.How can I understand the meaning correctly?
I guess it is possible to get two meanings as you understand.
" The opposition parties combined to drive the Prime Minister out of office."
This sentence seems to have the meaning of purpose in my guess. The parties combined with the purpose of driving the Prime Minister out of office, and then we can't know it is successful yet. So it may be the use of purpose of to - infinitive.
but the below,
" The two car makers combined to form a new company." purpose
The forming of a new company did not instigate the merging. Reason usually comes before the happening. In this sentence, 'to form a new company' is the purpose of the merging. A merging of companies is usually a planned action. To form a new company, that is why they merged.
it is not sure whether it is the use of purpose or result. Because it could have two meanings. Surely I think it is near to the use of purpose. but I think it is possible that At first, the two car makers combinded and then from the result, they formed one new company. So, it could be the result from combining.
which is correct?
" The beautiful weather and site combined to make the concert this year's most successful outdoor event. " As a result of the favorable weather conditions...
" Different amino acids combine to form proteins. "
In the above, they don't have will(or purpose) to form some situations, because they are not human or animals. So I understood they combined and then became the results.
Am I right? You seem to be labouring under the misapprehension that it is always the subject that performs the action named by the verb. The doer of the action is not necessarily the referent of the subject. Mediopassive verbs. Rings a bell? If the binding of the AA's happen in a controlled environment, the infinitive clause can be interpreted as a purpose. Otherwise result. Semantics, pure and simple.
So, does 'combine to infinitive' has two meanings according to the contexts where they are set? Sometimes.
If I am right, What kind of verbs are like 'combine to infinitive'?
I do not think they have a name.
If you are interested, the infinitive clauses in your sentences are sentence adjuncts of contingency.