US3748427A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Depth stop sensing device for an electrical discharge machine
Assignee: A&A Engineering Co
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Filing: 1971-08-16
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Granted: 1973-07-24
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Expires: 1991-08-16
Abstract
Abstract A depth stop sensing device used in an electrical discharge machine which cuts holes of a specified depth in a conductive workpiece by eroding the workpiece with a discharge cutting current includes a tool electrode having a cutting porjection that is lowered into cutting relationship with the workpiece by a ram assembly. As a cutting current is applied by the tool electrode to the workpiece, a hole is formed in the workpiece in the same shape as the cutting projection. When the hole is cut to the specified depth, a sensing projection on the tool electrode supplies a signaling current to a sensing finger disposed adjacent to the workpiece and positioned at the specified depth. A triggering circuit coupled to the sensing finger receives the signaling current from the sensing finger and initiates the retraction of the ram assembly and thereby the tool electrode from the workpiece so that the hole is not cut beyond the specified depth.
Inventors
- 👤 R Baldwin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 09:10
CPC Classifications
B; B23; B23H; B23H7/00; B23H7/26
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
215 words
In an electrical discharge machine used in cutting holes of a required depth in a workpiece by eroding the workpiece with a discharge cutting current, a depth stop sensing device comprising: a tool means having an electrode portion terminating in a cutting surface through which is supplied the discharge cutting current to said workpiece and a contact portion terminating in a signaling surface, said signaling surface being located in the same plane as said cutting surface; a ram means to which said tool means is attachable, said ram means operable to place said electrode portion of said tool means in cutting relationship with said workpiece and to move said electrode portion into said workpiece during the cutting of said holes, and operable to retract said tool means from said workpiece after said holes are cut to the required depth; a sensing means mountable so as to indicate the required depth of said holes, said sensing means making electrical contact with said contact portion of said tool means when said electrode portion has cut the hole to the required depth; and a triggering circuit mEans responsive to said sensing means making electrical contact with said contact portion of said tool means for placing into operation said ram means to retract said tool means from said workpiece.
Claim 2
Dependent Claim
215 words
In an electrical discharge machine used in cutting holes of a required depth in a workpiece by eroding the workpiece with a discharge cutting current, a depth stop sensing device comprising: a tool means having an electrode portion terminating in a cutting surface through which is supplied the discharge cutting current to said workpiece and a contact portion terminating in a signaling surface, said signaling surface being located in the same plane as said cutting surface; a ram means to which said tool means is attachable, said ram means operable to place said electrode portion of said tool means in cutting relationship with said workpiece and to move said electrode portion into said workpiece during the cutting of said holes, and operable to retract said tool means from said workpiece after said holes are cut to the required depth; a sensing means mountable so as to indicate the required depth of said holes, said sensing means making electrical contact with said contact portion of said tool means when said electrode portion has cut the hole to the required depth; and a triggering circuit mEans responsive to said sensing means making electrical contact with said contact portion of said tool means for placing into operation said ram means to retract said tool means from said workpiece.
Claim 3
Dependent Claim
86 words
The depth stop sensing device as set forth in claim 1 wherein said triggering circuit means includes: at least one normally nonconductive controlled conduction device coupled to said sensing means, said controlled conduction device being rendered conductive when said sensing means makes electrical contact with said contact portion of said tool means; and responsive circuit means coupled to said controlled conduction device, said responsive circuit means actuating said ram means to retract said tool means from said workpiece when said controlled conduction device is rendered conductive.
Claim 4
Dependent Claim
41 words
The depth stop sensing device as set forth in claim 1 wherein said sensing means has a generally elongated finger portion having a contact surface which makes electrical contact with said signaling surface of said contact portion of said tool means.
Claim 5
Dependent Claim
27 words
The depth stop sensing device as set forth in claim 3 wherein the finger portion of said sensing means is electrically insulated from said electrical discharge machine.
Claim 6
Dependent Claim
189 words
In electrical discharge machine used in cutting holes of a required depth in a workpiece by eroding the workpiece with a discharge cutting current, a depth stop sensing device comprising: a tool means having a projecting electrode means through which is supplied a cutting current to said workpiece and a projecting contact means which is generally parallel to and spaced apart from said projecting electrode means; a ram means to which the tool means is attachable, said ram means capable of placing said projecting electrode means of said tool means into cutting relationship with said workpiece and capable of retracting said tool means from said workpiece; a sensing means mountable adjacent to said workpiece, said sensing means having a contact surface positioned at the required depth of said holes and capable of receiving a signaling current from said projecting contact means when said projecting electrode means has cut a hole in the workpiece to the required depth; and a triggering circuit means responsive to said sensing means receiving said signaling current from said projecting contact means to cause said ram means to retract said tool means from said workpiece.
Claim 7
Dependent Claim
189 words
In electrical discharge machine used in cutting holes of a required depth in a workpiece by eroding the workpiece with a discharge cutting current, a depth stop sensing device comprising: a tool means having a projecting electrode means through which is supplied a cutting current to said workpiece and a projecting contact means which is generally parallel to and spaced apart from said projecting electrode means; a ram means to which the tool means is attachable, said ram means capable of placing said projecting electrode means of said tool means into cutting relationship with said workpiece and capable of retracting said tool means from said workpiece; a sensing means mountable adjacent to said workpiece, said sensing means having a contact surface positioned at the required depth of said holes and capable of receiving a signaling current from said projecting contact means when said projecting electrode means has cut a hole in the workpiece to the required depth; and a triggering circuit means responsive to said sensing means receiving said signaling current from said projecting contact means to cause said ram means to retract said tool means from said workpiece.
Claim 8
Dependent Claim
43 words
The depth stop sensing device as set forth in claim 5 wherein said projecting electrode means has a first end surface and said projecting contact means has a second end surface, said first and second end surfaces being maintained in the same plane.
Claim 9
Dependent Claim
33 words
The depth stop sensing device as set forth in claim 5 wherein said projecting electrode means and said projecting contact means form a generally U-shaped cavity at one end of said tool means.
Claim 10
Dependent Claim
37 words
The depth stop sensing device as set forth in claim 5 including: a holding device for said sensing means so that said sensing means can be mountable adjacent to said workpiece at any depth along said workpiece.
Claim 11
Dependent Claim
43 words
The depth stop device as set forth in claim 8 including: a dielectric coolant oil into which said workpiece, said sensing means, said holding device and a portion of said tool means are submerged during the cutting of a hole in said workpiece.
Claim 12
Dependent Claim
55 words
The depth stop device as set forth in claim 9 wherein said projecting electrode means has a first end surface and said projecting contact means has a second end surface and wherein said tool means has oil passages through which said dielectric oil flows, said passages having openings at said first and second end surfaces.
Claim 13
Dependent Claim
23 words
The depth stop device as set forth in claim 8 including: mounting means onto which said workpiece and said holding device are mountable.
Claim 14
Dependent Claim
18 words
The depth stop device as set forth in claim 8 wherein said mounting means is a magnetic chuck.
Claim 15
Dependent Claim
44 words
The depth stop sensing device as set forth in claim 1 wherein said sensing means is mountable adjacent said workpiece and said contact portion is positioned adjacent to said workpiece as said electrode portion moves into said workpiece during the cutting of said holes.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-07-23 | 1977-01-22 | 1977-07-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-23 | 1981-01-22 | 1981-07-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-23 | 1985-01-22 | 1985-07-24 | $7700.00 | Window Closed / Lapsed |