A riveting method and its riveting device

Abstract

The present invention discloses a riveting method and a riveting device for connecting two parts by means of a rivet mandrel made of plastic. The riveting device includes a riveting die and a radiation source that transmits energy without contact from its rear side, and the rivet mandrel is plasticized by hot air or solidified by a coolant after being plasticized; thus, the riveting can be completed quickly without affecting the structure and color of the connecting parts.

Description

Technical Field

[0001] The present invention relates to the field of connection, and more particularly to a riveting method and a riveting device. Background Art

[0002] Connecting two parts to each other by means of a plastic rivet round nail (rivet pin or rivet pin) is a common means in the connection method. The rivet dome is molded or attached to one of the parts. The rivet dome passes through an opening in the other part, and then the rivet mandrel is usually heated to the plasticizing temperature and deformed by a rivet punch placed on the rivet mandrel so that the deformed rivet mandrel engages on the other part. After the cooling stage, in which the rivet mandrel is cooled to its solidification temperature, the rivet mandrel is then lifted from the rivet dome, so that the two parts are firmly connected to each other by the rivet dome.

[0003] At the same time, there are various existing methods for heating the rivet mandrel. Usually, the rivet dome is brought to its plasticizing temperature by an electric heating element, by blowing in hot air or by ultrasound; in addition, it is in principle known to use infrared rays to heat the rivet mandrel.

[0004] The disadvantages of these known methods are that, due to the relatively long heating and cooling times, they generally do not allow the short cycle times desired in automated operation. Another disadvantage is that when heating the rivet dome, the areas of the parts to be joined around the rivet dome are usually heated in such a way that damage occurs in these areas in the form of undesired changes in the color and structure of these parts; this is usually unacceptable, especially when the color and structure changes are on the visible side of the part. Summary of the Invention

[0005] Therefore, in order to solve the above deficiencies, the present invention provides herein a riveting method and a riveting device for connecting two or more parts by means of a plastic rivet mandrel. With this riveting method and riveting device, the parts can be quickly connected and effectively riveted without damaging the parts.

[0006] The riveting method disclosed by the present invention is used to connect two components by means of a plastic rivet mandrel. The rivet mandrel is deformed by a riveting die, which is heated from its rear side without contact to a plasticizing temperature suitable for plasticizing the rivet mandrel by thermal radiation or by applying hot air, and the rivet mandrel is plasticized by contacting the heated riveting die; by non-direct-contact heating, the heating time is shortened and the heating efficiency is improved. The heated riveting die transfers heat to the rivet mandrel in a targeted manner without causing significant heat loss, so the cycle time can be reduced. In addition, damage to the surrounding heat-related areas, especially changes in color and structure, can be prevented. Since the riveting die has no mechanical connection with the heat source, the riveting die can be more easily replaced as needed.

[0007] Preferably, the riveting die is heated by infrared radiation. Other radiation sources for heating the riveting die can be conceived in principle, such as a wide variety of laser radiations. If the riveting die is heated by hot gas, the hot gas preferably consists of hot air.

[0008] Preferably, after the deformation of the rivet mandrel, the riveting die is cooled by a gaseous coolant, and the gaseous coolant is directed to the back of the riveting die. Cold air is preferably used as the gaseous coolant. The deformed rivet mandrel is also preferably cooled specifically or mainly by the riveting die, which enables rapid heat transfer and short cooling times.

[0009] The riveting device as indicated in the riveting method, which has a heat radiation source for non-contact heating of the riveting die by thermal radiation. In this case, the heat radiation source is arranged behind the rivet die. The thermal radiation is preferably directed directly at the riveting die, and the thermal radiation is preferably an infrared radiation source. The riveting device is used to connect two components by a plastic rivet mandrel. The riveting device has a riveting die capable of contacting the rivet mandrel to deform the rivet mandrel, and further includes a heat source that non-contact heats the riveting die and is located behind the riveting die.

[0010] Preferably, the heat source is a heat radiation source for non-contact heating of the riveting die by thermal radiation, where the heat radiation source is behind the riveting die.

[0011] Preferably, the heat radiation source is an infrared radiation source.

[0012] Preferably, the heat source is a hot gas source having at least one hot gas outlet, and the hot gas outlet is arranged behind the riveting die such that the hot gas is guided to the back of the riveting die.

[0013] Preferably, the riveting device further includes a cooling device that works together with a gaseous coolant and has at least one coolant pipeline. The coolant pipeline has a coolant outlet towards the riveting die, and the coolant is directed to the riveting die. The temperature of the rivet die is reached by the coolant to a temperature at which the rivet mandrel solidifies. This setting can enable the riveting die to reach a temperature at which the top of the rivet mandrel solidifies by the coolant. One or more such coolant pipelines are provided, which guide the coolant to the rivet die from different sides or the center to achieve better cooling effect.

[0014] Preferably, the riveting die is cup-shaped and includes an end wall and a sleeve-shaped peripheral wall; the end wall has a forming surface matching the rivet mandrel. The sleeve-shaped peripheral wall has the effect that hot gas and / or gaseous coolant are concentrated at the rear side of the end wall of the riveting die, whereby rapid and effective heating and cooling of the rivet mandrel can be carried out and it can be withdrawn in a timely manner.

[0015] Preferably, the peripheral wall is connected to the end wall only by webs, and free spaces are arranged between the webs, and the free spaces extend over a major part of the circumference of the peripheral wall. These free spaces allow the air heated by thermal radiation or hot gas and gaseous coolant to be easily discharged from the interior of the riveting device and from the rear of the riveting punch to the outside.

[0016] Preferably, a riveting die holding device is further included, and the riveting die holding device has a receiving sleeve, and the riveting die is installed in the end region of the receiving sleeve; the heat radiation source is arranged in the receiving sleeve, or the hot air outlet of the hot gas source is aligned with the riveting die, so that heat radiation or hot gas is led to the end wall of the riveting die from the rear. This setting enables the manufacture of a very compact, efficient and fast-working riveting device.

[0017] Preferably, the coolant outlet is arranged inside or above the receiving sleeve, and particularly near the riveting die. Particularly preferably here, the coolant pipeline leads to the receiving sleeve near the riveting die or is located in the center of the receiving sleeve, which establishes a short and direct path for the cooling air or another cooling gas in the receiving sleeve from the coolant outlet to the end wall of the rivet die, which also contributes to the rapid and effective cooling of the rivet die.

[0018] Preferably, the riveting die is made of a metal with a high thermal conductivity, and the riveting die is preferably made of a metal with a high thermal conductivity, especially steel or brass. In this way, particularly short heating and cooling times of the rivet die can be achieved.

[0019] Preferably, the back surface of the riveting die has a matte or dark color to accelerate heat absorption.

[0020] Preferably, the end wall of the riveting die is thin-walled, and this setting is beneficial to shortening the heating and cooling times.

[0021] The present invention has the following advantages:

[0022] The present invention is ingeniously conceived, can quickly complete the connection of two components through plastic parts, adopts non-contact energy transfer, has a fast response, a short heating or cooling cycle, a good connection effect, and does not affect the structure, shape and color of the two connecting parts. Description of the Drawings

[0023] Figure 1 is a three-dimensional view of the riveting device of the present invention;

[0024] Figure 2 is Figure 1 a partial schematic longitudinal sectional view of the lower part of the riveting device, and a rivet mandrel arranged below the riveting device;

[0025] Figure 3 is an exemplary riveting die inclined from below;

[0026] Figure 4 is Figure 3 the angle at which the rivet die of

[0027] Figure 5 is a longitudinal section passing through the riveting die, and this section is in the plane of the web;

[0028] Figure 6 : a longitudinal section passing through the riveting die, and this section is in the plane between the webs;

[0029] Figure 7 is a schematic diagram of the working state process of the present invention, in which 7a to 7c show different stages of manufacturing a rivet connection. Detailed implementation mode

[0030] The following will combine the attached Figures 1-7 to describe the present invention in detail, and clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0031] As Figure 1 shown, there is a riveting device 1, which has a guide sleeve 2 and a holding element 3 that fixes the guide sleeve 2. With the help of the holding element 3, the riveting device 1 can move at least in its longitudinal direction, that is, move axially; with the help of a moving mechanism not shown, in the embodiment shown in the vertical direction becomes.

[0032] In the shown embodiment, the guide sleeve 2 is arranged vertically, and the holding element 3 extends horizontally in the form of a transverse arm. The guide sleeve 2 is attached to one end of the transverse arm by a fixture, for example. Other types and selections of the guide sleeve 2 and the holding element 3 are easy.

[0033] By moving the riveting device 1 longitudinally, the riveting device 1 can be placed on the rivet mandrel 4 ( Figure 2 ) and lifted upward from it.

[0034] The guide sleeve 2 extends at its upper end (rear or posterior) by means of an elongate polygonal element 5 which serves to adjust the angle of the riveting device 1.

[0035] Furthermore, it can be seen from Figure 1 that the riveting device 1 comprises a connection module 6 having a retaining plate 7 to which are attached electrical plug connectors 8 for a temperature sensor and for a heat radiation source 19, which plug connectors 8 are shown schematically, Figure 2 the heat radiation source 19 in the illustrated embodiment being an infrared radiation source.

[0036] From Figure 2 it can be seen that a tubular retaining rod 9 is arranged in the guide sleeve 2 so as to be longitudinally displaceable, the retaining rod 9 extending downwardly beyond the lower end 10 of the guide sleeve 2.

[0037] A fixing seat 11 is fixed to the lower end of the tubular retaining rod 9, for example by means of a thread 12. The outer diameter of the fixing seat 11 is greater than the outer diameter of the retaining rod 9 such that the end face 13 of the fixing seat 11 forms a diameter step relative to the retaining rod 9.

[0038] A compression spring 14 surrounding the retaining rod 9 is arranged between the fixing seat 11 and the lower end 10 of the guide sleeve 2. The lower end of the compression spring 14 bears on the end face 13 of the fixing seat 11 or on an intermediate disc on this fixing seat, and its upper end bears on the lower end face 15 of the guide sleeve 2. Due to this arrangement, when the force of the riveting device 1 on the rivet mandrel 4 exceeds the counterforce, the fixing seat 11 and the retaining rod 9 can move upward relative to the guide sleeve 2 against the force of the compression spring 14 being compressed.

[0039] A receiving sleeve 17 extending longitudinally downward along the retaining rod 9 is preferably fixed to the fixing seat 11 by means of a thread 16. The heat radiation source 19 is arranged inside the receiving sleeve 17;

[0040] The heat radiation source 19 is connected to a power supply line which is routed upward inside the retaining rod 9, reaches the relevant plug connector 8 via the polygonal element 5 and is connected to the corresponding power supply. Preferably, the heat radiation source 19 generates infrared rays which are radiated from a lower radiation surface 21 onto the riveting die 22 in order to quickly heat it to a temperature suitable for plasticizing the rivet mandrel 4.

[0041] Instead of the heat radiation source 19, a hot gas source can also be used to heat the riveting die 22 to a temperature suitable for plasticizing the rivet mandrel 4 by means of hot gas, especially hot air. The hot gas can be guided to the riveting die 22 centrally, for example, through the holding rod 9 or through an external hot gas pipeline. In the case where the riveting die 22 is heated by hot gas, the riveting device can have a hot gas supply element 18 with a hot gas outlet 20 instead of the heat radiation source 19 arranged behind or on the riveting die 22. The hot gas is guided to the rear side of the riveting die 22 in such a way that:

[0042] The riveting die 22 is attached to the lower end of the receiving sleeve 17, for example, by a thread 23. The riveting die 22, the receiving sleeve 17, the fixing base 11, and the holding rod 9 thus form a rigid unit that extends in its longitudinal direction relative to the guide sleeve 2 against the compressive force of the compression spring 14.

[0043] In the above embodiment, the riveting die 22 includes an end wall 24 and a sleeve-shaped peripheral wall 25 that is screwed into the lower end region of the receiving sleeve 17, and another connection, such as a welded connection, can be easily made. In addition, it is also conceivable to integrally construct the receiving sleeve 17 and the riveting die 22, where the general shape of the riveting die 22 is cup-shaped.

[0044] As can be seen especially from Figures 3-6 the peripheral wall 25 of the rivet punch 22 has a radially outwardly protruding collar 26 that serves as an axial stop for the rivet punch 22 when the rivet punch 22 is screwed into the receiving sleeve 17 to strike the lower end wall 27 of the receiving sleeve 17 ( Figure 2 ).

[0045] The end wall 24 of the rivet punch 22 is arranged at a certain distance below the peripheral wall 25 and is connected to it by four webs 28; there is a free space 29 between the peripheral wall 25 and the end wall 24 that extends circumferentially between the webs 28. The hot air used to heat the riveting die 22 or the hot air generated when dissipating heat from the riveting die 22 and the cold air used to cool the rivet punch 22 can be discharged through these free spaces 29.

[0046] At one end facing the rivet mandrel 4, the end wall 24 has a forming surface 30 that can be placed on the rivet mandrel 4, and the forming surface is designed according to the shape that the rivet mandrel 4 will have after its deformation process. In the shown embodiment, the forming surface 30 is formed by a circular recess 31 around the central pin 32 of the end wall 24. The diameter of the pin 32 is such that the pin 32 can be inserted into the interior of the sleeve.

[0047] The end wall 24 of the riveting die 22 is preferably and in particular in the region of the forming surface 30, in the region of the circular recess 31, the wall is thin-walled and has a high thermal conductivity, so that the end wall 24 can be heated and cooled quickly. The thickness of the end wall 24 in the apex region of the forming surface 30 is preferably only 1-10% of the diameter of the end wall 24, especially 1-5%. The riveting die 22 is preferably made of the following materials: metals with high thermal conductivity, especially steel or brass.

[0048] The riveting die 22 and the deformed rivet mandrel 4 are cooled by a cooling device 33, which in the exemplary embodiment shown includes two coolant lines 34; the coolant lines 34 can be connected via a connector 35 to additional coolant supply lines (not shown). Gaseous coolant, especially cold air, can be supplied to the riveting die 22 through the coolant lines 34.

[0049] In the embodiment shown, the coolant lines 34 extend radially opposite along the guide sleeve 2 and the receiving sleeve 17, and extend radially, and open directly above the riveting die 22 via a coolant outlet 39 into the interior of the receiving sleeve 17. Along the direction of the riveting die 22, it is preferably directed directly towards the end wall 24. As an alternative to this, the gaseous coolant can also be guided to the riveting die 22 in some other way, for example through the interior of the holding rod 9 from the center.

[0050] The following refers to Figure 7 Figures 7a to 7c for a more detailed description of the riveting method according to the present invention;

[0051] Figure 7 Figure a shows a longitudinal sectional view of the lower part of the riveting device 1, and the riveting die 22 of the riveting device is initially arranged at a small distance above and aligned with the rivet mandrel 4.

[0052] The rivet mandrel 4 made of plastic is molded onto the first part 36 and extends through the opening 37 of the second part 38, and the second part 38 is placed on the first part 36 and is intended to be connected to the first part 36. In addition, the rivet mandrel 4 is designed in a sleeve shape and protrudes upward by a predetermined amount beyond the second part 38.

[0053] In this state, the heat radiation source 19 is activated and heat is radiated onto the back surface of the riveting die 22, that is, on the back surface of the riveting die 22, especially on its end wall 24, so that the forming surface 30 reaches the plasticizing temperature of the rivet mandrel, which is suitable for softening the rivet mandrel 4; the temperature of the riveting die 22 is monitored by a temperature sensor (not shown in detail).

[0054] Then, from Figure 7It can be seen that the riveting device 1 is lowered and placed on the rivet mandrel 4. The portion of the rivet mandrel 4 protruding beyond the second part 38 is plasticized by heat transfer through the overlapping of the riveting die 22.

[0055] In Figure 7 b, the riveting device 1 is shown in its lowest position, where the riveting die 22 rests on the second part 38 and the rivet dome head 40 is fully formed. In this state, the heat radiation source 19 is turned off and the cooling device 33 is activated so as to guide a gaseous coolant, in particular cooling air, via the coolant line 34 to the back of the riveting die 22, especially at its end wall 24. Finally, the riveting die 22 is cooled to the solidification temperature of the rivet dome until the deformed rivet mandrel 4 reaches the solidification temperature; the rivet mandrel 4 is cooled by heat transfer from the riveting die 22 to the rivet mandrel 4.

[0056] In Figure 7 As shown in c, the riveting device 1 is lifted and disengaged from the plasticized rivet mandrel. After the rivet mandrel 4 solidifies, the supply of the gaseous coolant through the coolant line 34 is blocked and the riveting device 1 is lifted from the rivet mandrel 4; at this time, the heat radiation source 19 can be activated again to reheat the riveting punch 22 in order to start a further riveting process.

[0057] The foregoing description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Thus, the invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A riveting method for connecting two components (36, 38) by means of a rivet mandrel (4) made of plastic, the rivet mandrel (4) being deformed by a riveting die (22), characterized in that, The riveting die (22) is heated to a plasticizing temperature suitable for plasticizing the rivet mandrel (4) without contact from its rear side, either by thermal radiation or by applying hot gas, and the rivet mandrel (4) is plasticized by contact with the heated riveting die (22); The riveting die is cup-shaped, including an end wall and a sleeve-shaped peripheral wall. The peripheral wall of the riveting die has a radially outwardly protruding collar. The end wall of the riveting die is arranged at a certain distance below the peripheral wall and is connected to it by four webs; there is a free space between the peripheral wall and the end wall, and this free space extends circumferentially between the webs.

2. The riveting method according to claim 1, wherein: The riveting die (22) is heated by infrared radiation.

3. The riveting method according to claim 1 or 2, characterized in that: After the rivet mandrel (4) is deformed, the riveting die (22) is cooled by a gas coolant, and the gas coolant is directed to the back side of the riveting die (22).

4. A riveting device for connecting two components (36, 38) by means of a rivet mandrel (4) made of plastic, the riveting device having a riveting die (22) capable of contacting the rivet mandrel (4) to deform the rivet mandrel (4), characterized in that: It also includes a heat source that heats the riveting die (22) non-contact and is located behind the riveting die (22); The riveting die is cup-shaped, including an end wall and a sleeve-shaped peripheral wall. The peripheral wall of the riveting die has a radially outwardly protruding collar. The end wall of the riveting die is arranged at a certain distance below the peripheral wall and is connected to it by four webs; there is a free space between the peripheral wall and the end wall, and this free space extends circumferentially between the webs.

5. The riveting device according to claim 4, wherein: The heat source is a thermal radiation source (19) that non-contact heats the riveting die (22) by thermal radiation, and the thermal radiation source (19) is behind the riveting die (22).

6. The riveting device according to claim 5, characterized in that: The thermal radiation source (19) is an infrared radiation source.

7. The riveting device according to claim 4, wherein: The heat source is a hot gas source that has at least one hot gas outlet, and the hot gas outlet is arranged behind the riveting die (22) so that the hot gas is guided to the back side of the riveting die (22).

8. The riveting device according to any one of claims 4-7, characterized in that: The riveting device also includes a cooling device (33) that works together with a gaseous coolant and has at least one coolant line (34). The coolant line has a coolant outlet (39) towards the riveting die (22), and the coolant is directed to the riveting die (22) to bring the temperature of the riveting die (22) to a temperature at which the rivet mandrel (4) solidifies.

9. The riveting device according to claim 8, characterized in that: The riveting die (22) is cup-shaped and includes an end wall (24) and a sleeve-shaped peripheral wall (25); the end wall (24) has a forming surface (30) matching the rivet mandrel (4).

10. The riveting device according to claim 9, characterized in that: The peripheral wall (25) is connected to the end wall (24) only by webs (28), and a free space is arranged between the webs, and this free space extends over a major part of the circumference of the peripheral wall.

11. The riveting device according to claim 9 or 10, characterized in that: It also includes a riveting die holding device that has a receiving sleeve (17), and the riveting die (22) is installed in the end region of the receiving sleeve; the thermal radiation source (19) is arranged inside the receiving sleeve (17), or the hot air outlet of the hot gas source is aligned with the riveting die (22) so that thermal radiation or hot gas is led to the end wall (24) of the riveting die (22) from the rear.

12. The riveting device according to claim 11, characterized in that: The coolant outlet (39) is arranged inside or above the receiving sleeve (17).

13. The riveting device according to claim 12, characterized in that: The riveting die (22) is made of a metal with a high thermal conductivity.

14. The riveting device according to claim 13, characterized in that: The riveting die (22) has a matte or dark-colored back surface to accelerate heat absorption.

15. The riveting device according to claim 14, characterized in that: The end wall (24) of the riveting die (22) is a thin wall.

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