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[ EN ]

Method and assembly for continuously operating production of box-section and frame structures

The present invention relates to a method according to 5 the preamble of claim 1 for continuously operating
production of box-section and frame structures from
multiple mutually joinable members.

The invention also concerns an assembly for the assembly 10 of such structures according to the preamble of claim 8.

As the first step in the production of box-section and
frame structures such as window and door jambs, batches
of required numbers of suitable jamb members have conven- 15 tionally been fabricated in the above-described manner by working them in different machines, after which the
members have been transferred to buffer stores. From the stores the members have been retrieved on the basis of
received orders and assembled into ready jambs in
20 assembly jigs. The conventional methods typically require several steps of length trimming of material and cutting of blanks, and the overall automation of such processes
has therefore turned out to be difficult.

25 None of the automated processes known in the art have
either been successful in all respects. An automated
production process to be noted as an example is the
DSH 16 machining line by Maschinenfabrik Gubisch GmbH in which the workpieces travel along tracks on which they

30 have to be reversed for working the other end. Such
forward and reverse movements slow down the production
rate and reduce the throughput capacity of the process.

* It is an object of the present invention to overcome the 35 disadvantages of prior-art technology and to achieve an
entirely novel method for producing box-section and frame structures, said method facilitating the automation of the production process.

The method is based on the concept of producing each member of the frame in a continuous process adapted to the assembly order of the members. The novelty of the embodiment according to the invention lies in the interfacing of a number of successive functions: The combination unit of an extension joint cutter and a glue appli- cator produces a continuous blank of material stock, which is trimmed to pieces of desired length. A two-way machining unit equipped with at least two cutter heads works the pieces to have a continuous sequence of male- female-male-female joint portion combinations in proper assembly order. When necessary, the pieces can be worked in said sequence to a desired sectional shape, which furthermore can be varied at any instant, even permitting the working of each successive piece of a frame into a different shape. Finally, the desired products are assembled from the pieces fed to the assembly in the proper order.

More specifically, the method in accordance with the invention is principally characterized by what is stated in the characterizing part of claim 1.

Furthermore, the assebly according to the invention is characterized by what is stated in the characterizing part of claim 8.

The production line is formed according to the invention by first connecting in series two machining stations, called two-way machining units by their function, of which the first can perform the joining of sawn lumber into a continuous stock by glue joints and the second is adapted to perform the continuous working of properly sequenced pairs of joint ends to the frame members. The joint portions at the member ends to be joined are worked by cutter heads or similar tools in successive work phases and the order of the members moving in succession on a conveyor is maintained proper even at this stage so that the order of the members is automatically the same as their proper assembly order into a frame.

In an advantageous embodiment of the invention, the members are worked in the machining units without changing their longitudinal orientation. The transfer of the members through the first and second machining unit in particular is arranged to occur by successive longitudinal and lateral movements, whereby the working of the members takes place substantially during the lateral movements only.

The above-mentioned first machining station is, e.g., such an equipment that has one permanently mounted cutter head and a support table, which is vertically movable relative to said cutter head and on which table the workpieces are moved, whereby the elevation of the support table is changed after working the joint portion to the member's front end by an offset of half finger spacing of a finger joint so as to form compatibly different finger joint portions to the front and rear ends of the members, respectively.

The second machining unit is, e.g., such an equipment that has two permanently mounted, mutually different cutter heads and a support table having a fixed elevation relative to said cutter heads, whereby the members are moved on the support table in an alternating order past the two alternative cutter heads so as to form compatibly different joint portions to the ends of every second member, respectively. Alternatively, the second machining unit can be provided with four separate cutter heads, of which each pair comprises two mutually different heads.

When necessary, the sectional shape of the members exiting the second machining unit can be worked in a third machining unit. Then, the members are moved along a longitudinally oriented transfer track past said third machining unit, in which the members are worked in such series arranged shaping units that are adapted movable between a free-port position and a work-port position of the units, whereby a shaping unit moved to its work-port position is employed for working a single kind of
sectional shape only on the passing workpieces.

More detailed description of the construction and function of above-mentioned machining stations is to be found in parallel patent applications filed by the inventors.

The invention provides significant benefits. Thus, the above-described machining line makes an automated production of each frame with all components possible without the use of a buffer store, whereby the production line can be employed for fulfilling a purchase order involving a great number of different sectional shapes and frames at the same throughput speed and cost as an order of equivalent size comprised of a single product only.

According to the present invention, the integrated operation of the production line is implemented using equipment of entirely novel construction that is capable of providing the continuously operating fabrication of products according to the above-described scheme featured by a nonstop change of product characteristics and omission of buffer stores.

The invention is next examined in detail with the help of the appended drawing which shows the diagrammatic con-struction of the production line according to the invention in a side view.

Using the reference numerals of the diagram, the production line according to the invention comprises the following apparatuses adapted to a series connected system: A feeder 1 of wood blanks, a machining unit 2 comprised a so-called two-way machining unit with one or two cutter heads for cutting extension joint portions, a gluing and clamping unit 3 for making extension joints, a cross-cutting saw 4 for cutting stock to dimension, a calibrating joiner 5, a miter cutter apparatus 6 comprised of a so-called two-way machining unit with two or four cutter heads, and a shaping cutter unit 7. The apparatuses are series connected to each other by means of conveyors 8.

The operation of the production line is steered by a control unit (not shown), which is employed for, i.a., computing the dimensions of members to be worked from the dimensions of the structure to be produced, e.g., the size (height x width) of a frame. This information is used for controlling the operation of the cross-cut saw 4 for cutting stock to dimension, and the finger joint machining apparatus 6.

A central unit of the production line is the finger joint machining apparatus 6 whose operating principles were outlined above and are closer described in a parallel patent application. An essential characteristic is that the orientation of the workpieces is not altered during working, but rather, the pieces are transferred through the apparatus by means of longitudinal and lateral movements, whereby working takes place during the lateral movements. The apparatus can have only a single cutter head, two parallel-mounted cutter heads or four cutter heads mounted to the corners of a rectangle. The system illustrated in the drawing incorporates such an
alternative that has two cutter heads 9 in parallel. The workpiece entering the finger joint machining apparatus 6 is first transferred laterally relative to the cutter head 9 and then further laterally to perform the first working operation. Next, the workpiece is moved forward by at least the length of the piece so as to transfer it to the exit side of the apparatus. Finally, the workpiece is moved laterally to the opposite direction, whereby it is worked at its other end (trailing end) .

The production line according to the invention functions as follows:

Lumber 10 of limited length retrieved from a store by means of a suitable transfer device 11 is first formed into stock 12 of continuous length. This is implemented so that the lumber ends are first worked for the joint portions necessary for, e.g., finger joints. The working operation is performed in an extension joint machining unit 2 so that all lumber pieces received from a feed apparatus 1 are worked for a female joint portion to one end of the piece and a male joint portion to the other, after which both joint portions of successive pieces are glued together in the "head-to-tail" fashion in a gluing clamp. Both joint portions of the extension joint can be worked in a machining unit of the above-described type equipped with two or four cutter heads. It is, however, also possible to produce the extension joint in a two-way machining unit 2 having only one cutter head so that the machining unit is provided with a phase-shift working facility, which alternately works the female portion or the corresponding male portion of the finger joint to the workpiece ends by said phasing arrangement, advantageously by altering the elevation of the support table for half finger spacing or similar repeating element of the joint.

After the gluing press unit 3 , the stock is cut to pieces of predetermined lengths computed by a control unit, whereby the cutting order of the pieces is the same as the assembly order of the members in the final product. Thus, for cutting the member of a window frame, the pieces are cut in, e.g., the following order: a member corresponding to the bottom rail, next a stile, then a top rail and finally the second stile per each frame. This cutting order follows the natural rotating assembly order of the frame. If the frame is to be assembled in a differing order, the cutting order is modified

After cutting, the production line has a calibrating joiner unit 5, in which deviations in the stock shape caused by the gluing press unit (or deviations existing in the lumber of limited length from the start) are worked away.

The ends of the workpieces of predetermined length produced in the above-described manner are worked in the finger joint machining unit 6 for the joint portions, e.g., female-male portions necessary for the assembly of the frame structure. By virtue of the above-described construction and function of the apparatus, the proper order of the workpieces can be maintained during working.

After the working of the joint portions, if necessary, the pieces are routed to a shaping joiner apparatus that works the desired sectional shapes on the pieces. The apparatus 7 acting as the shaping joiner has several successive shaping units which can be set in either of two different operating positions, namely, a free-port position or a work-port position. In the free-port position a passageway* is formed through which the workpiece can freely pass, while in work-port position the cutter head of said shaping unit is caused to work the passing piece. Thus, only a single kind of sectional shape can be worked by each shaping unit. Therefore, the production line according to the above description always has a number of shaping units that are not activated for a passing workpiece. For production of single workpieces this represents a seeming overdimensioning and overcapacity. Such disadvantages are, however, minor with respect to the option of extremely quick change of sectional shape.

The workpieces pass through the shaping joiner along a linear track formed by a succession of free-port and work-port passageways, whereby the mutual order of the pieces is maintained unchanged.

After the shaping joiner the pieces are assembled into desired structures in an assembly unit.