Note: Descriptions are shown in the official language in which they were submitted.
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A PAIR OF MECHANICAL ELEMENTS COUPLED BY A CO~PLING MECHANISM
This invention relates to the combination of a pair of
mechanical elements and a coupling mechanism for coupling the
elements together, and to machinery incorporating such a com-
bination.
5The present invention includes a coupling mechanism cap-
able of providing a micro-displacement between the coupled
elements that corrects or controls positional error generated
due to thermal deformation or abrasion between the coupled
elements. The type of elements which may he coupled in
accordance with the present invention are for example a coup-
ling portion of the base and the column of the drilling mach-
ine or a coupling portion of the tool post or the tail stock
and their slides, whereby the positional error due to thermal
deformation or abrasion of the machinery is corrected without
spoiling the rigidity in the coupling portions. Additionally
the operational accuracy of the machinery can be maintained,
and also, a controlled micro-displacement can be applied bet-
ween the machine elements according to requirements to enabl~
the machinery to be more versatile in use.
20Heretofore, in a compound lathe, the tool post has been
either fixed to the tool post slide or rotatably mounted
thereto for rotation around a vertical axis (see Figure l),
whilst transverse motion in a direction at right angles to the
- spindle and the tool shaft was not allowed. In Figure l, the
verticial direction of the drawing, hereinafter referred to as
"Y axis direction". Accordingly, for example, when machining
a key way, a milling cutter is normally mounted on the tool
mounting shaft, and the width of the key way to be machined is
controlled by the outside diameter of the milling cutter. When
the cutter is worn, the width of the key way becomes narrow.
Also, if it is desired to increase the width of the key way it
is normally necessary to exchange the cutter for a larger one.
An object of this invention is to retain the operation
accuracy of the machinery by the correction of positional
error due to thermal deformation or abrasion of the machinery
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without spoiling the rigidity in the coupling portions where
the machine elements are mutually coupled. Additionally, it
is an object to provide controlled micro-displacement between
coupled machine elements according to requirements.
Moreover, another object of this invention is to allow
the micro-transer of the tool post in the Y-axis direction
without spoiling the rigidity between the tool post and the
tool post slide by coupling the tool post and the tool post
slide in the compound lathe by means of a coupling mechanism
of this invention, Thus when a key way is to be machined,
correction of error o~ the dimension of the key way resulting
from the abrasion wear of the milling cutter becomes possible,
and as the result, a key way of an accurate width can be
machined.
According to the present invention there is provided in
combination, a pair of mechaniical elements and a coupling
mechanism for coupling the elements together, the mechanism
including a fluid pressure chamber formed in one of said ele-
ments and an elongate member housed in said pressure chamber,
the elongate member being fixed at one end to said one elemer.-
and fixed at its opposite end to the other element so tha~
fluid pressure applied to said chamber causes relative move-
ment between said elements and applies tensile stress to said
member to cause it to stretch in an axial direction said one
element and the elongate member being movably connected to one
~ another near to said opposite end of the elongate member to
permit relative axial movement only.
Reference is now made to the accompanying drawings, in
which:
~igure 1 is a side view schematically showing a compound
lathe;
Figure 2 is a partial cross section showing a coupling
mechanism accordinq to the present invention incorporated
between a tool post and a tool post slide of a compound lathe;
Figure 3 is a block dia~ram showing a displacement quant-
ity control unit for a tool post when coupled to a tool post
slide by a coupling mechanism according to the present in-
. ~, Sl.
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ventiorl;
~ igure ~ is a perspec~ive view schematically showing a
drilling machine incorporating a coupling mechanism according
to the present invention, which couples the column to the
S base; and
Figure 5 is a schematic perspective view of a lathe in-
corporating a coupling mechanism according to the present in-
vention between the tail stock, and its slide, and the tool
post and its slide.
In Figure 1, there is shown a lathe W which is of gener-
ally conventional construction except for the cou~ling mech-
anism between tool post l and a tool post slide 2. The com-
pound lathe W is provided with a bed 3, and is provided with a
chuck mounted on the spindle. A cross slide 5 is mounted on
tl~e bed 3 so as to be slidable in the axial direction of the
spindle, and the tool post slide 2 coupled with the tool post
l is mounted on the cross slide 5 so as to be slidable in a
transverse direction to the axis of the spindle i.e. to the
right or left as shown in Figure 1. The tool post slide 2 i-
made ~o move slidably on the cross sllde 5 by a motor 6. T~l-
tool post l is provided with a tool mounting shaft 7, and -.
milling cutter 3 is mounted on the tool mounting shaft 7, and
the tool mounting shaft 7 is rotatably operated by a motor 9.
The tool post 1 and the tool post slide 2 are coupled by
the coupling mechanism according to this invention as will be
described in detail hereinafter.
In ~igure 2, the coupling mechanism for mutually coupling
the post 1 and slide 2 (which may be generally described as
being machine elements) is shown in detail. The coupling
mechanism inclues a pressure chamber 10 formed in holder 15,
and an elongate, preferably, columnar member 11 that is acted
upon by the fluid pressure in the pressure chamber 10 as a
uniform tensile stress in the axial direction. The holder 15
which forms part of the post 1 is substantially made of rigid
materlal and is fixed to the tip 12 of the columnar member 11
and is interconnected with the base portion 13 of the columnar
member 1~ so as to be relatively shiftable only in the axial
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directioll. This is achieved by the portion 16a of base por-
tion 13 being slidably received in the chamber or by a washer
like spring plate 16. Accordingly, variation of the mutual
micro-positional relationship of the coupled machine elements
1 and 2 is possible by utilizing the elastic deformation of
the columnar member 11 caused by the fluid pressure in the
pressure chamber 10. Since the'base portion 13 of the colum-
nar chamber 11 and the holder 15 are interconnected to be
relatively shiftable only in the axial direction by a washer
like spring plate 16 or by portion 16a, slidingl~ engaging the
chamber wall, the cutting reaction force working in a direc-
tion at right angles to the Y axis is transmitted to the tool
post slide 2, and no bending stress works'on the columnar mem-
ber 11, and therefore, the rigidity in the coupled portion is
assured, and also, an accurate linearity can be maintained
between the fluid pressure in the pressure chamber 10 and dis-
placement quantity of the machine element 1 in the Y axis di-
rection.
r~ex~, this invention will be described by referring to
embodiments shown in Figures 2 and 3.
The columnar member 11 of ~igure 2 is constructed in Such
a way that the base end 14 is fixed to the tool post slide 2
by a bolt (not shown), and the tip 12 is fixed to the tool
post 1 by means of the head member 17. The holding member 15
is integral with the tool post 1, and a cylindrical hole cent-
-- ering around the columnar member 11 ~is formed in the tool
post, and a sleeve 18 is fitted within the cylindrical hole to
: form the pressure chamber 10. The sleeve 18 is mounted so
that the fluid pressure in the pressure chamber 10 does not
work directly onto ~he tool post (which is a casting), and as
a result, it is substantially an integral unit with the holder
15, and its lower end portion is slidable on the base portion
14 of the columnar member 11. ~he base portion 13 of the
columnar member 11 and the holder 15 are interconnected so as
to be movable only in the axial direction of the columnar mem-
ber 11 by means of"the sliding portion 16a,-'but in order to
increase the rigidity of the interlocking portion, the holder
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15 and the base portion 13 of the columnar member 11 are conn-
ected by the washer like spr.ing plate 16. The inside diamet-
ral portion of the spr.ing plate 16 is sandwiched between the
base end 14 of the columnar member 11 and the tool post slide
2, and is fixed to the side of the tool post slide 2, and its
outside diametral portion is sandwiched between the lower end
portion of the holder 15 and the holding member 19, and is
fixed to the side of the holder 15. Reference numerals 20,
21, 22 denote pressure oil supply holes provided in the tool
post slide 2 and the columnar member 11, and numerals 23 and
24 denote liquid sealing units, and numeral 25 shown by
imaginary line denotes a workpiece.
In the foregoing structure~ when the operating pressure
o~ oil supplied to the pressure chamber 10 is high, the press-
ure produces a uniform tensile stress in the axial directionof the columnar member 11. The tool post 1 is displaced by a
micro-quantity in the upper direction in Figure 2 on account
of the resulting elastic distortion of the columnar member 11
so that micro-displacement in the Y 2xis direction can be
applied to the tool mounting shaft 7.
The pressure oil supply unit to the pressure chamber lt
and the control system are shown in Figure 3, and numeral 2~
denotes a cylinder of the pressure oil supply unit, and 27
denotes a plunger moving back and forth in the cylinder 26,
and 28 denotes a screw formed in~egral with the plunger 27,
- and 29 denotes a gear meshed with the screw 28, and 30 denotes
a gear meshed with the gear 29, and 31 denotes a DC motor for
driving the gear 30, and 32 denotes an oil pressure pipe. The
DC motor 31 rotates by the s~rvo control that is operated by
the control unit to be described hereinafter, and rotates the
gear 29 supported b~ the frame (not shown) by means of the
bearing 33, and causes the non-rotating plunger 27 to move
back and forth to change the pressure of the operating oil to
be supplied to the pressure chamber 10, and change the quant-
ity of displacement of the tool post 1 in the Y axis di-
rection. ~ -
I'he quantity of displacement of the tool post 1 is de-
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--6--tected by the differential transformer 34, and is applied to
the differential amplifier 36 through the insulated amplifier
35, and on the other hand, the instruction data applied from
the NC device or other instruction device ~not shown) is app-
lied to the differential amplifier 36 through the D-A convert-
er, and the servo amplifier controls the DC motor 31 by the
differential signal. ~hen the output of the differential
amplifier 36 becomes within a fixed allowable value, the coin-
cidence signal from the comparator 37 is outputted to the in-
struction device, and the position in the Y axis direction ofthe tool post 1 and the tool 8 is set at the instructed pos-
ition.
As described in the foregoing, the position of the tool
post 1 is corrected in the Y axis direction or is displaced,
and machining error due to the thermal deformatlon of the
loaded workpiece 25 or machining error due to the abrasion of
the tool 8 is corrected or machining with accuracy according
to the difference of various fitting dimensions such as a kev
way or the like can be achieved by the displacement of tne
too~ post 1 ir. the Y axis dlrection, but as the uniform ter-
sile stress only is applied to the columnar member 11 by t~e
construction mentioned in the foregoing, the accurate linear
relationship between the pressure of the pressure oil to he
supplied to the pressure chamber 10 and the displacement o~
the tool post 1 is assured whereby the control of the quantity
of displacement can be carried out easily with extreme
accuracy.
The foregoing embodiment is used for correcting or ad-
justing the position of the tool post 1 in the Y axis direc-
tion of a compound lathe W. It will be appreciated that thecoupling mechanism according to the present invention is suit-
able for use in any mechanism or machinery where a high rigid-
ity and accuracy in position of the coupling is required. For
example, the drilling machine B shown in Figure 4 is such that
the column 38 and the base portion 39 are~coupled by the coup-
ling mechanism 40 of this invention, and the angle of the co1-
umn 38 can be adjusted minutely and correctly by supplying oil
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pressure selectively to the respective coupling mechanisms
40..... 40. ~umeral 47 of ~igure 4 denotes the support plate,
and the column 38 is fixed to the support plate 47, and the
support plate 47 and the base 39 are coupled by the coupling
5 mechanisms 40 ....... 40. Also, in the lathe T shown in Figure
5, the tail stock 41 and its tail stock slide 42 are coupled
by using the coupling mechanisms 40 ..... 40 of this invention
in horizontal direction, so that the spindle 43 and the tail
stock 41 may be displaced in minute angle in the horizontal
plane to perform correction of the taper of the workpiece 25
or degree of its cylindrical shape, and moreover, in case the
tool post 44 and the tool post slide 45 are coupled by using
the coupling mechanisms 40 ..... 40 of this invention in hori-
zontal direction, so that the cutting tool ~6 may be stati-
cally or dynamically moved back and forth to correct the d1-
mension difference of the outside diameter of the workpiece
25 or to correct its roundness. Numeral 48 of Figure 5 de-
notes the bed, and 49 denotes the base, and 50 denotes the
machine case in ~hich the spindle drive mechanism i5 built in.
The columnar member 11 ir, the coupling mechanism of thl
lnvention has high rigidity in the axial direction, and the
possible displacement quantity of the coupled machine elemen~s
is less than 1 milimeter. The control of the displacement
quantity is possibly carried out with the accuracy in the
order of 1 micron, and the fluid pressure to be supplied to
the pressure chamber 10 is practically set at high pressure of
about 500 to 700 kg per square centimeter. In this high
pressure fluid as mentioned in the foregoing, the compressing
property by the air to be mixed into the fluid becomes a major
factor of deteriorating the control accuracy of the displace-
ment quantity, particularly, the dynamic control accuracy. In
order to avoid deterioration of control accuracy by the air
present in the fluid, it is desirable to minimize the volume
of the pressure chamber 10. This may be achieved by inserting
a sleeve 51 into the pressure chamber 10 to reduce the volume
of the pressure chamber 10 as shown in the imaginary line in
Figure 2.
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