Abstract: When a weld area of weld surface between a flange portion 3a of a pipe 3 and a flange portion 4a of a pipe connection member 4 is S and total energy consumed on the weld surface is Et, ultrasonic welding is carried out to produce said ultrasonic weld assembly in such a manner that an energy density E defined as the quotient obtained by dividing the total energy Et by the weld area S satisfies the relation 26.69e?0.3708P<E<240.9e?0.1445P with a surface pressure P on the weld surfaces of the flange portion 3a and the flange portion 4a. Preferably, ultrasonic welding is carried out in such a manner that the energy density E satisfies the relation 133.45e?0.3708P<E<240.9e?0.1445P.

Abstract: When a weld area of weld surface between a flange portion 3a of a pipe 3 and a flange portion 4a of a pipe connection member 4 is S and total energy consumed on the weld surface is Et, ultrasonic welding is carried out to produce said ultrasonic weld assembly in such a manner that an energy density E defined as the quotient obtained by dividing the total energy Et by the weld area S satisfies the relation 26.69e?0.3708P<E<240.9e?0.1445P with a surface pressure P on the weld surfaces of the flange portion 3a and the flange portion 4a. Preferably, ultrasonic welding is carried out in such a manner that the energy density E satisfies the relation 133.45e?0.3708P<E<240.9e?0.1445P.

Abstract: In a voice mail exchange for voice mail telephone sets grouped into first through N-th groups, where N represents a first predetermined number, a message recorder comprises memory sectors in one-to-one correspondence to the first through N-th groups for storage of messages originating at and destined to the telephone sets. The voice mail exchange may also include interface circuits which are selectively put in operation by control signals produced in accordance with predetermined office data by a control unit. The interface circuits interface between first through N-th recorder signals supplied to (and reproduced from) the memory sectors and first through M-th switchboard signals produced by (and supplied to) a switchboard connected to the telephone sets, where M represents a second predetermined number related to N by the office data.