Technical Field
[0001]
The present invention relates to a coolant suctio5 n
device of a machine tool having a coolant discharge
function and a machine tool including the coolant suction
device.
Background Art
10 [0002]
In machining using a machine tool, regardless of
water solubility or oiliness, a coolant is widely used.
Moreover, in a machine tool which includes an automatic
tool changer, in addition to a structure in which a
15 coolant is supplied from a nozzle to a work material, in
many cases, a spindle-through structure in which the
coolant passes through a tool is adopted. Also in any
structure, if the coolant remaining in a pipe is not
removed after supply of the coolant is stopped, the
20 coolant may leak outside the machine when a main shaft
moves, or a problem such as biting may occur due to minute
chips being mixed into the coolant when the tool is
changed.
Citation List
25 Patent Literature
3
[0003]
[PTL 1] Japanese Unexamined Patent Application
Publication No. 8-118198 (Fig. 1)
[PTL 2] Japanese Unexamined Patent Application
Publication No. 11-165235 (Fig. 5 g. 1)
Summary of Invention
Technical Problem
[0004]
In the related art, as a method for removing a
10 coolant remaining in a pipe, there are two methods such as
a method of blowing off the coolant by air blow and a
method of sucking the coolant. In the method of blowing
off the coolant, since foggy coolant floats around the
machine, there is a problem in that health problems or
15 contamination of the machine or a building may occur.
[0005]
Meanwhile, as the method of sucking the coolant, for
example, technologies disclosed in PTLs 1 and 2 are known.
However, the following problems exist in PTLs 1 and 2.
20 For example, PTL 1 discloses a structure in which a path
of a coolant discharged from a pump is switched by a valve
so that the coolant passes through an ejector to generate
negative pressure, and the coolant remaining in a pipe is
sucked (refer to Fig. 1). However, in this structure,
25 since the coolant needs to pass through the inner portion
4
of the ejector, there is a concern that minute chips or a
deteriorated coolant may be clogged, and a breakdown may
occur.
[0006]
The present invention is made in consideration 5 ion of
the above-described problems, and an object thereof is to
provide a coolant suction device and a machine tool
capable of collecting a coolant remaining in a supply pipe
while preventing an ejector from breaking down.
10 Solution to Problem
[0007]
According to a first invention for achieving the
above-described object, there is provided a coolant
suction device that sucks a coolant remaining in a supply
15 pipe after the coolant is supplied to the supply pipe of a
machine tool that discharges the coolant, including: a gas
supply source that supplies a gas; an ejector that
includes an input side connected to the gas supply source
via a first valve; a primary receiving container that
20 includes an upper part connected to a negative-pressure
side of the ejector; a suction pipe that includes one end
connected to the upper part of the primary receiving
container and the other end connected to the supply pipe
via a second valve; and a non-return valve that is
25 connected to a bottom part of the primary receiving
5
container and opens below the primary receiving container,
in which the first valve and the second valve are open,
the gas is supplied from the gas supply source to the
ejector, negative pressure is created inside the primary
receiving container by the ejector, and the coola5 nt
remaining in the supply pipe is sucked into the primary
receiving container via the suction pipe.
[0008]
In a second invention for achieving the above10
described object, in the coolant suction device according
to the first invention, when the first valve and the
second valve are closed, the inner portion of the primary
receiving container may return to the atmospheric pressure,
the non-return valve may open by the weight of the coolant
15 itself sucked into the primary receiving container, and
the coolant may be discharged downward.
[0009]
In a third invention for achieving the abovedescribed
object, in the coolant suction device according
20 to the first or second invention, a storage container that
stores the sucked coolant may be provided below the nonreturn
valve.
[0010]
In a fourth invention for achieving the above25
described object, in the coolant suction device according
6
to any one of the first to third inventions, a filter that
separates gas and liquid may be provided on an output side
of the ejector.
[0011]
In a fifth invention for achieving the 5 e abovedescribed
object, in the coolant suction device according
to any one of the first to fourth inventions, volume of
the primary receiving container may be larger than
capacity inside the supply pipe.
10 [0012]
According to a sixth invention for achieving the
above-described object, there is provided a machine tool
including the coolant suction device according to any one
of the first to fifth inventions.
15 Advantageous Effects of Invention
[0013]
According to the present invention, since a gas is
used to drive an ejector and it is not necessary to cause
a coolant to pass through the inner portion of the ejector,
20 minute chips or a deteriorated coolant is not clogged
inside the ejector, and it is possible to decrease a
breakdown probability of the ejector.
Brief Description of Drawings
[0014]
25 Fig. 1 is a system diagram showing an example of an
7
embodiment of a coolant suction device according to the
present invention.
Fig. 2 is a diagram for explaining suction of a
coolant from a supply pipe with reference to the system
diagram shown in Fig. 5 1.
Description of Embodiments
[0015]
Hereinafter, embodiments of a coolant suction device
and a machine tool according to the present invention will
10 be described with reference to Figs. 1 and 2.
[0016]
(Embodiment 1)
Fig. 1 is a system diagram showing a coolant suction
device according to the present embodiment, and Fig. 2 is
15 a diagram for explaining suction of a coolant from a
supply pipe with reference to the system diagram shown in
Fig. 1.
[0017]
The coolant suction device of the present embodiment
20 is used in a machine tool having a coolant discharge
function, and sucks a coolant remaining in a supply pipe
after discharging of the coolant stops to prevent the
coolant from being leaked.
[0018]
25 First, the discharging of the coolant will be
8
described with reference to Fig. 1. A storage tank 11
which stores a used coolant C is provided in a machine
tool (not shown), and the coolant C is supplied to the
machine tool using a pipe P1 connected to the storage tank
11 and a pump 12 and a motor 13 attached to the pipe 5 e P1.
[0019]
For example, the coolant C is supplied to three
locations such as a work piece, a main shaft core, and a
sub shaft core (for example, an attachment or the like) of
10 the machine tool, and when the coolant C is discharged,
three supply pipes P2a to P2c are connected to the pipe P1.
A valve 14a and a check valve 15a are connected to the
supply pipe P2a for the work piece, a valve 14b and a
check valve 15b are connected to the supply pipe P2b for
15 the main shaft core, and a valve 14c and a check valve 15c
are connected to the supply pipe P2c for the sub shaft
core. The number of the supply systems can be
appropriately increased or decreased according to the
locations for discharging the coolant needed in the
20 machine tool.
[0020]
For example, when the coolant C is supplied to the
work piece to be discharged, the valve 14a is opened by
the control of a control device (not shown), and the
25 coolant C is supplied to the work piece via the supply
9
pipe P2a and is discharged. Similarly, when the coolant C
is supplied to the main shaft core to be discharged, the
valve 14b is opened by the control of the control device,
and the coolant C is supplied to the main shaft core via
the supply pipe P2b and is discharged. In addition, 5 n, when
the coolant C is supplied to the sub shaft core to be
discharged, the valve 14c is opened by the control of the
control device, and the coolant C is supplied to the sub
shaft core via the supply pipe P2c and is discharged.
10 [0021]
In the supply pipes P2a to P2c, branching pipes are
respectively connected to the downstream sides of the
check valves 15a to 15c, and the coolants remaining inside
the supply pipes P2a to P2c on the downstream sides of the
15 check valves 15a to 15c can be sucked by the coolant
suction device described below. Since cracking pressures
of the check valves 15a to 15c are greater than pressure
(negative pressure) generated by suction of the coolant
suction device described below, the check valves 15a to
20 15c are not open while the coolant is being sucked.
[0022]
Next, the coolant suction device of the present
embodiment will be described. The coolant suction device
of the present embodiment also uses an ejector 24. An
25 input pipe T1 is connected to the input side of the
10
ejector 24, a gas supply source 21 for supplying a gas
such as air (compressed air or the like) or gas (nitrogen,
oxygen, or the like), a valve 22 for supplying the gas
from the gas supply source 21 or stopping the supply of
the gas, and an manual valve 23 for adjusting pressure 5 or
a flow rate of the supplied gas are connected to the input
pipe T1.
[0023]
Moreover, the output side of the ejector 24 may open
10 to the atmosphere. However, here, an output pipe T2 is
connected to the output side of the ejector 24, a filter
26 which separates gas and liquid is connected to the
output pipe T2, a discharge pipe T3 is connected to the
lower part of the filter 26, and the discharge pipe T3 is
15 joined with a discharge pipe T6 described below.
[0024]
In addition, a negative-pressure pipe T4 is
connected to the negative-pressure side of the ejector 24,
and the negative-pressure pipe T4 is connected to an upper
20 part of a primary receiving tank 25. In addition, one end
of a suction pipe T5 is connected to the upper part of the
primary receiving tank 25, and the other end of the
suction pipe T5 is connected to each of the branching
pipes P3a to P3c via each of valves 28a to 28c. Moreover,
25 a discharge pipe T6 is connected to the bottom part of the
11
primary receiving tank 25, a check valve 27 which only
opens downward is connected to the discharge pipe T6, the
discharge pipe T3 and the discharge pipe T6 are joined
with each other at the downstream side of the check valve
27, and a discharge port of the joined portion is 5 disposed
above the storage tank 11.
[0025]
The coolant remaining inside the supply pipes P2a to
P2c is sucked using the coolant suction device configured
10 as described above. Here, with reference to Fig. 2, the
suction of the coolant C remaining inside the supply pipe
P2a will be described.
[0026]
As described above, when the coolant C is supplied
15 to the work piece to be discharged, the valve 14 is opened
by the control of the control device, and the coolant C is
supplied to the work piece via the supply pipe P2a and is
discharged. Since the coolant C remains inside the supply
pipe P2a after the discharging of the coolant C stops, the
20 valve 28a and the valve 22 are opened by the control of
the control device in order to suck the coolant C.
[0027]
If the valve 22 is open, the gas is supplied from
the gas supply source 21 to the ejector 24 via the input
25 pipe T1 (flow G1 of gas). If the liquid such as the gas
12
is supplied to the ejector 24, the fluid is ejected at a
high speed from a nozzle provided inside the ejector 24,
negative pressure is generated by an entrainment effect of
the ejected fluid, and thus, other fluid is sucked by the
generated negative pressure and can be discharged. Th5 e
negative-pressure pipe T4 of the ejector 24 is connected
to the primary receiving tank 25, and the ejector 24 sucks
the air inside the primary receiving tank 25 and
discharges the air.
10 [0028]
When the air inside the primary receiving tank 25 is
sucked and discharged by the ejector 24, the inner portion
of the primary receiving tank 25 also is in a negativepressure
state. Although the check valve 27 is connected
15 to the discharge pipe T6 connected to the bottom portion
of the primary receiving tank 25, if the inner portion of
the primary receiving tank 25 is in the negative-pressure
state, since the upstream side of the check valve 27
reaches a negative pressure (pressure smaller than the
20 atmospheric pressure) and the downstream side of the check
valve 27 reaches the atmospheric pressure, a state where
the check valve 27 is closed is maintained. Even when the
inner portion of the primary receiving tank 25 is in the
negative-pressure state by the check valve 27, the
25 surrounding atmosphere or the coolant C does not return to
13
the primary receiving tank 25 from the discharge pipe T6
side.
[0029]
Accordingly, when the inner portion of the primary
receiving tank 25 is in the negative-pressure state, 5 the
coolant C remaining inside the supply pipe P2a is sucked
via the suction pipe T5 connected to the upper part of the
primary receiving tank 25, the valve 28a, the branching
pipe P3a, and the coolant C is collected inside the
10 primary receiving tank 25 (a flow R1 of the coolant C).
In addition, the collected coolant C is temporarily stored
inside the primary receiving tank 25.
[0030]
In this case, since the pressure and the flow rate
15 of the gas supplied from the gas supply source 21 are
constant, capacity (capacity of the remaining coolant C)
inside the supply pipe P2a is obtained in advance, and if
a time for collecting the obtained capacity is obtained,
it is possible to securely and stably collect the
20 remaining coolant C.
[0031]
As described above, here, the filter 26 is connected
to the output pipe T2. If the inner portion of the
primary receiving tank 25 is set to the negative-pressure
25 state by the ejector 24 and the coolant C remaining inside
14
the supply pipe P2a is collected at the primary receiving
tank 25, the coolant C is atomized in the inner portion of
the primary receiving tank 25 by the force of the sucked
coolant C, and thus, mist may be generated. When the mist
is generated inside the primary receiving tank 25, th5 e
mist is discharged to the output pipe T2 side through the
negative-pressure pipe T4 (a flow G2 of the mist).
[0032]
Therefore, gas and liquid are separated by the
10 filter 26 connected to the output pipe T2, and the
separated gas is discharged to the atmosphere through a
mesh portion 26a of the filter 26 (a flow G3 of the gas).
Meanwhile, the separated coolant C returns to the storage
tank 11 via the discharge pipe T3 connected to the lower
15 part of the filter 26 (a flow R2 of the coolant C). In
this way, even when the coolant C becomes mist, the mist
is not leaked to the atmosphere due to the filter 26.
[0033]
As described above, the negative pressure is
20 generated in the ejector 24 using the gas supplied from
the gas supply source 21, and thus, the coolant C does not
flow to the inner portion (particularly, the nozzle which
generates the negative pressure) of the ejector 24. If
the mist of the collected coolant C is generated inside
25 the primary receiving tank 25, the mist only flows to the
15
vicinity of the nozzle. Accordingly, unlike PTLs 1 and 2,
clogging does not occur in the nozzle, and it is possible
to decrease a breakdown probability.
[0034]
After the remaining coolant C is collected insi5 de
the primary receiving tank 25, when the valve 28a and the
valve 22 are closed by the control of the control device,
that is, when the supply of the gas from the gas supply
source 21 stops, the inner portion of the primary
10 receiving tank 25 returns to the atmospheric pressure
state. If so, the check valve 27 is opened by the weight
of the coolant C itself collected inside the primary
receiving tank 25, and thus, the coolant C is
automatically collected in the storage tank 11 via the
15 discharge pipe T6 (a flow R3 of the coolant C). The
cracking pressure of the check valve 27 may be set so that
the check valve 27 is opened by the weight of the coolant
C itself. In this way, here, in order to return the
coolant C from the primary receiving tank 25 to the
20 storage tank 11 using the own weight of the coolant C, a
positional relationship between the primary receiving tank
25 and the storage tank 11 is set so that the primary
receiving tank 25 is positioned at the upper portion and
the storage tank 11 is positioned at the lower portion.
25 [0035]
16
In this way, if the valve 28a and the valve 22 are
open and the ejector 24 is operated, the coolant C
remaining inside the supply pipe P2a is sucked and is
collected inside the primary receiving tank 25.
Thereafter, if the valve 28 and the valve 22 are close5 d,
the coolant C collected inside the primary receiving tank
25 returns to the storage tank 11.
[0036]
This is similarly applied to a case where the
10 coolant C remaining inside the supply pipe P2b or the
supply pipe P2c is sucked and collected, the valve 28b may
open and close along with the valve 22 in the case of the
supply pipe P2b, and the valve 28c may open and close
along with the valve 22 in the case of the supply pipe P2c.
15 [0037]
In addition, the capacity (the capacity of the
remaining coolant C) inside the supply pipe P2a is
obtained in advance, and the volume of the primary
receiving tank 25 is set to be larger than the obtained
20 capacity. If the coolant C remaining inside the supply
pipe P2b or the supply pipe P2c is sucked and collected
along with the coolant C remaining inside the supply pipe
P2a, or the coolant C remaining inside both the supply
pipe P2b and the supply pipe P2c is sucked and collected
25 along with the coolant C remaining inside the supply pipe
17
P2a, the capacities of the supply pipes are obtained to be
summed, and the volume of the primary receiving tank 25
may be set to be larger than the summed capacities.
[0038]
In addition, since a pressure 5 (for example,
approximately 3Mpa) required for the discharging is
applied to the pipes P1 to P3 when the coolant C is
discharged, the pipes P1 to P3 need to be high-pressure
pipes capable of enduring the pressure. However, the
10 pipes related to the suction of the coolant C,
specifically, the pipes T1 to T5 need not be high-pressure
pipes since the pipes are not related to the discharge of
the coolant C. The corresponding pressure range of each
of the pipes T1 to T5 may be a range between the negative
15 pressure and the supply pressure (for example,
approximately 0.5 MPa) of the gas.
[0039]
In the devices shown in PTLs 1 and 2, there are
concerns that the following problems may occur in addition
20 to the breakdown of the ejector. For example, in the
devices shown in PTLs 1 and 2, a suction force of the
ejector is dependent on characteristics such as the
discharge pressure of the pump. In addition, since the
pump for discharging the coolant is used as it is and the
25 coolant is supplied to the ejector by switching the supply
18
paths of the coolant, the supply pressure of the coolant
applied to the ejector is not appropriate, and waste in
the amount of power consumption of the pump increases. In
addition, the pipe for sucking the coolant also needs to
be a high-pressure pipe to endure the supply pressure 5 of
the coolant. In addition, since it is necessary to supply
a large amount of coolant to drive the ejector and to
collect the used coolant in the tank, mist may be also
generated in the tank which collects the coolant.
10 [0040]
On the other hand, in the coolant suction device of
the present embodiment, as described above, since the gas
is used to drive the ejector, it is possible to decrease
the breakdown probability, to stabilize the suction force
15 of the ejector, and to decrease the waste based on the
amount of power consumption. In addition, the pipe for
sucking the coolant need not be the high-pressure pipe,
and it is possible to prevent occurrence of the mist since
it is enough to only collect the coolant remaining in the
20 pipe.
Industrial Applicability
[0041]
The present invention is suitable for a machine tool
having a coolant discharge function.
25 Reference Signs List
19
[0042]
11: storage tank (storage container)
12: pump
21: gas supply source
22: valve (first valv5 e)
24: ejector
25: primary receiving tank (primary receiving
container)
26: filter
10 27: check valve (non-return valve)
28a to 28c: valve (second valve)

I/We Claim:
[Claim 1]
A coolant suction device that sucks a coolant
remaining in a supply pipe after the coolant is 5 supplied
to the supply pipe of a machine tool that discharges the
coolant, comprising:
a gas supply source that supplies a gas;
an ejector that includes an input side connected to
10 the gas supply source via a first valve;
a primary receiving container that includes an upper
part connected to a negative-pressure side of the ejector;
a suction pipe that includes one end connected to
the upper part of the primary receiving container and the
15 other end connected to the supply pipe via a second valve;
and
a non-return valve that is connected to a bottom
part of the primary receiving container and opens below
the primary receiving container,
20 wherein the first valve and the second valve are
open, the gas is supplied from the gas supply source to
the ejector, negative pressure is created inside the
primary receiving container by the ejector, and the
coolant remaining in the supply pipe is sucked into the
25 primary receiving container via the suction pipe.
21
[Claim 2]
The coolant suction device according to claim 1,
wherein when the first valve and the second valve
are closed, the inner portion of the primary receiving
container returns to the atmospheric pressure, the non5 -
return valve is opened by the weight of the coolant itself
sucked into the primary receiving container, and the
coolant is discharged downward.
[Claim 3]
10 The coolant suction device according to claim 1 or 2,
wherein a storage container that stores the sucked
coolant is provided below the non-return valve.
[Claim 4]
The coolant suction device according to any one of
15 claims 1 to 3,
wherein a filter that separates gas and liquid is
provided on an output side of the ejector.
[Claim 5]
The coolant suction device according to any one of
20 claims 1 to 4,
wherein volume of the primary receiving container is
larger than capacity inside the supply pipe.
22
[Claim 6]
A machine tool comprising the coolant suction device
according to any one of claims 1 to 5.