Press and safety latch therefor

• US 4,007,679 A
• Filed: 03/22/1976
• Issued: 02/15/1977
• Est. Priority Date: 09/22/1975
• Status: Expired due to Term

• Current Assignee: Cincinnati Milacron Incorporated (Milacron Incorporated)
• Original Assignee: Cincinnati Milacron Incorporated (Milacron Incorporated)
• Inventors: Edwards, Bobbie Lee
• Primary Examiner(s): Wilhite, Billy J.
• Application Number:
  US05/669,209
• Time in Patent Office: 330 Days
• Field of Search: 100/53, 100/99, 100/231, 100/295, 425/151, 425/153, 425/409, 425/411, 425/451.9, 192/129 R, 192/129 A, 192/129 B
• US Class Current: 100/342
• CPC Class Codes: B29C 2037/94 Safety devices
• CPC Class Codes: B29C 33/20 Opening, closing or clamping
• CPC Class Codes: B29C 33/26 by pivotal movement
• CPC Class Codes: B29C 44/428 Mould constructions; Mould supporting equipment
• CPC Class Codes: B29C 67/246 Moulding high reactive monomers or prepolymers, e.g. by reaction injection moulding [RIM], liquid injection moulding [LIM] casting monomers B29C39/006, mixing construction B29B7/74
• CPC Class Codes: B29K 2075/00 Use of PU, i.e. polyureas or polyurethanes or derivatives thereof, as moulding material

Abstract

A press mechanism that is powered by hydraulic, electrical and/or pneumatic means is provided with an improved ratchet and pawl machine which acts as a fail-safe device should any of the power means fail to lock the press parts in place. The fail-safe device includes a ratchet in the form of a circular or arcuate segment mounted with its circular center substantially coaxial with one of the turning parts of the mechanism or press, a pawl having a single tooth and a circular arcuate peripheral part that acts as a journal bearing and which in turn is supported by a pawl bearing which in turn is secured to a stationary part of the mechanism and has an arcuate journal which receives and supports the pawl therein. Tremendous load carrying capacity is thus achieved because of the large bearing area provided by the pawl bearing and the positioning of the respective ratchet and pawl teeth to employ a surface rather than point contact. An advantage of this structure is that the ratchet does not have to be backed off in order to move or continue moving one part of the mechanism.

Claims

1. An improved ratchet and pawl machine to prevent one part of a press or like mechanism from accidentally swinging to a home position about a first axis and relative to another part, which machine comprises

a ratchet adapted for securing in fixed relation to said one part and having a plurality of equally spaced teeth arranged along an arc that is coaxial with said first axis;

a pawl adapted for pivoting about a second axis and which is peripherally mainly defined by an arcuate bearing surface coaxial with said second axis, a tooth, and a neutral surface, the tip of said tooth being at a radius from said second axis less than the radius of said arcuate bearing surface; and

a pawl bearing for said pawl and which is fixedly secured to said another part and has an arcuate bearing surface shaped and sized to receive the pawl arcuate bearing surface;

said pawl bearing receiving said pawl arcuate bearing surface and supporting said pawl to revolve about said second axis with its tooth located to engage the teeth on said ratchet;

the sum of the ratchet root radius and the pawl tooth tip radius being greater than the distance between said first axis and said second axis.

2. A machine according to claim 1, further comprising:

bias means to urge said pawl tooth into engagement with the space between said teeth.

3. A machine according to claim 2, wherein said bias means is a spring mounted to constantly urge as aforesaid.

4. A machine according to claim 2, further comprising machine power means to withdraw said pawl tooth out of engagement with said ratchet against the urging of said bias means.

5. A machine according to claim 2, further comprising a machine power means that includes an electrical solenoid connected between said pawl and said another part to withdraw said pawl tooth out of engagement with said ratchet when energized.

6. A machine according to claim 2, further comprising a machine power means that includes an pneumatic cylinder connected between said pawl and said another part to withdraw said pawl tooth out of engagement with said ratchet when energized.

7. A machine according to claim 1, further comprising machine power means to disengage said pawl tooth out of engagement with said ratchet.

8. A mechanism that includes the ratchet and pawl machine of claim 1 and further comprises mechanism power means to turn said one part about said first axis relative to said another part and toward and away from a home position.

9. A mechanism according to claim 8, wherein said mechanism power means is a double acting hydraulic cylinder.

10. A mechanism according to claim 8, wherein said another part remains stationary and supports the other elements recited so that said one part is moved against gravity when turned by said mechanism power means about said first axis in a direction away from home and so that gravity would cause the return of said one part to a home position were the said mechanism power means to fail and were said ratchet and pawl machine absent.

11. A mechanism according to claim 8, further comprising

bias means to urge said pawl tooth into engagement with the space between said teeth.

12. A mechanism according to claim 11, further comprising

machine power means to withdraw said pawl tooth out of engagement with said ratchet against the urging of said bias means.

13. A clamp or press that constitutes the mechanism according to claim 8, wherein said one part comprises a swingable frame assembly having trunions upon which such assembly is revolvably supported, said first axis is generally horizontal and extends through said trunnions, said another part is a pedestal and floor plate assembly that revolvably receives said trunnions, the home position is that assumed when the frame is permitted freely to swing about said axis to a predetermined position at one end of the arc through which said frame has swung, and wherein said pawl bearing is fixed to said pedestal.

14. A clamp or press that constitutes the mechanism according to claim 8 wherein said one part comprises a swingable platen suitable for mounting a mold thereon and having journals upon which such platen is revolvably supported, said first axis being generally horizontal and extending through said journals, said another part is a frame assembly that revolvably receives said journals, the home position is that assumed when the platen is permitted freely to swing about said axis to a position at one end of the arc through which said platen has swung and wherein said pawl bearing is fixed to said frame.

15. An improved machine according to claim 1, wherein said pawl is revolvably secured on center by a pin member into said another part around which pin is a resilient journal member there being sufficient pin to pawl play and resilience of said journal bearing to allow said pawl bearing surface to engage the mating surface on said pawl bearing.

16. An improved machine according to claim 1, wherein said pawl bearing has a key formed integrally therewith and located with a longitudinal dimension approximately normal to the force received on the pawl bearing from said ratchet when the pawl tooth is engaged with said ratchet.

17. An improved machine according to claim 1, wherein said ratchet teeth are substantially straight sided and are spaced apart by substantially V-shaped spaces arranged along said arc and said pawl tooth is substantially straight sided and has an included angle substantially that of each said space whereby surface to surface engagement of the pawl tooth and ratchet tooth areas is facilitated.