Abstract: The panel assembly has a panel generally fitting in a hole and having an outer periphery running generally parallel to the inner periphery of the hole. Respective geometrically similar inner and outer annular frames on the inner and outer peripheries have confronting outer faces forming an annular gap around the panel between the inner and outer frames. One of the frames has an inner face forming an annular compartment extending around the respective periphery. This one frame is formed with an array of throughgoing openings extending between the respective inner and outer faces and the compartment is substantially closed except at the openings. An annular body of heat-swellable material is provided in the compartment so that on heating of the material it swells and exits the compartments through the openings to fill the gap.

Abstract: An inner frame for a cover and an outer frame for an inspection opening can be formed with frame members having flanges projecting from the plane of the frame and formed with tongues at their ends engageable by resilient hooks of the respective corner elements which fit without play against the frame members. The frame ends are cut at right angles to the longitudinal edges of the frame member in the case of the outer frame and are provided with abutting miters in the case of the inner frame.

Abstract: A corner joint between mitered jambs of a door frame, with claws provided in the miter region of the jamb ends. The claws are designed as tongues cut out of the jambs. The tongues are provided with abutment elements which engage behind the respective adjacent jambs. Further, the tongues and their abutment elements are offset relative to each other and so dimensioned that in assembled state, they engage and snugly fit between the tongues of the other jamb. The manufacture and assemblage of the frame jambs is thereby considerably simplified.

Abstract: A tool for the mitering of frame members has a lateral shoulder cooperating with a lateral guide for the punch so that a vertical bending edge of the latter deform the trim flange of a profile against a rounded portion of a cutting die on which the profile is supported to form a rounded trim edge, simultaneously with the mitering operation.

Abstract: A heat exchanger has a heat-exchange plate having an edge and formed with a lurality of parallel spaced-apart longitudinal passages opening at the edge and with a plurality of transversely throughgoing plate holes at the edge between the passages. A manifold pipe formed with a row of manifold holes all opening in the same direction and spaced apart the same as the passages at the edge can be fitted to the plate with the plate edge over the row of manifold holes so that each of the passages is aligned longitudinally with a respective one of the manifold holes. A pair of L-section guides fixed on the pipe flank the row of manifold holes and define a gap corresponding to the shape of the plate at the edge. These guides are formed between the manifold holes with laterally throughgoing guide holes transversely alignable with the plate holes when the edge is fitted over the row of manifold holes.