United States Patent 
Sznopek et al.
[ii] 4,319,950  Mar. 16, 1982
 MANDREL FOR MAKING A COUPLING FOR RIGID PRESSURE PIPE
 Inventors: John L. Sznopek; Charles Lostak;
Robert W. Heisler; Joseph P.
Ferraro; Henry J. Kazienko, all of
 Assignee: Manville Service Corporation,
 Appl. No.: 135,565
 Filed: Mar. 31,1980
Related U.S. Application Data
 Division of Ser. No. 918,226, Jun. 23, 1978.
 Int. C1.3 B29C 1/00; B29D 23/12
 U.S. CI 156/475; 156/446;
156/598; 425/469; 425/471
 Field of Search 425/460, 469, 457, 470,
425/471; 156/598, 169, 171, 172, 173, 187,414,
 References Cited
U.S. PATENT DOCUMENTS
2,744,043 5/1956 Ramberg 156/173
2,814,330 11/1957 Vanzo et al 156/414
2,837,456 6/1958 Parilla 156/173
2,848,133 8/1958 Ramberg 156/173
2,896,976 7/1959 Wiltze .
3,407,10! 1/1968 Lockshaw .
3,462,175 8/1969 Johnson 285/53
4,003,541 1/1977 Schuldink .
FOREIGN PATENT DOCUMENTS
2744739 4/1978 Fed. Rep. of Germany .
631120 12/1927 France .
Primary Examiner— Willard E. Hoag
Attorney, Agent, or Firm—Robert M. Krone; Joseph J.
Kelly; Gregory W. O'Connor
Mandrel for making a coupling which coupling comprises a body of fiber glass reinforced plastic which has a rubber sleeve embedded therein. The rubber sleeve is a one piece unit which includes specially shaped sealing gaskets on either end and has a rubber liner spanning the area between these sealing gaskets. This rubber sleeve is stretched onto a steel and plastic molding mandrel. This stretching places the rubber liner under tension which reduces the cross-sectional area of the liner and compensates for thermal expansion of the liner during curing. The mandrel/sleeve combination is rotated in order to wind a thermosetting resin impregnated fiber glass roving around the outer circumference of the mandrel/sleeve combination, thus embedding the sleeve in the fiber glass reinforced resin matrix. The thermosetting resin is cured at elevated temperatures, hardening into a rigid coupling with the embedded rubber sleeve integral therewith. Thereafter the hardened coupling is stripped from the steel and plastic mandrel and subjected to a further curing and finishing operation.
5 Claims, 4 Drawing Figures