EP0174381B1 - Print hammer bank of modular construction - Google Patents

Description

The invention relates to a print hammer bank in a modular design for known electromagnetic print hammer drives of the type described in the preamble of claim 1.

These electromagnetic pressure hammer drives are based on the principle described in European patent application EP-A-0021335 in connection with FIGS. 1a, 1b, 2, 3, 4 and 6. This application relates to a fast electromagnetically actuated plunger drive, which can be used in particular for impact printers. The electromagnet basically consists of essentially symmetrically constructed magnetizable yoke halves with a corresponding excitation coil (s). The facing pole ends of the yoke halves form aligned magnetic working gaps. A plunger which is displaceable in the direction of the alignment of the working gaps is arranged between the magnetic working gaps. The cross section of the ram is adapted to the area of the working column. It can be (cylindrical or) cuboid. It contains e.g. (Disk or) cuboid anchor elements made of magnetizable material and spacing elements arranged between them made of predominantly non-magnetizable material. The anchor elements have such a geometric design that their volume is in the order of magnitude of the working gap volume. In the initial position of the plunger, the armature elements are essentially in front of the working gaps when the electromagnets are not excited. When the electromagnet is excited, they are drawn into this working gap and experience an acceleration. In arrangements of this type, the plunger moves in a straight line.

A distinction is made between cylinder-shaped and tongue-shaped plungers in the case of printing hammer drives of this type. ^-

Tongue-shaped plungers come into consideration for the present invention.

European patent application EP-A-0062765 describes a bench for accommodating ram units lying next to one another. These each consist of a flat, narrow frame. A tongue-shaped tappet, which is driven by an electromagnetic drive unit, runs within a recess in the frame. For receiving and guiding the individual ram units, the bench comprises a receiving rail and a comb-like holding rail, between which the frames are arranged. Attachments of the lower frame parts can be received by slots in the receiving rail. The upper frame parts are held in incisions in the comb-like holding rail. The tongue-shaped plungers are guided laterally through the electromagnetic drive units arranged on both sides of the frame and aligned with one another. Such a print hammer bank has a number of disadvantages:

Elaborate production, complicated interchangeability of the ram units and susceptibility to vibration.

From the publication IBM Technical Disclosure Bulletin, Volume 25, No. 11 B, April 1983, page 6284-6285, a printing hammer bank with a lower and an upper module of the same geometric rectangular shape is known. Working gaps to accommodate adjacent print hammers are defined between the modules. The working gaps are formed between opposite pole ends of the modules; the electromagnets assigned to them (with a greater width than the print hammers) are mutually offset within a module.

DE-A-2713514 describes a printing hammer bank in which several hammers lying next to one another, each carrying a spool, are combined to form a module.

The coil experiences an electromagnetic action with respect to a magnetic field formed between permanent magnets. The coils are staggered; the modules are rectangular.

• 1. die Druckhammerstössel möglichst dicht nebeneinander liegen sollen
• 2. die Ankerstege in den Druckhammer-Druckstösseln der hier verwendeten Art wegen der für den Druckvorgang zu entfaltenden Kraftwirkung möglichst breit sein sollen, das heisst, sie sollen sich möglichst über die ganze Breite (quer zur Stossrichtung) des Druckhammerstössels erstrecken.

However, printing hammer banks with rectangular modules have the following disadvantages. It is assumed that

• 1. the pressure hammer tappets should be as close as possible to each other
• 2. The anchor bars in the pressure hammer rams of the type used here should be as wide as possible because of the force to be developed for the printing process, that is, they should extend as far as possible over the entire width (transverse to the direction of impact) of the pressure hammer ram.

For reasons of space, however, the electromagnet units assigned to the anchor bars always have a width which exceeds the width of the anchor bars or the pressure hammer ram.

In order to be able to arrange the pressure hammer tappets as closely as possible, it is therefore necessary to move the electromagnetic units against one another.

However, this would cause a problem when using rectangular modules:

The electromagnetic units for the print hammer tappets lying on the edge of the module would protrude above the modules or, if this should be avoided, the mutual distance between the print hammer tappets would have to be increased (which is undesirable). In the former case, it would not be possible to juxtapose adjacent modules without gaps.

It is therefore an object of the invention to avoid these disadvantages.

This object is achieved according to the invention by the measures described in the characterizing part of patent claim 1, which require a parallelogram-like module design.

Further advantageous embodiments of the invention can be found in the subclaims.

The advantage of the parallelogram-like shape is particularly evident when the pressure hammer tappets are to be arranged particularly tightly, almost without gaps. Such a dense arrangement is i.a. Required for impact printers with all-round dot-print character tapes. With such printers, the side gap between the print hammer tappets determines the resolution of the printed dot characters.

The parallelogram-shaped modules according to the invention allow the modules to be placed against one another with almost no gaps and the gap between the plunger and the hammer being almost complete. In the area of the touching sides of two neighboring modules, the pressure hammer joints “rest” on both modules.

In addition, all modules, both in the upper and in the lower row, have the same shape and the same geometric structure, which has significant advantages for production and maintainability.

Each module, encapsulated in plastic, has pole faces of electromagnetic yokes arranged in columns. The magnetic working gaps are formed between the aligned pole faces of the modules of an upper row of modules and the modules of a lower row of modules. Adjacent modules are interlocked. A tongue-shaped plunger (pressure hammer) is assigned to each gap in the modules. Each print hammer has a series of anchor bars. Each tie bar is assigned to a working gap. A working gap is formed between a pole face of a module in the upper row of modules and the pole face of a module in the lower row of modules. For reasons of a high packing density, the electromagnetic units for pressure hammers lying next to one another are arranged offset in the modules. This also results in a mutual offset of the anchor webs of adjacent pressure hammers.

If the plastic in which the modules are cast is made of a good heat-conducting material, there is very good heat dissipation in the pressure hammer bank.

An embodiment of the invention is shown in the drawings and will be described in more detail below.

• Fig. 1 eine schematische perspektivische Darstellung einer Explosionszeichnung der unteren und oberen Modulreihe der Druckhammerbank mit dazwischen nebeneinander angeordneten Druckhämmern;
• Fign. 2A und 2B eine schematische perspektivische Darstellung einer Modul-Basisplatte, wobei
• Fig.2A die den Druckhämmern zugewandte Seite und
• Fig.2B die den Druckhämmern abgewandte Seite zeigt;
• (Fig. 2B versteht sich als Darstellung der um 180° um die Achse 1 gedrehten Modul-Basisplatte nach Fig. 2A.)
• Fign. 3A und 3B eine Aufsicht auf in der Druckhammerbank nebeneinanderliegende Druckhämmer, bei denen die für den Antrieb wirksamen Ankerstege gegeneinander versetzt sind;
• Fig. 4 eine schematische perspektivische Darstellung einer Explosionszeichnung der Elektromagnetspuleneinheit, bestehend aus zwei U-förmig nebeneinander angeordneten Jochen, deren benachbarte Schenkel von einer Spule umfasst werden;
• Fig. zwei nebeneinanderliegende Modul-Basisplatten der oberen Modulreihe in perspektivischer Darstellung mit einem Blick auf die den Druckhämmern zugewandte Seite;
• Fig. zwei nebeneinanderliegende Modul-Basisplatten der unteren Modulreihe in perspektivischer Darstellung mit einem Blick auf die den Druckhämmern zugewandte Seite;
  • (Bei der zusammengebauten Druckhammerbank kann man sich die Modul-Basisplatten gemäss Fig. 5 um 180° um die gedachte Achse 2 derart gedreht denken, dass zwischen den Modul-Basisplatten nach Fig. 5 [gedreht] und denen nach Fig. 6 ein Abstand zur Aufnahme der Druckhämmer bleibt.)
• Fig. 7 eine ausschnittsweise schematische perspektivische Darstellung eines zwischen der oberen und unteren Modulreihe liegenden Druckhammers.

Show it:

• Figure 1 is a schematic perspective view of an exploded view of the lower and upper row of modules of the print hammer bank with print hammers arranged next to each other in between.
• Fig. 2A and 2B is a schematic perspective view of a module base plate, wherein
• 2A shows the side facing the print hammers and
• 2B shows the side facing away from the pressure hammers;
• (FIG. 2B is a representation of the module base plate rotated by 180 ° about axis 1 according to FIG. 2A.)
• Fig. 3A and 3B show a top view of printing hammers lying side by side in the printing hammer bank, in which the anchor webs which are effective for the drive are offset relative to one another;
• 4 shows a schematic perspective illustration of an exploded drawing of the electromagnetic coil unit, consisting of two U-shaped yokes arranged next to one another, the adjacent legs of which are encompassed by a coil;
• Fig. Two adjacent module base plates of the upper module row in a perspective view with a view of the side facing the print hammers;
• Fig. Two adjacent module base plates of the lower row of modules in a perspective view with a view of the side facing the print hammers;
  • (In the assembled print hammer bank, one can think of the module base plates according to FIG. 5 rotated by 180 ° about the imaginary axis 2 such that there is a distance between the module base plates according to FIG. 5 and those according to FIG. 6 The hammers remain in place.)
• Fig. 7 is a fragmentary schematic perspective view of a print hammer located between the upper and lower row of modules.

Fig. 1 shows a schematic perspective view of an exploded view of the lower and upper row of modules of the print hammer bank with print hammers arranged side by side between them.

Modules 7, 8, 9, 10 of identical form are used to form the print hammer bank. Adjacent modules 9 and 10 form an upper row 3 of the print hammer bank and adjacent modules 7 and 8 form a lower row 4 of the print hammer bench. The upper 3 and lower 4 row of modules are spaced apart. Between them are pressure hammers arranged side by side, of which only two, 5 and 6, are shown in FIG. 1. The direction of action of the print hammers is indicated by the arrow direction D. Each module 7, 8, 9, 10 has a plurality of pole faces PF of electromagnetic yokes on the side facing the pressure hammers. The pole faces of the upper row of modules are aligned with the pole faces of the lower row of modules. A large number of magnetic working gaps are defined by the spaced pole faces of the upper and lower row of modules. These working gaps are activated by an appropriate electromagnetic coil excitation.

The pole faces are arranged in columns (C). In Fig. 1, each column of a module has four pole faces. The print hammer (detailed illustration in FIGS. 3A and 3B) has as many soft iron webs (anchor webs) as in FIG there are working gaps defined by pole faces assigned to it; in the given embodiment also four pieces. The distance between the soft iron bars in a print hammer corresponds to the distance between the working columns in the corresponding column of the print hammer bank. In the rest position of the print hammer, its soft iron webs lie in front of the working gaps assigned to them, which are formed by opposite pole faces of the modules.

When the magnetic working gaps for a printing hammer are activated, the anchor webs of the printing hammer are drawn into the working gap and accelerated in the process, so that the printing hammer undergoes a drive movement in the printing direction D. The modules of a row of modules are interlocked. The upper 3 is spaced from the lower 4 module row by appropriate spacing elements to form the working gaps. The modules of the top 3 and bottom 4 rows are held together by appropriate screw, rivet or similar connections. Such connections can e.g. through the through-holes marked P1 / P2, P3 / P4, P5 / P6, P7 / P8. A large number of connections 46 for the electromagnetic units are provided on the side of the modules facing away from the pressure hammers. The following details are given about details of the electromagnetic units, the spacing elements for the module rows, the form-fitting connection of the modules within a module row and about the structure and structure of the modules.

The column boundary identified by 72 is described in detail in connection with FIG. 7.

A module consists of a module base plate (e.g. 11 for module 7) and a part 12 connected to it, in which the electromagnet units 30 (FIG. 4) are arranged or potted with it. As already mentioned, adjacent modules are positively connected to each other in the print hammer bank. bie pole faces of the modules are arranged in columns (C in Fig. 1). A print hammer is assigned to each column.

For reasons of tight packing, the electromagnetic units for adjacent module gaps are offset from one another.

Seen from above, the identical form of the modules is based on a modified parallelogram. It permits a close packing density of the side-by-side pressure hammers, the anchor webs of which are also offset from one another in accordance with the pole faces (or electromagnet units) which are offset from one another in adjacent columns. If all modules of the print hammer bank are identical in shape, both in the upper and in the lower module row, the number of print hammers per module is always even.

FIG. 4 shows a schematic perspective illustration of an exploded drawing of a magnet coil unit. It consists of two yokes 31 and 32 arranged next to one another in a U-shape, the adjacent legs of which are encompassed by a common coil 45. The coil carrier consists of a diamond-shaped base plate 50 and an upper cover plate 49. Both plates are connected to one another by two spacer elements 48 and a centrally arranged hollow body 81. The spacer elements 48 are connected beyond the base plate to contact pins 46 for the electrical connections of the coil 45. The base plate 50 has openings 74 and 75 for the passage of the outer yoke legs of the pair of yoke legs 31, 32 and an opening in the region of the hollow body 81 for receiving the adjacent yoke legs of the pair of yoke legs 31, 32. In the cover plate 49, four openings 41, 42, 43, 44 are provided for receiving the leg ends of the yokes 31 and 32. After inserting the yokes into the coil former and then fixing them, e.g. by casting in plastic, the yoke ends protrude slightly above the upper cover plate 49.

The following describes how the electromagnetic units and the module base plates are connected to each other.

The figures 2A and 2B show a schematic perspective illustration of a module base plate, with FIG. 2A showing the side facing the print hammers and FIG. 2B showing the side facing away from the print hammers. FIG. 2B is understood to be a representation of the module base plate according to FIG. 2A rotated through 180 ° about axis 1. While a perspective top view of the module base plate is shown in viewing direction U in FIG. 2A, a top view of its underside in viewing direction B can be seen in FIG. 2B. The pole faces in a column are formed by the four ends of the yokes of a pair of magnetic yokes 31, 32. These ends are labeled 31-1, 31-2, 32-1 and 32-2 in Fig. 4. The electromagnet units are plugged on with the top surface 49 first on the back of the module base plates in direction B, so that the yoke ends 31-1 to 32-2 in which protrude slightly from the openings 41, 42, 43 and 44 beyond the top surface 49 of the electromagnet unit the openings corresponding to them (the pole faces in the openings of the first and second columns in FIG. 2A correspond to the pole ends of the electromagnet unit with [32-1], [32-2], [31-1] and [31-2] a column in the module base plate. The yoke ends are inserted into these openings until their pole face is flush with the plane of the module base plate. It should be noted repeatedly that an electromagnetic unit is provided for each module column.

For reasons of a high packing density, the electromagnet units are arranged staggered for adjacent module gaps. As a result, the pole faces of adjacent module columns are also offset from one another. Two electromagnets offset against each other units are indicated in Fig. 2B by the dashed contours of their cover plates.

Fig. 5 shows two adjacent module base plates of the upper module row in a perspective view with a view of the side facing the pressure hammers. The left base plate 9 has extensions 93 and 94 on its left side and cutouts 91 and 92 on its right side. For the right base plate 10, the extensions are marked with 103, 104 and the cutouts with 101 and 102. The extensions and recesses have such a shape that they fit into one another in a form-fitting manner.

Fig. Shows two adjacent module base plates 7 and 8 of the lower module row in a perspective view with a view of the side facing the pressure hammers.

In the assembled print hammer bank, the module base plates 9 and 10 according to FIG. 5 can be thought to be rotated by 180 ° about the imaginary axis 2 such that there is a distance between these module base plates in the rotated state and those 7, according to FIG. 6 Recording of the print hammers remains.

FIG. 7 shows a fragmentary schematic perspective illustration of a printing hammer lying between the upper and lower row of modules.

The section of the module in the upper row of modules is shown with 80, the one in the lower row with 70. The upper and lower row of modules are spaced apart from one another by spacers 83 running in grooves 82. The course of these spacers corresponds to the column boundaries indicated in FIG. 1 by simple lines. A print hammer is assigned to each column. 7 shows one of these print hammers and is identified by 71. The direction of action of the print hammer is indicated by the arrow D. Details of the print hammers are shown in FIGS. 3A and 3B. These figures show a top view of print hammers lying next to one another in the print hammer bank, in which the anchor webs effective for the drive are offset from one another.

The anchor webs of the pressure hammer 5 are identified by 51, 52, 53 and 54. They are assigned to the working columns, which e.g. are defined by the pole faces 32-1, 32-2, 31-1 and 31-2 (FIG. 2A) of a base plate of the upper row of modules and the pole faces of a corresponding base plate of the lower row of modules aligned with these pole faces. The same applies to the print hammer 6 with the anchor webs 61, 62, 63, 64. These anchor webs are assigned to the pole faces 32-1, 32-2, 31-1, 31-2 of the second column in FIG. 2A. The print hammers 5 and 6 have recesses 55, 56, 66 and 65 to reduce their weight. At their action ends, they are provided with print hammer heads 57 and 67.

The pressure hammers are returned in a conventional manner, e.g. by a leaf spring which engages in a suitable recess 55, 56 or 66, 65. In the above-mentioned recesses or at the ends of the printing hammers opposite the printing hammer heads 57, 67, damping elements for defining the starting position of each printing hammer can also be expediently provided.

Claims (3)

1. Print hammer bank in modular design for electromagnetic print hammer actuators, wherein electromagnetically actuated magnetic operating gaps are defined and a tongue-shaped element (5, 6) (ram, print hammer) is provided which ist movable in the direction of the operating gaps, acting on a print hammer platen (71), and which has armature bars (51-54, 61-64) of magnetizable material, each of which is associated with one operating gap,

wherein the operating gaps of facing pole ends (31-1, 31-2, 32-1, 32-2) are formed by associated electromagnets (30) having a greater width than the tongue-shaped element,

the electromagnets (30) are arranged in a lower (7, 8) and⁼an upper (9, 10) module of the same geometrical shape and design,

the electromagnets (30) for adjacent print hammers within the module are staggered relative to each other in the operating direction of the print hammers, and

the armature bars in the original position of the print hammer in the non-excited state of the electromagnet are external to its operating gaps, being pulled into said gaps upon excitation of the electromagnet,
characterized in that the print hammer bank consists of a lower row (4) of adjacent modules (7, 8) and an upper row (3) of adjacent modules (9-10) of the same geometrical shape and design,

in a plan view of the operating plane of the print hammers, the modules are substantially shaped in the form of a parallelogram having a first and a second side pair arranged in parallel, the first side pair representing the sides of the modules, to which adjacent modules are not applied, and the second side pair representing the sides of the module to which adjacent modules, when arranged in series, are applied, and

the modules in a first module row are arranged adjacent to each other such that the operating direction of the print hammers is orthogonal to the first side pair of a module, and that said sides of all modules within a module row are aligned to each other, extending in parallel to the print hammer platen (71), and that the print hammers in the area of two juxtaposed sides of the second side pair of two adjacent modules are associated therewith in common.

2. Arrangement according to claim 1, characterized in that the electromagnets (30) for each print hammer consist of two U-shaped yokes (31, 32) following, and spaced from, each other, comprising a coil (45) encompassing their adjacent legs (31-1, 32-2).

3. Arrangement according to claim 1, characterized in that each module consists of a base plate (11) facing the print hammer side and an element (12) connected thereto, to which the electromagnet assemblies (30) are molded, and that the base plate has openings for accommodating the pole ends of the yokes of the electromagnet assemblies.

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