US3704973A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electro-hydraulic means for opening and closing injection molds
Assignee: Husky Manufacturing and Tool Works Ltd
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Filing: 1971-06-08
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Granted: 1972-12-05
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Expires: 1991-06-08
Abstract
Abstract The movable platen of an injection-molding machine is rigid with a nonrotatable lead screw engaged by a rotatable drive nut which is splined to a tubular input shaft surrounding the rear end of the lead screw. A cylinder on the machine frame carries an axially movable piston which, upon a stopping of shaft rotation in the mold-closed position, is brought to bear under hydraulic pressure against the nut to clamp the mold between the platens against the tie bars anchored to the frame. The input shaft is powered by a reversible two-speed motor which is switched to lowspeed operation in a terminal phase of a lead-screw stroke to absorb excess energy in a nondissipative manner.
Inventors
- 👤 Robert Morrison Renfrew
- 👤 Peter Leon Rees
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 14:57
CPC Classifications
B; B29; B29C; B29C45/00; B29C45/17; B29C45/64; B29C45/68; B29C45/66; B29C2045/1784; B29C2045/1792; B29C2045/1794
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
218 words
In an injection-molding machine comprising a frame, a substantially stationary platen on said frame adapted to support a first mold portion, a set of tie bars rigid with said frame having forward ends anchored to said stationary platen, and a movable platen slidable along said tie bars and adapted to support a second mold portion, the combination therewith of mechanism for reciprocating said movable platen on said tie bars between an advanced position of mold closure and a retracted position of mold opening, said mechanism comprising: a lead screw parallel to said tie bars, said lead screw having a rear end remote from said platens and a front end nonrotatably secured to said movable platen for axial reciprocation therewith; a nut threadedly engaging said lead screw, said nut being rotatably mounted on said frame, reversible electric drive means with a relatively high and a relatively low operating speed for rotating said nut to advance and retract said lead screw together with said movable platen; and switchover means controlled by said lead screw for operating said drive means at said relatively high speed over the major part of a reciprocating stroke of said movable platen and for switching to low-speed operation in a terminal phase of such stroke to decelerate said nut with reconversion of kinetic to electric energy.
Claim 2
Dependent Claim
218 words
In an injection-molding machine comprising a frame, a substantially stationary platen on said frame adapted to support a first mold portion, a set of tie bars rigid with said frame having forward ends anchored to said stationary platen, and a movable platen slidable along said tie bars and adapted to support a second mold portion, the combination therewith of mechanism for reciprocating said movable platen on said tie bars between an advanced position of mold closure and a retracted position of mold opening, said mechanism comprising: a lead screw parallel to said tie bars, said lead screw having a rear end remote from said platens and a front end nonrotatably secured to said movable platen for axial reciprocation therewith; a nut threadedly engaging said lead screw, said nut being rotatably mounted on said frame, reversible electric drive means with a relatively high and a relatively low operating speed for rotating said nut to advance and retract said lead screw together with said movable platen; and switchover means controlled by said lead screw for operating said drive means at said relatively high speed over the major part of a reciprocating stroke of said movable platen and for switching to low-speed operation in a terminal phase of such stroke to decelerate said nut with reconversion of kinetic to electric energy.
Claim 3
Dependent Claim
87 words
The combination defined in claim 1 wherein said nut and said drive means are mounted on said frame with limited axial mobility, further comprising actuating means operable by fluid pressure, upon deactivation of said drive means in said advanced position of said movable platen, to bear upon said nut and said drive means in a forward direction for clamping said mold portions tightly between said platens, said actuating means including a cylinder formed by said frame and a non-rotatable piston in said cylinder operatively engaging said nut.
Claim 4
Dependent Claim
33 words
The combination defined in claim 1 wherein said drive means comprises a rotor coaxial with said nut and positively coupled therewith for joint rotation, and a stator on said frame surrounding said rotor.
Claim 5
Dependent Claim
24 words
The combination defined in claim 3 wherein said rotor is provided with a tubular extension engaging said nut with freedom of relative axial displacement.
Claim 6
Dependent Claim
34 words
The combination defined in claim 2, further comprising brake means on said frame for arresting said rotor and switch means effective in a limiting position of said movable platen for actuating said brake means.
Claim 7
Dependent Claim
36 words
The combination defined in claim 5 wherein said brake means comprises a tubular member embracing said nut with relative axial mobility and coupled therewith for joint rotation, and coacting elEments on said piston and said member.
Claim 8
Dependent Claim
33 words
The combination defined in claim 6 wherein said coacting elements are two sets of interleaved annular foils, said brake means further comprising electromagnetic coil means for exerting a clamping pressure upon said foils.
Claim 9
Dependent Claim
57 words
The combination defined in claim 1 wherein said drive means comprises a polyphase alternating-current motor with a plurality of stator windings alternately connectable by said switch means to a polyphase power supply for energization in a high-field-velocity constellation with a relatively small number of poles and in a low-field-velocity constellation with a relatively large number of poles.
Claim 10
Dependent Claim
37 words
The combination defined in claim 1 wherein said switchover means comprises a pair of switches on said frame positioned to be tripped by said movable platen upon its approach of said advanced and said retracted position, respectively.
Claim 11
Dependent Claim
59 words
The combination defined in claim 1, further comprising protective switch means actuatable by said platens in said advanced position upon complete mold closure, programming means for normally reversing said drive means after a predetermined injection interval, and circuit means effective in said advanced position in the unactuated state of said protective switch means for immediately reversing said drive means.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-12-05 | 1976-06-05 | 1976-12-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-12-05 | 1980-06-05 | 1980-12-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-12-05 | 1984-06-05 | 1984-12-05 | $7700.00 | Window Closed / Lapsed |