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Participant

Join Date: Oct 2012
Posts: 3

Frequent Toggle Locking Problem in Injection Molding Machine Chenpet 83

07/08/2014 4:36 PM

i am using chenpet 83 machine in which there is a frequent problem of toggle locking.once the mold is closed , it closes permanently and does not open in natural way.

some other device is required to open the mold.What may be the problem? and what to do to get rid of that????

seeking for answers

Er. GIRDHAR GUPTA

INDIA.

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Guru

Join Date: Oct 2008
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#1

Re: facing frequent toggle locking problem in injection molding machine chenpet 83

07/08/2014 6:21 PM

Toggle machines are relatively simple machines. If you have a tech who knows how they work.

It sounds like you do not have anyone on staff who knows this.

I'm not familiar with this Chinese machine but some mechanism (probably hydraulic cylinders, maybe screws but I doubt it) closes the toggle and it locks, applying clamping pressure to the mold.

That cycle is reversed to open the mold.

It takes considerable pressure to close, and open the toggle.

Odds are good that the control circuit is bad or a solenoid is bad.

There is no way to trouble shoot this on an anonymous, remote forum.

Call the tech service at the manufacturer.

I'm not going to try to help with this, there's no way.

The only thing I can offer is that the clamping pressure is too high causing the toggle to lock. An operator who does not know how to set the clamp pressure may be your problem. Competent operators are very valuable. How are yours?

Get a service tech.

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Guru

Join Date: Aug 2012
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#2
In reply to #1

Re: facing frequent toggle locking problem in injection molding machine chenpet 83

07/08/2014 8:34 PM

Seconded all of the above, with the added question of how good is your maintenance department?

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Power-User

Join Date: Jun 2007
Location: Center of the Known Industrial Universe - TUGGERAH 2259 - Australia
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#3

Re: Frequent Toggle Locking Problem in Injection Molding Machine Chenpet 83

07/08/2014 10:41 PM

Lyn's comment "The only thing I can offer is that the clamping pressure is too high causing the toggle to lock. An operator who does not know how to set the clamp pressure may be your problem" is probably the best clue.

Toggle is usually performed with a double-acting hydraulic cylinder. The full piston area is effectively converted into linear force during clamping.

But the rod cross-sectional area is subtracted from the full piston area during un-clamping with the double-acting cylinder.

Therefore if the mechanical settings create a lock/unlock force requirement which needs the highest possible hydraulic system pressure for toggling the clamp, the same pressure will be unable to un-toggle the clamp, because the reverse action of the cylinder suffers reduced hydraulic area.

Correct the mechanical settings of the toggle, so it does not create such a high force requirement of the toggle clamp/unclamp cylinder.

Mark Bingham
Relativity PL

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#4

Re: Frequent Toggle Locking Problem in Injection Molding Machine Chenpet 83

07/09/2014 2:48 AM

I agree with the above comments, especially about the hydraulic cylinder having lower capacity in the opening direction.

Toggle over centre during clamping (with no material inside the die) creates clamp pressure.

Once material is injected, there is additional pressure that may exceed the hydraulic capacity to unlock the toggle.

This is one case where "bigger is better" does not apply.

Sounds like machine being closed solid, then toggled rather than brought close then toggled for final lock.

Try backing off the "mould close" distance by a fraction and see what is achieved. (Back it out until you get "flash" then creep it forward until flash free parts are achieved.) You will also get longer tool life by less clamp tonnage.

Note also, if over-stressing the clamp system, it is probable that you will get premature failure of the machine tie rods and other related components that are being put into extreme stress by the forces induced.

Is the problem common to multiple tools or just one? (multiple tools would indicate a setting process issue, while a single tool might indicate the tool height has been mofified.)

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