling the machine tool. The cutting forces are: tangential, feed, and radial. Tangential force F
t
is determined by the formula, which is used when turning and boring as disclosed in E. Isakov “Reassessing power factors”, American Machinists, December 1996, pages 43-45.
F
t
=396000
dfp
(lbf)
where d=depth of cut, in., f=feed rate, in/rev.
p=specific power, hp/in.
3
/min, and 396000 is a conversion factor.
Determined tangential force F
t
and selected cutting speed V
c
allow for determination of the required machining power P:
P=F
t
V
c
/33000(hp)
where 33000 is a conversion factor.
Feed F
f
and radial F
r
forces are proportional to tangential force F
t
. It is a common practice to consider that F
f
=0.5 F
f
and F
r
=0.25 F
t
. Unfortunately, this method of feed and radial force determination has acceptable accuracy only when applied to some carbon steels in annealed and normalized conditions.
Another known method as disclosed in E. Isakov “Reassessing power factors”, American Machinists, December 1996, pages 43-45 provides more accurate formulas for determination of feed F
f
and radial F
r
forces at the following cutting conditions.
F
f
=0.581 F
t
−18.3: AISI 1018 and 316 steels, 140-200 HB, 0.008-0.01 ipr feed, 0.06-0.3 in. depth of cut
F
f
=0.458 F
t
−6.6: AISI 1045 and 4140 steels, 140-200 HB, 0.012-0.02 ipr feed, 0.06-0.3 in. depth of cut F
f
=0.556 F
t
−5.3: AISI 4340 and H11 steels, 205-260 HB, 0.008-0.012 ipr feed, 0.06-0.3 in. depth of cut F
f
=0.477 F
t
+7.3: AISI 4140 and 410 steels, 205-260 HB, 0.015-0.02 ipr feed, 0.06-0.3 in. depth of cut
F
r
=0.145 F
t
+32.0: AISI 1018 and 316 steels, 140-200 HB, 0.01-0.02 ipr feed, 0.06-0.15 in. depth of cut
F
r
=0.182 F
t
−9.3: AISI 1045 and 4140 steels, 140-200 HB, 0.01-0.02 ipr feed, 0.18-0.3 in. depth of cut
F
r
=0.111 F
t
+40.7: AISI 4340 and H11 steels, 205-260 HB, 0.008-0.012 ipr feed, 0.06-0.3 in. depth of cut
F
r
=0.143 F
t
+48.7: AISI 4140 and 410 steels, 205-260 HB, 0.015-0.02 ipr feed, 0.06-0.3 in. depth of cut.
These formulas are utilized in the electronic “Metalcutting Force and Power Calculator: Turning and Boring” E. Isakov “Metalcutting Force and Power Calculator” (Turning, Boring, Milling)” on the 3.5 inch diskette.kennametal, Inc. 1998.
Limitations of these formulas are as follows:
Applied only to a few grades of carbon (1018 and 1045), alloy (4140 and 4340), stainless (316 and 410), and tool (H11) steels having Brinell hardness numbers from 140 to 260 HB.
If hardness of the above-mentioned work materials is indicated in other then Brinell hardness numbers, the equivalent hardness numbers should be found in the appropriate handbooks.
Applied to the feed rates from 0.008 in./rev. to 0.020 in./rev.
Applied to the depth of cuts from 0.060 in. to 0.300 in.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a method of determining cutting forces, and a calculator which uses the method, which avoids the disadvantages of the prior art.
In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides in a method of determining cutting forces in accordance with which the work materials are divided into special new groups which differ from one another by Brinell hardness, and feed and radial forces are determined from a tangential force differently for the material of each group and also differently for a turning process and for a boring process.
In accordance with another feature of the present invention a calculator is provided in which the determination of feed and radial forces is performed in accordance with the above specified inventive method.
The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments.
REFERENCES:
patent: 4584649 (1986-04-01), Komanduri et al.
Kasenge Charles
Picard Leo
Zborovsky I.
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