Abstract: An angular connection for a frame or counterframe composed of hollow sections of plastic material includes at least one plastic angular element inserted with its two legs fitting firmly in the hollow sections at the point at which they converge. The walls of the sections are welded to the legs of the insert by ultrasonic spot welds. A second plastic insert may be provided for connecting together edges of the sections, the first plastic insert being arranged to connect the main bodies of the sections together. Both inserts are connected to the hollow sections by ultrasonic spot welds. A method of making an angular connection for a frame and counterframe includes the step of welding hollow sections to at least one plastic angular element using ultrasonic welding techniques.