DE102004015568A1 - Combined clinching and punch riveting tool for mechanical joining of at least two workpieces has punch lifting device through which punch lift is selectively adjustable between lift for clinching and lift for punch riveting - Google Patents

Abstract

The combined clinching and punch riveting tool for the mechanical joining of at least two workpieces comprises a frame (2), a multi-section bottom die (12) to support the workpieces, a punch (8) for carrying out the joining process, a drive for the punch, a holding down device (10) for pressing of the workpieces onto the bottom die during the joining process, a device for feeding punching rivets of a defined geometry into a channel in the punch, and a punch lifting device (30,32) through which the punch lift is selectively adjustable between a lift for the clinching and a lift for the punch riveting.

Description

The The invention relates to a combined push-through punch riveting tool for mechanical Add at least two workpieces optionally by means of clinching, also called clinching, or by means of punch rivets.

in the The prior art are similarly constructed for clinching and punch riveting Tools used, however, in their stamp and Matrizengeometrien as well as in other important design details. So is to set semi-hollow punch rivets usually one Die used with a circular die recess in the Middle is raised to the necessary spreading of the punch rivet to ensure. A typical push through matrix on the other hand has a flat bottom and several radially outwardly movable Die segments on which yield when forming the closing head to the outside. Furthermore, as a rule, different stamp geometries and hold down systems used. Because of this, a joining tool could so far only by replacing the tool set and possibly further alterations for the respectively other joining task be set up.

In the article "Two in one "on page 26 of issue 49/2003 of the industry magazine Maschinenmarkt It reports that it is through the tuning of punch and die geometries possible be, with a single joining device without tool change, alternating clinching and punch riveting points put. In the examples shown, the compounds were in the so-called Tumbling method, i. by a radially superimposed joining movement of the stamp, made. However, the article does not disclose the Geometry of the used tool kit still become constructive Details of the tool used mentioned.

The DE 100 21 781 A1 shows a joining tool with a C-shaped frame, which - can be formed either with a different set of tools and other design changes for punch riveting or for clinching. By an adjustment mechanism on the frame of the punch stroke can be adjusted to adjust the tool to different thicknesses of the workpieces to be joined.

The Invention has in contrast the task is posed, a combined clinching punch riveting tool provide with suitable punch and die geometries, with the without tool change both clinch joints and punched rivet joints can be produced.

These The object is achieved by the invention characterized in claim 1 solved.

The formed according to the invention Tool uses a multi-part die to support the workpieces during the Joining process, which is a basic body with a flat die bottom and several radially outward movable Has die segments which form a round Matrizenausnehmung. Surprisingly It has been shown that with such a die, the general to enforce is used, also punch rivets can be set. Furthermore, the tool according to the invention a stamp to perform of the joining process and a Stempelhubverstelleinrichtung through which the Stempelhub optionally between a punch stroke for the clinching and a stamp stroke for the punch rivet is adjustable. Namely while enforcing the Stamp the workpieces deep-drawn and is therefore sunk into this, the stamp on Punch rivets only up to the surface of the punch side workpiece advanced. The end position of the punch and thus the punch stroke So differ in the two connection methods. ever according to size of the closing head when enforcing, the desired Remaining floor thickness and the type of rivet used (countersunk rivet or Flachkopfniet), this difference can be several millimeters. When combined invention Clinching-Stanznietwerkzeug the punch stroke is therefore adjustable in a corresponding range.

The inventive tool also has a hold-down for pressing the workpieces to the Matrix during of the joining process with a punch channel, in which the punch is longitudinally displaceable. The tool is primarily for a linear stamp movement designed without wobbling, as how has been shown, the propagated in the above article wobbling motion the stamp for producing a Punching and clinching compound not necessary is.

Further, a punching knot feeding for feeding punch rivets of a certain Schaftdurchmes sers in the stamp channel available. Advantageous embodiments of the invention are defined in the subclaims.

Preferably is the nominal diameter of the die recess to the diameter of the stamp matched so that the Matrizenausnehmung the displaced Werkstüfkmaterial when enforcing through radial expansion absorbs. Furthermore, the nominal diameter of the Die recess matched to the geometry of the punch rivet, that the Matrizenausnehmung the displaced workpiece material during punching essentially receives without radial expansion. With "nominal diameter" here is the diameter the Matrizenausnehmung meant in the unexpanded state. As when enforcing with multipart matrix is common practice, the diameter of the stamp so chosen that when enforcing joining the enforced material material is pressed outward while the movable Die segments radially outward expands. Surprisingly It has been shown that such a multi-part die, as they previously only for clinching was used in punch riveting a perfect closing head of the Punch rivet forms when the rivet geometry to the nominal diameter the Matrizenausnehmung is tuned so that the Matrizenaufnehmung the resulting closing head without expanding the movable die segments accommodates. For this In particular, the shaft diameter of the punch rivet to the nominal diameter the Matrizenausnehmung tuned; the type of rivet head - whether countersunk or flat head - can but also be of importance, since also by the countersunk tool material is displaced.

It It has been shown that good connection results essentially without radial expansion of the movable die segments in a Nominal diameter of the die cavity of about 6 mm with punched rivets can be achieved with shaft diameter of about 3 mm. at a nominal diameter of the die recess of about 8 mm preferably a shank diameter of the punch rivet of about 5 mm selected. Preference will be this Countersunk rivets used; However, a connection is also with flat head rivets or other semi-tubular rivets possible.

In an advantageous embodiment of the tool according to the invention lie the centers of the matrix, the punch and the blank holder on a common main axis and the drive consists of a transverse to the main axis extending actuating cylinder and one between the Actuating cylinder and the joining die effective Power transmission mechanism. This embodiment of the frame is a compact, space-saving Construction of the tool possible.

According to one another preferred embodiment is the power transmission mechanism further on an upper frame part, in which the punch and the hold-down are integrated, supported at an upper support point. at this frame geometry leaves the punch stroke preferably adjusted by the fact that the support point is adjusted in the direction of the main axis. That's the way it is possible, the punch stroke and thus the final position of the punch between a for the Clinching and one for to adjust the punched rivet suitable position.

Based The drawings will now be an embodiment of the invention explained in more detail. It demonstrate:

1 a sectional view of a combined push-through punch riveting tool according to an embodiment of the invention;

2 a part of the tool the 1 on an enlarged scale;

3 a side view of a multi-part die;

4 a plan view of a multi-part die;

5 a partial sectional view of a punched rivet.

This in 1 illustrated combined push-through punch riveting tool is used for mechanical joining of two or more plate-shaped workpieces optionally by punch riveting or by clinching (clinching).

The tool basically consists of a frame 2 , a drive in the form of an actuating cylinder 4 and a power transmission mechanism 6 , a stamp 8th , a hold-down 10 and a die 12 that in the 4 and 5 is described in more detail and will be described in detail below.

The frame 2 consists of an upper frame part 2a and a lower frame part 2 B , The upper frame part 2a is designed as a housing, which at its (in 1 ) left end open and otherwise closed. The lower frame part 2 B is C-shaped. The lower leg of the lower frame part 2 B wears the matrix 12 ,

As already mentioned, the drive consists of a positioning cylinder 4 and a power transmission mechanism 6 together, which consists of a toggle mechanism 22 . 24 . 26 consists. The actuating cylinder 4 is about a joint 18 with the back of the cup-shaped upper frame part 2a connected while the piston rod 20 of the adjusting cylinder 4 via a toggle joint 22 with the upper lever 24 and the lower lever 26 the toggle mechanism is connected. The upper lever 24 is over a lying on the major axis A joint 28 at an upper support point on the upper housing wall of the upper frame part 2 supported.

This upper support point is as a screw mechanism 30 formed, via an actuating part 32 manually or by motor is operable to the joint 28 and thus to be able to adjust the upper support point of the toggle mechanism along the main axis A. Since the actuating cylinder works wegbegrenzt, this is the "end position" of the extending punch 8th adjusted. As a result, the punch stroke can be adjusted between a punch stroke for the clinching and a punch stroke for the punch riveting. The required adjustment length between punch rivets and clinching depends on the material thickness, the selected rivet geometry and the residual floor thickness desired during clinching. For example, with a material thickness of 2.5 mm in total, the punch stroke during clinching can be about 2-4 mm longer than when setting a countersunk rivet. The maximum adjustment range of the tool shown is about 8 mm, with the screw mechanism 30 is preferably actuated by an electric motor.

It is now additionally on 2 Referenced. The lower lever 26 the toggle mechanism is provided with a sleeve-shaped housing part 34 hingedly connected to the outside. The housing part 34 in turn is with the stamp 8th firmly connected, made up of a rod part 36 and the actual stamp part 38 composed. Furthermore, the housing part 34 through a linear guide 42 at the frame 2 movably mounted so that the housing part 34 and thus the stamp 8th along the main axis A can be adjusted. The linear guide 42 can be provided in a simple manner with a conventional Wegmessaufnehmer (not shown).

The hold down 10 that the stamp 8th concentric surrounds, on the one hand by the housing part 34 and on the other hand, a mouthpiece part 50 educated. The mouthpiece part 50 forms a stamp channel in which the stamp 10 is mounted longitudinally displaceable. For this purpose, the mouthpiece part 50 through a (eg plastic) guide bushing 56 opposite the stamp 8th and by a (eg made of plastic) guide bushing 58 opposite the housing part 34 slidably mounted.

The mouthpiece part 50 and the housing part 34 be by a spreading spring 60 pressed apart, between the bottom of the housing part 34 and the upper end of the mouthpiece part 50 acts to the mouthpiece part 50 relative to the housing part 34 to press in an extended starting position, in the mouthpiece part 50 on a shoulder 61 of the stamp 8th is applied.

The spreading spring 60 is from a hold-down spring 62 surrounded, between the bottom of the housing part 34 and a stopper part 64 is effective. The stop part 64 that is both relative to the mouthpiece part 50 as well as to the housing part 34 is displaceable, is due to a threaded sleeve 66 on, in the housing part 34 is screwed in and on its inside the bearing bush 58 wearing.

Both springs 60 . 62 are designed as coil springs. As will be explained in more detail, the hold-down spring is used 62 for exerting a hold-down force on the workpieces and possibly for stripping the workpieces after a clinching operation. It is therefore much more trained than the spreading spring 60 , which merely serves the mouthpiece part 50 to press in its unloaded state to its original position. The hold-down spring 62 is by the at the threaded sleeve 66 fitting stop part 64 biased with a force which corresponds substantially to the hold down force to be exerted on the workpieces. The preload of the hold-down spring 62 can be adjusted by adjusting the threaded sleeve 66 to adjust.

The stop part 64 has a predetermined axial distance from a contact surface 68 of the mouthpiece part 50 , so that the force of the hold-down spring 62 only after a corresponding relative shift between the housing part 34 and the mouthpiece part 50 can be transferred to this, as will be explained in more detail below.

Furthermore, in the mouthpiece part 50 a feeder 72 intended for punch rivets.

In the 3 and 4 is the matrix 12 shown in magnification. This consists of a basic body 74 and three radially outwardly movable die segments 76a , b, c, which by a steel spring 78 be held in position. The individual die segments are additionally captive on a template protection on Matrizengrundkörper 74 attached to prevent falling out of the individual segments. In the example shown are three die segments 76a However, the template may also be divided into two, four or more segments. In the unexpanded basic position, the die segments enclose 76a , b, c a round Matrizenausnehmung 80 with a nominal diameter d _nominal . The main body 74 at the same time also forms the flat bottom of the Matrizen recess 80 , The matrix is by means of a pin 82 on the lower frame part 2 B to fix.

As a stamp 8th In the case of the tool shown, a punch suitable for clinching is used which has the shape of a cylinder with a flat end face. The peripheral edge of the end face is rounded so as not to cut the workpiece during deep drawing. As a rule, the stamp has 8th a slightly smaller (eg 5-15% smaller) diameter than the nominal diameter of the die 12 For example, for a die with a nominal diameter of 8 mm, a 7.5 mm die is used. With a nominal diameter of the die of 6 mm, for example, a 5.3 mm punch is suitable. With these dimensions it is achieved that forms an undercut in the clinching point during clinching by the radial expansion of the die segments. The diameter of the clinching point thus formed is about 1.4 times as large as d _rated .

With such a stamp 8th and the in 3 and 4 represented template 12 Punch rivets are also used. An example of a suitable punch rivet 84 is in 5 shown. This is a Halbhohlniet with countersunk, in which the rivet head is sunk so far into the punch side workpiece until the rivet head is aligned with the workpiece surface. The geometry of the rivet is adapted to the die and punch geometries in such a way that the closing head produced during the punch riveting fills the die recess without radially widening the die segments. The diameter of the closing head is then not greater than the d _nominal . It has been found that the rivet shown forms such a closing head when the shaft diameter d _{shaft is} in a specific ratio of approximately 1/2 to 5/8 to the nominal diameter d _{nominal of} the die. In the case of a rivet with a different geometry, eg a flat-head rivet, a different shaft diameter may be more suitable.

Furthermore, care should be taken that the head diameter d _{head of} the punch rivet is not significantly larger than the punch diameter, otherwise form on the rivet head imprints of the punch. Good results were WUR the example achieved with the dimensions shown in the table for punch, die and rivet.

TABLE: Approximate matched values for die, punch and rivet dimensions

The mode of operation of the tool described so far is as follows:
To perform a clinching or stamping riveting operation, the workpieces to be joined (not shown) lie on the die 12 , while (only when punching rivets) on the feeder 72 in the punch channel of the mouthpiece 52 supplied punched rivet in front of the bottom of the stamp part 38 of the stamp 8th lies. Upon actuation of the pneumatically acting actuating cylinder 4 this transmits its driving force to the toggle mechanism 6 on the one hand, via the upper lever 24 at the upper support point on the frame 2 supported on the other hand on the lower lever 26 on the housing part 34 acts. This will be the stamp 8th along with the entire downholder 10 over the linear guide 42 along the main axis A down moves until the mouthpiece part 50 attaches to the workpieces. The mouthpiece part 50 Therefore, it can not move further down, so that in a further extension movement of the actuating cylinder 4 the housing part 34 as well as the stamp 8th relative to the mouthpiece part 50 be moved. This is the spreading spring 60 squeezed accordingly. The preload of the hold-down spring 62 but does not affect the mouthpiece part in this part of the downward movement 50 but is from the on the threaded sleeve 66 supported stop part 64 added.

Just before the punch riveting of the stamp 8th down punched rivet is driven into the workpieces, or when clinching just before the punch 8th is sunk into the overhead workpiece, the stopper part sets 64 to the contact surface 68 on, so that in a further downward movement of the housing part 34 the threaded sleeve 66 from the stopper part 64 solves. The mouthpiece part 50 Then, with the entire biasing force of the hold-down spring 62 against the at the matrix 12 supported workpieces pressed. In the subsequent joining process, the housing part 34 and continue to drive the punch down until the punch rivet or clinch point is set.

During clinching, the punch is first sunk into the workpieces, which limits the joining area and deep-draws the material. By the further advance of the stamp 8th the inserted material material is compressed and flows radially outward, wherein the die segments 76 be radially expanded. To ensure a certain residual floor thickness of the clinch point, the actuating cylinder works 30 wegbegrenzt, leaving the stamp 8th only up to a certain, through the adjustment mechanism 30 previously set end position is advanced.

The provision of the tool is carried out by an opposing action on the actuating cylinder 4 , This takes the lower lever 26 of the toggle mechanism the hold-down 10 and the stamp 8th in its upper position, with the spreading spring 60 the mouthpiece part 50 in its initial position relative to the housing part 34 and the stamp 8th suppressed.

If a punch rivet is to be set after a clinching operation, the end position of the punch becomes 8th through the adjustment mechanism 30 so far moved up, or shortened the punch stroke by so much that the punch is only advanced so far until the punch rivet used is set. In the case of a countersunk rivet, the punch is advanced, for example, until the rivet head is flush with the surface of the punch-side workpiece. With a material thickness of 2.5 mm, this can mean a shortening of the punch stroke compared to the punch riveting by about 2.7 mm. For a flat head rivet, the rivet head height would be added.

Further, for punch riveting, as described above, via the rivet feed 72 added a punch rivet. During the joining process, the punch rivet element punches through the upper workpiece (s) and plastically shapes the lower workpiece to form a closing head. The rivet shank is spread by the compression against the flat Matrizenboden. After reaching the through the adjustment mechanism 30 set punch end position, the return stroke takes place as described above.

With the described joining tool From steel and aluminum alloys it was possible to produce sheets of a total material thickness of e.g. 2.5 mm both by clinching and by punch riveting connect to.

Claims (9)

Combined push-through punching riveting tool for the mechanical joining of at least two workpieces optionally by means of clinching or punch riveting, with a frame ( 2 ), a multi-part die ( 12 ) for supporting the workpieces during the joining process, which comprises a basic body ( 74 ) with a flat die bottom and several radially outwardly movable die segments ( 76a . 76b . 76c ), which has a round die recess ( 80 ), a stamp ( 8th ) for performing the joining operation, a drive ( 4 . 6 ) for actuating the punch, a hold-down ( 10 ) for pressing the workpieces to the die during the joining operation with a punch channel in which the punch ( 8th ) is longitudinally displaceable, a punching netting ( 72 ) for feeding punch rivets ( 84 ) of a certain geometry in the punch channel, and a Stempelhubverstelleinrichtung ( 30 . 32 ), by which the punch stroke is selectively adjustable between a punch stroke for the clinching and a punch stroke for the punch rivet. Tool according to claim 1, wherein the nominal diameter (d _nominal ) of the die recess ( 80 ) on the diameter of the punch ( 8th ) is tuned so that the Matrizenausnehmung ( 80 ) receives the displaced workpiece material during clinching by radial expansion, and on the geometry of the punch rivet ( 84 ) is tuned so that the Matrizenausnehmung ( 80 ) receives the displaced workpiece material during punch riveting substantially without radial expansion. Tool according to claim 1 or 2, wherein the nominal diameter (d _nominal ) of the die recess ( 80 ) on the _shank diameter (d _shank ) of the punch rivet ( 84 ) is tuned so that the Matrizenausnehmung ( 80 ) receives the displaced workpiece material during punch riveting substantially without radial expansion. Tool according to claim 3, wherein the nominal diameter (d _nominal ) of the die recess ( 80 ) about 6 mm and the shaft diameter of the punch rivets ( 84 ) is about 3 mm. Tool according to claim 3, wherein the nominal diameter (d _nominal ) of the die recess ( 80 ) about 8 mm and the shank diameter of the punch rivets ( 84 ) is about 5 mm. Tool according to one of the preceding claims, in which the centers of the die ( 12 ), of the stamp ( 8th ) and the hold-down ( 10 ) lie on a common main axis (A) and the drive ( 4 . 6 ) from a transverse to the main axis (A) extending actuating cylinder ( 4 ) and an effective between the actuating cylinder and the punch power transmission mechanism ( 6 ) consists. Tool according to one of the preceding claims, wherein the power transmission mechanism on an upper frame part ( 2a ) into which the stamp ( 8th ) and the hold-down ( 10 ) are supported at an upper support point. Tool according to claim 7, wherein the punch stroke by adjusting the support point is adjustable in the direction of the main axis. Tool according to one of the preceding claims, in which the stamp ( 8th ) has the shape of a cylinder with a flat end face having a rounded peripheral edge.