U.S. patent application number 09/865536 was filed with the patent office on 2001-12-13 for method and apparatus for detecting mis-stripping in a punch press machine.
This patent application is currently assigned to Nisshinbo Industries, Inc.. Invention is credited to Kono, Kazumi.
Application Number | 20010049954 09/865536 |
Document ID | / |
Family ID | 18664090 |
Filed Date | 2001-12-13 |
United States Patent
Application |
20010049954 |
Kind Code |
A1 |
Kono, Kazumi |
December 13, 2001 |
Method and apparatus for detecting mis-stripping in a punch press
machine
Abstract
A method and apparatus for detecting the presence of
mis-stripping uses a sensor function section free from operation
sensibility variation or destruction due to vibration, impact or
the like. Only a ram head in a punch press is provided in an
electrically insulated state on the machine side and a low voltage
is applied to the ram head. Grounding and conduction of the ram
head to the machine side through punch tools is detected when the
ram head is in contact with the punch tools, nonconduction is
detected when the ram head and punch tools are not in contact, and
the nonconduction time is determined to be mis-stripping.
Inventors: |
Kono, Kazumi;
(Higashi-kunisaki-gun, JP) |
Correspondence
Address: |
ARMSTRONG,WESTERMAN, HATTORI,
MCLELAND & NAUGHTON, LLP
1725 K STREET, NW, SUITE 1000
WASHINGTON
DC
20006
US
|
Assignee: |
Nisshinbo Industries, Inc.
Tokyo
JP
|
Family ID: |
18664090 |
Appl. No.: |
09/865536 |
Filed: |
May 29, 2001 |
Current U.S.
Class: |
72/31.01 |
Current CPC
Class: |
B21D 45/006 20130101;
B21D 55/00 20130101 |
Class at
Publication: |
72/31.01 |
International
Class: |
B21C 051/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 30, 2000 |
JP |
2000-159813 |
Claims
What is claimed is:
1. A method for detecting mis-stripping in a punch press machine,
comprising; operating a punch press having a ram head to strike a
punch tool, the ram head being electrically insulated from the
punch press machine; applying a weak current to the ram head, and
determining the presence or absence of mis-stripping by detecting
contact or non contact between said ram head and punch tool by
detecting presence or absence of flow of said current.
2. The method for detecting mis-stripping in a punch press machine
as defined in claim 1, wherein said weak current is a direct
current of about 24V.
3. A method for detecting mis-stripping in a punch press machine,
comprising: providing a ram head of a punch press that is
electrically insulated from the punch press machine; applying an
electric current of low voltage to the ram head, at a return upward
stop position of a punch tool, detecting grounding and conduction
of the ram head to the machine through the punch tool when said ram
head is in contact with the punch tool, and detecting non
conduction when the ram head and the punch tool is not in contact,
where the non conduction time is judged to be mis-stripping.
4. The method of detecting mis-stripping in a punch press machine
as defined in claim 3, wherein said electric current is of about
24V.
5. A detection apparatus for detecting mis-stripping in a punch
press machine having a ram for contacting punch tools, comprising:
a ram head having bores therethrough; fasteners passing through
said bores and securing the ram head to the ram; electrical
insulation disposed between the ram and the ram head; further
electrical insulation disposed in the bores between the fasteners
and the ram head; and an electrical conductive member conductively
attached to the ram head; such that when the ram head contacts the
punch tools an electric current supplied to the electrically
conductive member will flow to the punch tools.
6. A detection apparatus for detecting mis-stripping in a punch
press machine having a ram for contacting punch tools as defined in
claim 5, wherein the fasteners are threaded bolts passing through
the bores of the ram head and threadedly engaged in screw-holes in
the ram.
7. A detection apparatus for detecting mis-stripping in a punch
press machine as defined in claim 6, wherein the screw holes are
provided in a concave mount seat of the ram and the ram head seats
in said concave mount seat.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a method and apparatus for
detecting mis-stripping in a punch press machine.
[0003] 2. Description of Related Art
[0004] In the punch press processing, when continuous punching is
performed, a proper stripping of punch tools is distinguished from
mis-stripping, by detecting whether or not the punch tool is
separated from the punched work piece, by the contact or separation
between the ram head and the punch tools during the upward (return)
movement of the punch tools. That is because, in mis-stripping, if
the work piece is moved, damage to tools and to the work piece can
result, thereby resulting in poor manufacturing.
[0005] Prior methods for detecting whether or not punch tools are
in contact with the ram head, include a method of attaching a metal
round bar (called an area bar) bent in U from the side to the
bottom of a ram head, distinguishing electrical conduction or non
conduction by contact/non contact between the area bar (ram head)
and the punch tools thereby determining whether or not
mis-stripping is present.
[0006] Another existing method uses an optical fiber sensor
attached to the ran head, adjusting the same so that the optical
axis of the sensor passes the ram head bottom, and determining the
presence or absence of contact between the bottom of the ram head
and the top face of the punch tool by whether or not the sensor
optical axis is connected by the ram head and the punch tools, and
thereby determines the present or absence of mis-stripping.
[0007] However, all of the aforementioned prior methods are
embodiments wherein a means for detecting mis-stripping is attached
outside the ram head or punch tools in a punch press machine by a
mechanical post attachment structure. Such an arrangement is often
complicated and, moreover, assembly and maintenance thereof are
difficult. Problems, as mentioned above, are similar in the case
when the punch press machine is a turret punch press machine.
[0008] Particularly, in the prior art, the member serving as a
sensor is provided in a movable portion of the ram head or in the
vicinity thereof by exterior attachment. Therefore, the sensor
function member is fragile and easily susceptible to vibration or
impact of the punch press machine, and the sensibility of the
sensor adjusted beforehand tends to vary due to deviation of the
optical axis for an optical member and the deviation of the contact
position for an electric member. In addition to these inherent
problems, such an arrangement can not be applied to certain forms
of tools used for a punch press machine (for example, in case of
wheel tool, the punch tools rotates in contact section, inhibiting
such use).
[0009] In view of problems of the prior art as mentioned above, the
present invention provides a method and apparatus for detecting the
presence of mis-stripping in a punch press using a sensor function
section free from variation due to operation or destruction due to
vibration, impact or the like, by a structure housing a portion
serving as a sensor in a structure of a punch press machine.
SUMMARY OF THE INVENTION
[0010] The method of the invention having an object to resolve the
aforementioned problems includes providing a punch press with only
a ram head thereof electrically insulated from a machine side and
applying a low voltage to the ram head. The grounding and
conduction of the ram head to the machine side through the punch
tools is detected when the ram head is in contact with the punch
tools, nonconducting is detected when the ram head and the punch
tools are not in contact, and the nonconducting is judged to be
mis-stripping.
[0011] The mis-stripping detection apparatus for performing the
aforementioned method includes a ram and a ram head in a punch
press made as a joint structure by bolting, electrical insulation
between the ram and ram head at the joint portion of the ram and
the ram head, and electrical insulation between the contact portion
of a bolt used for joining the ram and the ram head, and wiring for
applying a low voltage to the ram head. The conduction or
disconnection of an electric circuit formed by the ram head
including the wiring and the punch tools side is detected.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. I is a cross section of essential parts including a ram
head and punch tools of a punch press machine to which a method of
the present invention is applied; and
[0013] FIG. 2 is a cross section of the ram head of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0014] Next, embodiments of the present invention will be described
referring to the accompanying drawings. FIG. 1 is a cross section
of essential parts of the present apparatus including a ram head
and punch tools of a punch press machine to which the method of the
invention is applied, and FIG. 2 is a cross section of the ram head
of FIG. 1.
[0015] In FIG. 1, 1 denotes a ram of a punch press machine which
performs a reciprocal stroke movement in an upward and downward
direction during press operation by means of a conventional driving
source such as a hydraulic cylinder or the like. The lower end
section of the ram 1 is formed as a mount seat 2 for a ram head 3,
having a downwardly directed concave shape.
[0016] The ram head 3 has a striking section 3a on the right in the
example shown in the drawings, with an upper part formed in a joint
section 3b (FIG. 2) to be engaged in the downwardly directed
concave mount seat 2. A plurality of bolt holes 3c are formed in
the ram head 3 for insertion of connection bolts 4 in a direction
parallel to the stroke direction. The ram head 3 is connected to
the mount seat 2 in the ram 1 by means of bolts 4 inserted in the
holes 3c.
[0017] Electrical insulation members 5a and 5b are disposed in the
ram head 3 at an upper top end face and around the joint section 3b
with the ram 1, and electrical insulation members 6a and 6b for the
bolts 4 are disposed at the side faced to a head 4a and a shaft 4b
of the bolts 4 in bolt holes 3c in which the bolt 4 is to be
inserted.
[0018] The ram head 3 is attached to the ram 1, namely to the
machine side of the punch press machine, in an electrically
insulated state, by engaging the ram head 3 to the mount seat 2 of
the ram 1, driving a screw 4c of the bolt 4 in a screw hole 2a of
the mount seat 2, positioning the aforementioned electrical
insulation members 5a, 5b, 6a and 6b, and tightening the bolt
4.
[0019] In the present invention, an electrical conductive member,
such as electric lead 8, is attached via a conductive bracket 7 of
an inversed L-shape to a side (left side in the example of the
drawing) of the aforementioned ram head 3 which has been provided
in an electrically insulated state, and is designed so as to apply
a direct current of 24V, as an example, to the lead 8. By so doing,
when the bottom of the striking section 3a of the ram head 3 is in
contact with the top face of the punch tools 9 placed just under
the ram head 3 at the return upward stop position of the punch
tools 9 after operation, the current applied to the lead 8 is
grounded to the punch press machine via the punch tools 9.
Therefore, in the case where a detector (not shown) such as ampere
meter is interposed between a power source (not shown) and the lead
8, the electric conduction, i.e., the contact between the ram head
3 and the punch tools 9 and the strip completion by the punch tools
9 are detected. If the ram head 3 and the punch tools 9 are not yet
in contact, the current does not flow, and strip incompletion is
detected. Further, even when the current is not detected
immediately at the return upward stop position of the punch tools
9, it may be arbitrarily set to permit detecting of strip
completion in the case where the current is detected within a
predetermined period of time. Note that, in FIG. 1, reference
numeral 10 denotes a holder (or turret) of the punch tools 9 and W
denotes a work piece.
[0020] The present invention is as mentioned above, and when the
punch press processing is performed by providing a ram head
striking punch tools with its attachment area electrically
insulated from the machine and applying a weak current to the ram
head, the presence or absence of mis-stripping is determined by
detecting contact or non-contact between the ram head and punch
tools by the absence or flow of current. Therefore, there is no
deviation of detection sensibility under the influence of vibration
and impact, no damage to the sensor member by the punch tools
rotation and no other problems such as are encountered by the
conventional detecting methods in which an electric connection or
an optical electric member functioning as a sensor is provided in
the vicinity of the ram head by a post attachment structure.
* * * * *