DE2024153A1 - High-frequency pressure bonding plastics - Google Patents

Abstract

Method for joining plastic components by means of high frequency and pressure consists of joining the components and holding them together. One end of the plastic insert is placed in contact with the vibrating piston. The frequency causes melting of the material and the pressure causes formation of a sealing flange in the hole. The piston vibration movement is stopped but the pressure is maintained until the material has cooled and hardened and components are anchored. The openings in the mounting plate can be of any shape. For forming electrical connecting elements by joining components made from electrically insulating plastics on mounting plates. Also for joining electrical plastic connectors to metal coated plates at a high production rate. The method is suitable for attaching components which can be readily detached without damage.

Description

Method for fastening related parts by means of high-frequency Vibrations and Pressure The present invention relates to a method of making related To fasten parts together, one of the parts by applying high frequency vibrations and pressure is deformed or plugged in during assembly. Although the procedure offers general application possibilities, it can be used particularly advantageously when assembling electrical pre-binding elements consisting of an insulating Made of plastic material, with a recessed carrier plate, which usually, from meta ;; bslteht, minted and carried by this W @@@ len, Electric Connections for electrical or electronic parts are mostly made by connecting elements made, which consist of an insulating plastic and on a carrier plate are mounted. The connecting elements are designed so that they are removable Fasteners - can accept electrical connections from others Share wear. In particular with complex electrical systems, space is required save or to achieve a reduction in size, so far a large number of connection sockets mounted on a single carrier plate, which is provided with recesses, to pick up and carry the individual connecting elements.

During assembly it is necessary to use the connecting elements to be attached to the perforated plate around the individual connecting elements take up and carry. Be fasteners must be strong enough to be without To withstand the forces involved in inserting and withdrawing the associated connector occur. Previous attempts to find a simple and fast method of attaching connector sockets to a carrier plate Finding one that has satisfactory strength does not have to be full Success led. Tried the connection socket in the associated recesses the carrier plate with a PreßjCitz to use a holder by friction to achieve, have led to the deformation of the carrier plate, since its strength is reduced by the recesses. Gluing in the fasteners is time consuming and the breakage of the adhesive bond is common, mechanical deformation or assembly of parts with a hammer blow, as is often the case with fastening Metal parts that belong together cannot be used because the plastic The fasteners would break if the impact occurred, a deformation of the plastic on the inside of the pint, e.g.

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Such a process is time consuming because of the plastic the amount of heat flowing away is relatively low.

It is therefore an object of the present invention to provide an improved one Finding a method of securing related parts, one of which, at least partially, consists of a plastic.

Another object of the invention is to provide an improved method for fastening plastic electrical connection elements on a perforated Provide metal support plate that is labor saving and high speed Can be mass produced and with high strength the connection is achieved to withstand the forces exerted upon onset and pulling out plug connections occur.

Other objects and advantages of the invention will appear from the following Description clear.

According to the invention, related parts, of which at least one is partially made of plastic, assembled and fastened together through an improved method, the high frequency (ultrasonic) vibrations and pressure applies.

One of the parts that belong together, e.g. a base of an electrical Forming connecting element is made of an insulating plastic. He has a protruding portion of reduced cross-section so formed is that it extends through a bore in the other associated part, which e.g. the perforated carrier plate.

In the assembled position, a pressure body or piston is used brought to the edges of the protruding part, which extends through the carrier plate extend through and beyond them. The piston is caused to do so with vibrate at a high frequency and amplitude, so high that it is sufficient to around the plastic in a limited area that corresponds to the piston in Touch stands to heat up and soften quickly. A certain pressure that Continuously exerted by the piston causes the plastic to go down and to flow outwards over the carrier plate through or out, at least around part of the circumference of the bore, forming a mounting flange will. The vibratory movement of the piston is then stopped while the piston pressure is applied is maintained on the softened plastic over a dwell time the molded flange cools and hardens, whereby the parts that belong together be firmly connected to each other. The length of time during which the vibration energy applied to the piston is controlled so that an excessive Heating and melting of the plastic is prevented, with the loss of strength could occur. The entire fastening process- can either be done by hand or be carried out with the help of automatic or semi-automatic machines, in a few seconds. The strength of the mounting flange can be through Bevelling of the edge of the hole in the support plate can be increased, thereby reducing the molded mounting flange has a wedge shape which increases resistance offers against the attacking tensile forces.

For a better understanding of the invention, refer to the following Description of details referred to in conjunction with the attached Drawings.

Fig. 1 is a perspective view of a carrier plate> the is perforated and mounted and fastened on the connection base according to the invention Fig. 2 shows a side view of a connecting hook partially in the section that is made in the carrier plate before the operation begins. One embodiment of a plug which is designed so that it in the connection socket is shown in dashed lines to indicate the direction indicate the tensile forces that occur when the connector is separated from the socket will.

Fig. 3 shows a front view of the connecting element in section, as it is arranged on an assembly jig and a vibrating piston, as it rests against the fastener at the start of the fastening process.

Fig. 4 is similar to Fig. 3, only that the piston is in a subsequent position which is intended to show how a retaining flange is attached to the connecting element is molded by vibration and pressure.

Fig. 5 shows a side view of an ultrasonic press, in part shown schematically, as well as an associated control device, which in the fastening process is applied.

6 shows structural details in a perspective view of the vibrating piston, as it is in the press according to FIG. 5 for fastening the connecting elements is used on the carrier plate.

To an application example of the fastening method according to the invention To explain, a carrier plate 10 is shown in Fig. 1, which has a number of has right-angled breakthroughs or bores 11, which have a number of electrical, accommodates rectangular sockets, such as .B. the connecting element shown in FIG 12. The connecting element 12 has a lower part 13, which with shoulders 14 and 15 is provided and rests on one side of the carrier plate 10. The connecting element 12 also has a projection 16 with a reduced rectangular cross-section, who was held so that it is in one of the holes 11 of the plate 10 fits in and extends through it. The connecting element 12, which consists of an insulating plastic, carries at a distance from each other a number of connector pins 17, on which in a typical manner, for example by soldering or by means of wrapping, connecting wires are attached. A recess 18 am The lower part of the connecting element 12 is designed so that it has a matching Can accommodate connector 19, which is shown in dashed lines. This plug 19 has contact strips 20 which rest on spring fingers 21 and make electrical contact when the plug is inserted.

The fastening method according to the present invention can be found in are carried out in the manner described below, the approach 16 of the Connecting element 12 after installation in one of the bores 11 of the plate 10 is deformed, so that a mounting flange 22 (Fig. 4) is formed, which is against the plate 10 is supported on the side opposite the shoulders 14 and 15. The fastening flange 22 must be sufficiently strong to hold the connection base 12 hold tightly in the assembled position and withstand forces like them attack when the associated plug 19 is repeatedly pulled out on the connection base. As can be seen from Fig. 2, when the connector is inserted, the forces acting on the connecting element 12 from the shoulders 14 and 15, which rest on the opposite side of the plate 10, resistance opposite.

To fasten the connecting element 12 on the plate 10, is first the connecting element on an assembly jig 23, as shown in FIG is attached. The assembly jig 23 is attached to the carrier 24 by means of bolts 25 fixedly attached and has an upwardly directed, wedge-shaped straightening rod 26 on, which is in a recess 18 between the Contact springs 21 pushes, these being pushed outwards' and by the stops 26a in one Be pushed away, as it happens similar to the plug 19.

The end pieces 27 on each side of the lug 16 extend into matching end recesses in the connecting element, so that the connecting element is held firmly in place and through the assembly jig 23 with the Approach 16 is brought up into a horizontal position. The plate 10 is then placed over the connecting element so that it rests on the shoulders 14 and 15 and the projection 16 extends into the plate 10 through one of the recesses 51.

The mounting flange 22 is at the upper end of the extension 16 of a vertically movable piston 28 is formed. The piston 28 is actuated by a conventional press, so that a continuous and controlled, downward directed pressure is exerted on the approach 16. The lower working end of the piston is provided with a right-angled recess 29 to allow a margin for the To provide connector pins 17 and to form the lower work surfaces 30 and 31, which are dimensioned so that they are at the opposite edges 32 and 33 of the approach 16 rest.

The piston is then moved down to the position of FIG. 3, in which the work surfaces 30 and 31 rest against the edges 32 and 33 of the projection 16 and attack them. At the same time, the piston is replaced by a conventional one Energy converter set in vertical vibrations, and with a sufficient Frequency and length to the plastic in the contact area with the piston to warm and soften.

The scanning frequency is preferably above the audible range, i.e. 20 kHz to avoid any nuisance to the user. A continued downward Directional pressure of the piston pushes the soft plastic material down and down outside so as to form the mounting flange 22, which the plate 10 protrudes on the opposite side of the carrying shoulders 14 and 15. The area of the approach 16, which is softened by the ultrasonic vibration energy, is shown in FIG 4 highlighted by shades 34 and 35. After the flange 22 is formed the piston stops vibrating and the piston pressure is maintained until the softened plastic material cools and hardens, around the connector 12 and the plate 10 to be firmly connected. The plunger is then withdrawn and the plate assembled with the connecting element from the assembly jig 23 lifted off and the fastening process ended.

The rod 26 prevents vibrations by following the spring fingers 21 pushes outside and this thus from the stops 26a during the fastening process keeps away, thereby avoiding that the pins 17 are heated and from the Plastic connector in which they were embedded, removed again will.

For the application shown, if desired, one Form flange of high strength and resistance to withdrawal the edges of the bores 11 are preferably wedge-shaped, as shown in FIGS. 3 and 4 shown. This results in a shape of the flanges 22 with wedge-shaped Parts 36 and 37, through which practically radial pressures are absorbed when at forces occur when pulling out, which in turn avoids bending stresses, which can cause the flange 22 to break. To achieve the best results to achieve, one makes the oscillation period of the piston (ultrasonic time) and the continuous piston pressure (dwell time) depending on various factors, such as the workpiece shape and material, the ultrasonic energy and frequency, as well as the piston pressure, good results were achieved with a connection base, which was molded from glass fiber reinforced nylon (20 to 30 S 0 las filling) and one Ultrasonic generator with an output power of 650 watts, a working frequency of approx 20 kHz and a piston pressure greater than 1.7 kg / cm2 (25 psi). This was an ultrasonic time of 1 second and a dwell time of 2 seconds is applied, giving a total attachment time results in just 3 seconds. It can be seen that the fastening method according to the invention is fast and well suited to be used in mass production.

While performing the above procedure with a hand tool Better results can be obtained using automatic or uses semi-automatic machines that are designed to precisely perform the Control ultrasound time, dwell time and piston pressure. An ultrasonic press, how it is suitable to carry out the fastening method according to the invention, is shown in Fig. 4, to which reference is made below.

Fig. 5 shows an ultrasonic press, as it is suitable a vertical one Movement, as well as vibration and pressure of the piston 28 to control, related to the was previously referred to with the fastening method. As shown, the press contains a base 38 5 on which the carrier or the clamping device 24 and the assembly jig 23 is mounted. A column 39 extends from the base 38 from upwards and carries an adjustable head 40, + which extends radially from the Column extends so that it protrudes beyond the assembly jig 23. From the head 40 protrudes down a rod 41 carrying a transducer unit 42 in which the the Vibration-generating transducers 43 are included. is. How the converter works is known. It is e.g. from the US.

U.S. Patent 3,184,353 to Balamuth et al, referred to because of the Detailed Description Reference is made to the transducer 43 has a magnetostrictive Rod (not shown)> which is excited by a vibrator 44 to vertical To generate vibrations of the shaft 45. At the wave is with a screw connection 46, the vibration tool or piston 28 is attached. The heat produced by the transducer element is from a cooling liquid that flows through the unit through the inlet and Outlet connecting lines 47 and 48. A spool 49 is mounted on piston 28. It produces a feedback signal for the vibration generator to control the electromechanical To keep the oscillation system in a resonance oscillation when the transducer is energized will.

Preferably the ultrasonic press is with automatic control means provided to raise and lower the piston 28, a preset Piston pressure is maintained for the duration of the action of the piston. It also increases the ultrasonic time and residence time during the fastening process controlled. Such control units are commercially available, e.g. by the company Cavitron Ultrasonics, Ind., Long Island City, N.Y. The controls are schematic shown and contain a control unit 50 with a switch 51> a Transmitter for the ultrasonic time 52a and a transmitter for the dwell time 52b. In the head 40 an electrically controlled servo motor 53 is housed, the converter and raises and lowers the tool unit and a predetermined tool pressure on the workpiece during the ultrasonic mounting process.

The piston 28 is specially designed for the attachment or The insertion process as previously described. Details of this Construction are from Fig. 6 ersichta Lich. The piston is made from a piece of metal preferably made of a metal which has a high weight ratio too strong, such as titanium. As pictured, it contains a massive one flattened lower part 54 from which a cylindrical neck part 55 extends and a working portion 56 of smaller cross-section, which is an im essential has a rectangular shape. As shown, the working section is marked with a rectangular recess or opening 29, which the working surfaces 30 and 31 forms. The piston is designed so that the maximum amplitude of the vibration is reached in the perpendicular to the working surface 56 of the piston. Form the recess 29 is determined by the shape of the plastic parts on which a Flange is formed. It is possible to make the construction so that a Flange only on opposite sides of the holes through which the approach extends extends from plastic, is molded or leads around the bore.

The method according to the present invention is carried out with a press performed as shown in Fig. 5, the user gives the connecting element 12 on the assembly jig 23 and the plate 10 on the connection base 12, such as shown in Fig. 3. The control switch 51 is then closed and starts the downward movement of rod 41 and associated transducer and tool unit. Just before the point in time at which the piston 28 reaches the shoulder 16, a Limit switch 57 actuated by the movement of the rod 41 and thereby closes the Circuit of the vibration generator 44 and the transducer 42 to the vibration of the Start piston. At the same time, the transducer for the ultrasonic time is also used 52a started. The servomotor 53 stops during the entire fastening process maintains a constant, previously set piston pressure. At the end of a pre-selected Time sufficient for the plastic to soften but not melt to reach in the contact zone with the working surfaces 30 and 31 of the piston, switches the transducer for the ultrasonic time off the transducer 43 and at the same time the Trigger 52b for the dwell time. At the end of a preselected time that is sufficient to cool and harden the flange 22, the dwell timer 52b sets the upward movement of the piston 28 in motion, which returns to its starting position, by the cycle to complete.

The parts fastened together, namely the plate 10 and the connection base 12 are then removed from the assembly aulehre 23 and the process with a another connection socket in a different hole in the carrier plate like the one. If desired, the process can be completely automated by using known Applies machine tool control techniques.

The attachment method of the present invention is particular then advantageous when exact alignment of the connecting elements or other parts on the recessed carrier plate is required. In an automatic Assembly process in which connecting elements are placed in recesses in the carrier plate are used by machines, the recesses must of course something be larger than the approaches of the connecting elements through the recesses protrude through to avoid pinching them during insertion or eat. Because of the resulting play seat between the associated Divide the connector must be aligned so that the connector pins align exactly, even with automatic devices that are used to make the electrical connection with the pins. After that Fastening element is perfectly aligned, the flange is in the above mentioned process. As the flowing plastic shapes the flange, it fills he every gap between the connecting element and the carrier plate.

After the plastic has hardened, the connecting element is firmly anchored in the correct position.

Although the fastening method described is also suitable, to use round approaches of plastic parts in corresponding parts that have a have a round recess, a non-round shape is preferred to provide a resistance to provide against relative rotational movement between the parts.

Although here is a presently preferred embodiment of the invention has been described and illustrated, it will be understood that numerous skilled artisans Be able to make changes without departing from the scope of the invention, e.g.

in the form of the parts to be joined or in the attachment to Realization of this invention,

Claims (4)

Patent claims method for fastening related parts, one of which consists of a body, the one with at least one continuous Recess is provided and wherein the other part has a base body which is designed so that it is adjacent to one side of this body and with an approach of reduced cross-section molded from plastic and its outer end extends over the other side of this body in the assembled state extends out and through the recess, d a -d u r c h g e k e n n z e i c h e t that a) the parts that belong together are put together and in the put together Be held in position, b) the outer end of the extension (16) with a piston (28) is brought into contact, which exerts a continuous force on them and vibrations generated in this piston (28) parallel to the direction of this force be that have such a frequency and amplitude that the plastic in the contact zone (30, 31) with the piston (28) is heated and softened, wherein the piston forces deflect and push the softened plastic material outwards, so that a fastening flange (22) on the extension (16) is formed, which is at least partially supported on the circumference of the recess (1), c) the oscillatory movement of the piston (28) is stopped while the piston pressure is applied to the softened plastic material continues until the flange (22) cools and hardens, with the parts (10, 12) interlocking and d) the piston (28) is withdrawn. 2. The method according to claim 1, g e k e n n z e i c h n e t d u r c h such a design of the part (10) that indicates the recess (in) a beveled edge runs around the circumference of this recess, wherein the fastening flange (22) has a wedge shape (36, 37), so that an additional Resistance to the separation of the parts arises. 3. The method according to claim 1, d a d u r c h g e k e n n -z e i c h n e t that the recess (11) in one part (10) and the extension (16) of the associated Part (12), which extends through the recess (11), have a non-round shape, to prevent relative rotational movement between the parts (16, 10). 4. The method of claim 1, d a d u r c h g e k e n n -z e -i c h n e t that the part with the recess (11) is designed as a carrier plate (10) is and the other part, which consists of a base part (12) and one through this There is recess (11) extending approach (16) as an electrical connecting element is formed and is mounted and fastened on this plate (10; the Connecting element electrical connecting means extending through the approach (16) through and into the recess within the contact surface (30, 31) of the Piston (28) in which the mounting flange (22) is formed extend.