There are several records that show up on FamilySearch and Ancestry related to Daniel R. Cairns (father and son).

According to the US Social Security Database, Daniel R. Cairns was born 5 September 1948 and died 29 August 2009.

Daniel Richard Cairns was born 8 Apr 1922 and died 12 Jan 1985 in Pinellas, Florida. He was born in Wisconsin, according to the US draft records, and was living in Kenosha, Wisconsin, in 1942, when he enlisted in the army at Milwaukee.

I couldn't find him in the 1930 US census, but FamilySearch gives the US Social Security Death information for both men and possibly you could order the record and find out more in that way.