EP0391114B1 - Device for punching out and forming butterfly-clamps from steel strip - Google Patents

Abstract

The invention describes a machine in which butterfly clamps (19) are punched out of steel strip and simultaneously bent, thus being fixed on fixing means (26) of a frame (31) of a spring core. <??>The same tool is thus used both for punching out the clamps and for the bending process, i.e. the process of establishing a connection between the parts of the spring core. The machine is thus particularly economical in operation because, compared to the prior art, the separately punched-out butterfly clamps do not have to be inserted into a separate bending machine.

Description

The invention relates to a machine for punching and deforming butterfly clips from steel strip, according to the preamble of claim 1. Such a machine oil known from DE-A-1060 828.

So-called butterfly clips are used to connect the outer edge of a spring core and the edge springs located there with a surrounding frame.

So far, it has been customary to punch the butterfly clips out of steel strip in such a machine and then to connect them to the parts of the spring core. Care must be taken to ensure that the clamps are correctly positioned on the parts of the innerspring.

The invention for punching out and deforming butterfly steel mallets from strip steel avoids these disadvantages. It is based on the task of proposing a machine in which the butterfly clips can be punched out of the steel strip as well as securely connected with the fastening means of the spring core.

To achieve this object, the invention is characterized in that the profiled working bending surface of the first punching knife (9) has a cutting curve (12) with a cutting edge (30) in the form of a trapezoid and lateral cutting edges for reaching under and bending the punched-out tabs (20, 31) of the butterfly clip (19), that the second punching knife is a nose (8) with a trapezoidal cutting edge (30) and horizontal cutting edges (40), and that a hold-down device (13.) That can be set and locked with the first punching knife (9) ) is provided.

The essence of the invention is therefore the combination of a punching tool with a bending tool in one and the same machine in such a way that in this machine both the butterfly clips are punched out of the strip steel and also bent at the same time, i.e. be connected to parts of the spring core or the spring core frame.

If the fastening means for fastening the butterfly clip to the innerspring frame consist of round frame wire and round spring wire, the work table can be fixed to the frame. However, if the fastening means are designed as a round spring wire, combined with a spring frame with a flat profile, the work table can preferably be raised and lowered. In this embodiment, there is therefore an adaptation to the rectangular flat profile of the flat frame, in which the steel strip is first pre-bent and the pre-bent steel strip is then lifted over the work table and finished bent.

Further details and important features of the invention emerge from the following description of examples.

• Figur 1: eine Seitenansicht der wichtigsten Bauteile einer Maschine zur Verbindung eines Rahmendrahtes mit einem Federdraht mit Hilfe der Butterflyklammern, die in derselben Maschine aus Bandstahl ausgestanzt werden;
• Figur 2: einen Schnitt längs der Linie II-II von Figur 1;
• Figur 3: eine Draufsicht auf die flache Butterflyklammer, wie sie in dieser Maschine ausgestanzt wird;
• Figur 4: eine Ansicht entsprechend Figur 1, wobei gezeigt ist, daß die Klammer zu einem in sich geschlossenen Gebilde gebogen ist und damit die Verbindung herstellt;
• Figur 5: eine Ansicht entsprechend Figur 1 bei einer demgegenüber abgeänderten Ausführungsform mit heb- und senkbarem Arbeitstisch;
• Figur 6: einen Schnitt längs der Linie VI-VI von Figur 5;
• Figur 7: eine Ansicht entsprechend Figur 4 bei dieser zweiten Ausführungsform.

Show it:

• 1 shows a side view of the most important components of a machine for connecting a frame wire to a spring wire with the aid of the butterfly clips which are punched out of steel strip in the same machine;
• Figure 2 shows a section along the line II-II of Figure 1;
• Figure 3 is a plan view of the flat butterfly clip as it is punched out in this machine;
• Figure 4 is a view corresponding to Figure 1, showing that the clip is bent into a self-contained structure and thus creates the connection;
• FIG. 5: a view corresponding to FIG. 1 in a modified embodiment with a work table that can be raised and lowered;
• 6 shows a section along the line VI-VI of Figure 5;
• Figure 7: a view corresponding to Figure 4 in this second embodiment.

In FIG. 1, a punch knife guide 10 is arranged on a machine stand 27, as well as a pre-bender 4, which is firmly connected to the machine stand 27.

A work piece or a center piece 5 is arranged on the pre-bender 4, the two parts 4, 5 formed between them forming a gap 6 into which the steel strip 1 is pushed in the direction of the arrow 3. The feed takes place via a guide part 2, the strip steel being advanced by a clamp length 37 (see FIG. 3).

The definition of the clip length 37, namely from the tip of the flap 23 in FIG. 3 to the bottom of the recess 24 in FIG. 3, also shows that you gain a substantial material saving if you punch a clip 19 according to Figure 3 from the steel strip 1 directly.

At the exit of the gap 6 a bending surface 7 is arranged, at the upper end of which a surface 16 is arranged.

The purpose of this bending surface 7 is to pre-bend the clamp 19 to be processed later, as is shown in dash-dot lines with the radius in FIG. 1.

In the position shown in Figure 1, the tool is in the starting position, i.e. before making the die cut.

On the punching knife guide 10, a punching knife 9 is slidably mounted in the direction of arrow 11 and in the opposite direction.

A hold-down device 13 is firmly connected to the punching knife 10 by means of a screw connection, and - as will be explained later - the hold-down device 13 can be vertically adjusted and locked in the direction of the arrows 15.

The punch knife 9 and the hold-down device 13 are driven via a drive plunger 17 which engages in a recess 18 in the punch knife 9, the drive plunger 17 being driven and pivoted about the pivot point 36 by means of an articulated lever (not shown).

At the front end of the punching knife 9, a cutting curve 12 is provided, which has the shape of a trapezoid, namely the shape of the recess 24 in the bracket 19, as shown in FIG. 3.

On the side of the cutting curve 12, which has a projection which corresponds to the recess 24 of the clamp 19, there are lateral knife edges which cut on the one hand and bend on the other hand and in this case make the cut 38 at the outer ends of the tabs 21 of the clamp 19.

These cutting edges, which make the cut 38, serve at the same time to reach under the tabs 21, 22 which, as can be seen in FIG. 4, are thereby bent around the frame wire 25, which is placed on a table 34.

The remaining surfaces of the clamp 19 then encompass the frame wire 25, including the spring wire 26, it being important that the front tab 23 engages precisely in the recess 24 in the bent state.

This ensures that the clamp 19 cannot slip at an angle or can be bent apart at an angle, and this ensures an excellent and firm connection of the two parts 25, 26 mentioned.

The tool now performs a punch cut by moving the punch knife 9 in the direction of the arrow 11 and punching out the tabs 20, 21 lying opposite one another in connection with the recess 24 arranged therebetween. For this purpose, a fixed nose 8 is arranged in the area of the center piece 5, which corresponds exactly to the shape of the recess 24. So there is no band steel waste, because what is punched out of this band steel in the area of the nose is the tab 23 of the following bracket.

It is important that the holding-down device 13 is arranged above the punching knife, the lower edge 29 of the clamp 19 in the brings it into the correct position and prevents the clip from escaping upwards, so that it is bent over the parts 25, 26, as shown in FIG.

Here, the parts 25, 26 together with the clamp 19 are pressed against the bending surface 39 of the bending piece 14, which bending piece 14 is fastened on the center piece 5.

This therefore ensures that the front, bent part of the clamp 19, which is on the right in the drawing in FIG. 1, is deflected downward from the bending surface 39; so that the tab 23 is bent clockwise into the recess 24.

From Figure 2 it can be seen again that a trapezoidal cutting edge 30 is provided in the area of the nose 8, which punched out the recess 24 in the bracket 19.

Horizontal cut edges 40 adjoin the side of this trapezoidal cut edge 30, which make the cut 38 on the tabs 20, 21. These cut edges 40 serve, as described above, to reach under and bend these tabs 20, 21.

Figure 4 shows the end of the machining cycle, i.e. the punching knife 9 has moved in the direction of the bending piece 14 and has also slightly taken the clamp 19 and the two parts 25, 26 to be connected in the direction of the arrow 11.

It can be seen that the plunger 17 has changed its position.

It can be seen that the clamp is non-positive and positive the two parts 25,26 connects with each other and by engaging the tab 23 in the associated recess 24, an excellent connection secured against slipping is hereby created.

FIGS. 5-7 show a further embodiment of a punching and bending tool, the same reference numerals being used for all parts. There is therefore identity between the parts compared to FIGS. 1-4 with the exception of the following features:

To connect a flat frame 31 to an associated spring wire 26, both the punch knife 9 and the bending piece 14 are modified.

A recess 33 is provided in the area of the punching knife 9, which corresponds to an assigned recess 32 in the bending piece 14.

The flat frame 31 here lies on a table 34 which can be raised and lowered, the table 34 being able to be raised and lowered again in the direction of the arrow 35.

In an embodiment not shown in detail, the lifting and depositing is carried out in such a way that the table 34 is pivotably mounted on the machine housing via a corresponding drive.

In the position shown in FIG. 5, when the punch knife 9 is advanced, the previously described punch cut is again made to produce the clamp 19.

The bracket has its position as shown in Figure 5.

In order to now connect the flat frame 31 to the spring wire 26, the table 34 is raised to its position 34 'in the direction of the arrow 35 and the recess 33 in the punching knife 9 thus comes into alignment with the recess 32 in the bending piece 14.

The punching knife 9 thus remains at the same level with its recess 33, only the flat frame 31 is lifted together with the spring wire 26 lying thereon in connection with the table 34, the bending piece 14 remaining fixed to the frame, i.e. is not raised.

The reason for lifting the parts 25, 26 in connection with the table 34 is therefore that one initially wants to achieve an ideal, curved bending curve, as shown in FIG. Care should be taken to ensure that the bent, upper part of the clamp overlaps the flat frame 31 with the spring wire 26 lying thereon in the position shown.

Only by lifting the two parts mentioned and by introducing this pre-bent part into the two opposite recesses 32, 33 is the clamping itself carried out, thereby ensuring a secure clamping.

In the embodiment according to FIGS. 1-4, such a lifting was not necessary because the round design of the frame wire 25 and spring wire 26 already gives a pre-bend, while in the rectangular profile of the flat frame 31 the clip is first bent round and then by the action of the two opposite recesses 32, 33 the bracket is first bent at an angle or flat.

Claims (4)

1. A machine for the punching out and deformation of butterfly clips (19) of strip steel (1), consisting of a first punching blade (9) with a profiled working bending face, of a second punching blade, a guide piece (2), which advances the strip steel (1) in the length of the clip, a pre-bender (4), which forms the strip steel, before shearing off partially into a circular arc section about workpieces which are to be connected, which are supplied transversely to the strip steel (1), a work table (34), and a bending piece (14), with a profiled working bending face (32,39), which bends the pre-bent butterfly clip (19) together with the working bending face of the first punching blade (9) into a final position on the workpieces which are to be connected,
   characterised in that
   the profiled working bending face of the first punching blade (9) has a cutting curve (12) in the form of a trapezium and lateral cutting edges for engaging beneath and bending the punched out tongues (20,21) of the butterfly clip (19),
   that the second punching blade is a nose (8) with a trapezoidal cutting edge (30) and horizontal cutting edges (40), and
   that a holding-down device (13) is provided, which is able to be adjusted and secured with the first punching blade (9).
2. A machine according to Claim 1, characterised in that the nose (8) of the second punching blade before the punching-out process is arranged within the circular arc section of strip steel (1).
3. A machine according to Claim 1, characterised in that the work table (34) is fixed to the frame.
4. A machine according to Claim 1, characterised in that the work table (34) is able to be tilted or respectively is able to be raised and tilted.

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