DE2112221A1 - Fastening insert - Google Patents

Description

TOOL RESEARCH & ENGINEERING CORPORATION, 9460 Wilshire Boulevard, Beverly Hills, California (V. St. A.)

Fastening insert

The invention relates to a fastening insert for honeycomb sandwich panels with thin cover sheets or plates, the fastening insert for connecting components or for connecting two or several honeycomb cell panels is used.

In the case of panels of the honeycomb sandwich type, up to now essentially conventional fastening devices have been used, such as B. screws, bolts or rivets are used. Usually were in the to be fastened Honeycomb cell plates holes provided and a screw, a rivet or screw bolt was inserted through the hole and in a known manner (e.g. with Retaining nuts or rivets). Honeycomb cell panels usually have very thin cover sheets or plates (e.g. less than 0.0508 cm) that can be seriously damaged if the fasteners are used must be repeatedly attached and removed, or when the fasteners are tightened or clamped to another component

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Must · You can do that with most known fasteners do not have head sizes or shapes that adequately distribute the shear, compressive and tensile loads in all directions over an area, which is large enough to prevent the thin cover sheets or layers from being deformed and / or damaged in the fastening area Tried of inserts to protect the honeycomb sandwich panels, but these inserts only passed made of cylindrical sleeves which were installed using a tight tolerance press fit, and could the Do not distribute the mechanical stresses caused by the fasteners to a significant extent These known inserts and their attachment increased manufacturing costs because of the tightness required Tolerances for a secure interference fit · Except for the interference fit, the known inserts had no positive fastening in the plate · The configuration of the known ones Inserts also did not ensure that the various mechanical Stresses evenly in all directions over a larger surface section of the cover sheets or layers were distributed.

The present invention recalls the foregoing disadvantages and problems described by proposing a unique but simple fastening insert, which can be easily and simply used in different types of honeycomb construction panels. The fastening device according to the invention can be fastened in a form-fitting manner and has a configuration through which reduce the mechanical stresses on the fasteners over a relatively large surface area

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be divided, whereby the thin cover sheets of the panels from damage as a result of repeated fastening and Removal of fasteners and protected as a result of tightening fasteners

The fastening insert according to the invention for honeycomb sandwich panels is characterized by an upper part with a relatively flat top and a sloping inner side such that the thickness of the upper part in Decreasing towards its Utafangskante and with a first central opening; one into an integral unit body portion connected to the upper part of substantially cylindrical, a second coaxial to the first opening-aligned opening-having configuration, an annular groove extending at a distance from its outside is provided on its bottom surface; and one of outer part of the body portion and the annular groove formed lip part, which extends beyond the bottom surface of the body portion and so an unbending of the lip to the outside and forms a fastening mechanism that acts between the insert and the honeycomb cell sandwich panel

According to the invention, a metallic insert is proposed which is made of a material such as corrosion-resistant steel, various nickel alloys or titanium alloys. The new insert has a relatively large flat top, which makes the Cover plate before the often as a result of repeated attachment and removal of the fastening means and as a result of strong Tightening the fastener caused damage protects. The top of the insert is generally generally circular with a suitable opening

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for a fastener, the inner surface of the top of the insert, which rests on the cover plate, is slightly inclined to the different, from the Forces acting on the fastening elements caused mechanical stresses uniformly in to initiate a larger area · The angle of the inner surface of the top is preferably relatively shallow (about 8 to 15 °) held, the thickness of the upper part decreases in the direction of the outer circumference. the The opening provided in the top is usually | fi a countersunk opening (e.g. 100 °) to accommodate the different Types of standard fastening elements with conical heads.

The top of the insert described above forms an integral unit with a body portion which is substantially cylindrical in shape. The outer and lower portions of the body portion are in the form of a lip protruding from the lower surface of the inner portion of the body portion. · Ize after insertion of the insert into a suitable opening, the lip is bent to the outside, the cell plate to a positive connection for fastening the insert in the honeycomb "To create the ^G and the dimensions of the top portion and body portion are of about the size of the fastening element used and the thickness of the building board.

Certain types of honeycomb panels may have "full thickness" and "compressed areas". "Full thickness" areas are those portions in which

The thickness of the building board is equal to the height of the honeycomb cells plus the thickness of the two cover sheets. "To-

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Compressed Areas "become the sections of the Plates called where the areas have been compressed to form a closed or full strength The honeycomb cell panels manufactured by Tool Research and Engineering Corporation and sold under the trademark "Stresskin" can be used for connection with other "Stresskin" honeycomb panels or for attaching the panels to other structural members are pressed together to form suitable compressed areas to create·

The insert according to the invention can be used in honeycomb panels that only have areas of full thickness but can also be applied to panels with areas of full thickness and areas of compression The size of the insert body will vary depending on the thickness of the plate and depending on whether it is in an area full strength or a compressed area: the plate is used to change.

The thickness and length of the lip is also determined by the thickness of the plate. On the other hand, the dimensions of the lip are also dependent on the material used for the insert. The lip must preferably be able to be bent outwards with sufficient hatred _so that it engages one of the cover plates and is positively connected to it.

The sloping portion of the top of the insert and the outwardly unflexed lip of the body portion of the insert are used to secure the insert in the plate. The body portion of the insert

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acts as a protective sleeve or guide for the fastening element. The top of the stake and- in lesser ones Dimensions - the outwardly bent surface serves as a protective surface for the cover sheet of the plate in the area of the fastening element and at the same time distribute the shear, compression and tensile loads evenly in all directions · It has been found that the shallow angle of the inner contact surface has excellent properties in terms of load distribution on the top of the Insert, where usually the head of the fastening

| L element is arranged, has the consequence · Hit angles

on the order of 8 to 15 ° to the horizontal, satisfactory results have been obtained · Is preferred an angle of 10 ° to the horizontal is used · The lower section of the insert according to the invention is used after bending the lip outwards also to form a protective surface for the other cover sheet Because of the positive or form-fitting fastening of the insert, the size tolerances of the openings to accommodate the inserts in the panels in a range of approximately 0.0127 mm to 0.0508 am (0.0005 to 0.002 Xnch). This is considerably larger than the narrower ToIe- required for a press fit

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The invention is described in the following description of an embodiment in conjunction with the drawing explained in more detail, namely shows:

Flg. 1 shows a plan view of the fastening insert according to the invention;

FIG. 2 is a sectional view taken along line 2-2 in FIG

Fig. 1, wherein in dash-dotted lines a Plate and the manner in which the lip of the inventive mounting insert engages the plate is shown;

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3 is a sectional view of a honeycomb cell panel full strength in which an insert according to the invention is attached; and

Fig. 4 is a sectional view of a compressed area of a honeycomb cell panel in which the insert according to the invention is attached

The fastening insert 10 has a design which protects the cover sheets of a honeycomb cell sandwich panel. Oa a honeycomb cell plate commonly referred to as but slightly _e s is used component solid is · commonly manufactured with very thin cover sheets TJM to prevent caused by the use of fasteners damage to these flünnen cover sheets, it is necessary to provide a component which the mechanical stresses (e.g. shear, compression and tensile loads) distributed. These stresses are usually concentrated in the honeycomb cell material in the gab iets, where fastening elements are used to fasten the honeycomb cell panel to other components or to fasten various honeycomb cell panels to one another.

The inserts 10 can be made from any for the required If necessary, suitable material must be manufactured. It it has been found that corrosion-resistant steel, Nickel alloys (see B® Inconel), aluminum and titanium Preferred® materials are for use according to the invention.

In Figs. 1 and 2, a preferred embodiment of the fastener insert of the invention is illustrated. The insert 10 consists of three main sections, namely the upper part 12, the body section 14 and the lip 16. The upper part 12 has a relatively flat circular

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Fönnige top 12a and an obliquely inclined or conical inside 12b The inside 12b serves as a contact or work surface for the insert 10 and the Cover plate of the plate in which the insert is attached. The thickness of the upper part 12 gradually decreases in the direction of its outer utafang edge 18. At the university edge 18, the sides 12a and 12b have their smallest distance from each other · The angle or the The conicity of the inner contact surface 12b relative to a horizontal plane is denoted by "D" in FIG. "D" can vary depending on the material used for the insert and the material of the honeycomb cell panel · However, it has been found that excellent results in terms of the distribution of mechanical stresses can be achieved if "D" is relatively flat and with most metallic honeycomb cell panels (e.g. made of corrosion-resistant steel, various nickel alloys and titanium alloys) in the range of about 8 to 15 °.

The upper part 12 has an opening 20 for receiving a suitable fastening element. The opening 20 is usually a countersunk opening (for example 100 ° countersinking) which, depending on the head of the fastening element, extends into the body section 14 can·

The body portion 14 forms an integral unit with the upper part 12. The portion 14 is in the form of a substantially hollow cylinder which is coaxially aligned with the upper circular section 12 The opening 22 running through the entire length of the body section 14 is in connection with the opening 20, and both openings are in coaxial alignment.

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The openings 20 and 22 are made in such dimensions that they can receive a corresponding fastener, so that the opening 20 has a configuration which largely corresponds to the shape of the mounting head, while the opening 22 is shaped so that it largely corresponds to the shape of the Corresponds to the shaft part of the fastening element. A recess or annular groove 24 is provided in the body section 14, which is located in the vicinity of the lip 16. The lip 16 is an integral part of the body portion 14 and is partially formed by the annular groove 24. The lip 16 projects above the bottom surface 26 of the body portion 14 so that sufficient lip material is available which can be bent outwards so that it comes to rest against a surface of a suitable plate and forms a form-fitting attachment. The thickness of the lip 16 and the depth and width of the annular groove 24 are ize of the lip 16 for positively fastening the insert in the plate for the required circular area on the type of material used for the insert 10 and the desired ^G depending · The in Fig The dashed lines shown in FIG. 2 show a typical plate into which the insert according to the invention is inserted, and the figure further shows how the lip 16 is bent outwards so that it rests against the underside of the plate and engages around it, whereby the insert in FIG the plate is held.

The different dimensions of the insert vary depending on the type of material used for the insert and on the type of material and the Thickness of the plate in which the insert according to the invention is used·

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On the basis of various tests and calculations, it was found that the size ratios given below (see FIG. 2) lead to excellent results in the case of metallic honeycomb cell panels (e.g. made of corrosion-resistant steel, made of nickel alloys and made of titanium alloys) lead to:

A / B - 1.7 to 2.0

A / C - 1.6 to 1.85

D - 8 ° to 15 °

E / F »0.3 to 0.7

- G / H »0.5

B / J - 1.52 - 0.2

Here t mean

A »diameter of the flat circular top 12a;

B »largest diameter of the countersunk opening 20; C s diameter of the outer surface of body portion 14; D m from inner surface 12b and one parallel

to the top 12a extending horizontal. Plane formed angle;

"E" dimension of the thickness of the lip 16;

F »width of the annular groove 24; 6, - height of the lip 16; H »depth of the annular groove 24; J «narrowest diameter of the countersunk opening 20 ·

For example, various inserts have been made for use in honeycomb panels made of corrosion-resistant Steel, nickel alloys, and titanium alloys with faceplate thicknesses of 0.508 mm (0.02 inches) or less

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304 CRES manufactured. These inserts led to excellent results with regard to the mechanical stresses caused by the connection of Ar honeycomb cell panels with other honeycomb cell panels or with Forces applied to other components are caused in the fastening elements · The mentioned single seats made of 304 CRES when used in panels with honeycomb link core heights of about 0.635 cm to 5.08 cm Co, 25 inches to 2.0 inches) and cover sheet thicknesses of about 0.2032 in to 0.508 mn (0.008 to 0.02 inch) the following « Parameter:

AWAY A / C D. E / P G / H B / J Mission I 1.83 1.73 10 ° 0.6 0.6 1.51 Mission II 1.77 1.73 10 ° 0.5 1.0 1.52 MissionIII 1.90 1.81 10 ° 0.3 2.0 1.53

Referring now to Figures 3 and 4, there is one fastener insert in accordance with the present invention in one "full strength" area and one As already mentioned above, certain honeycomb cell constructions, such as the "Stresskin" panels from Tool Research and Engineering Corporation can be connected at one end by pressing the honeycomb cell panel together without the bond between the honeycomb cell core and the cover sheets is adversely affected

Fig. 3 shows an insert 10 according to the invention, in one

Area 30 full strength of a honeycomb cell panel inserted · Fig. 4 shows one in a compressed The insert 10 according to the invention is used in area 32 of a honeycomb cell panel. In both figures, the insert is

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inserted and secured in the same way. The honeycomb cell panel shown in FIGS. 3 and 4 can at 30 'and 32 · initially at an angle that is slightly smaller than the angle D, be countersunk in order to facilitate the bending of the lip 16. If no previous countersinking must be applied during bending or flanging the lip 16 is greater Force to be applied

Bending or UfrJbSrdeln the lip 16 can be done on | fc known catfish are made Cz. B * dureli Börde! Tools).

The compressed area configuration shown in FIGS. ₉ and 4 is used where two honeycomb central panels are to be connected to one another, the depth of which when connected should not be greater than the depth of a single panel two plates, the kit · each eiRssis insert according to the invention in each plate or a single insert passed through the pressed flat surfaces of both plates, with a further construction. or attached to it by juxtaposing the panels and securing them with a suitable fastener. It will be apparent that the height of the full thickness areas on either side of the fastener can be kept substantially the same, according to the experience the ssusarase-pressed areas uses wJj? "ä _e The press-pressed oemets of the plates are particularly firm and can absorb larger beasasprushustgs than before without damage.

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The invention thus allows the use of standard fastening elements in connection with honeycomb cell panels with thin cover sheets, without that earlier Unavoidable problems of deformation and damage occur · The between the holes in the plate and the diameter of the body portion 14 required tolerances (e.g. 0.0127 to 0.0508 mm) are relatively large and can be compared to the required closer tolerances in the known, introduced with a press fit constructions under considerable Time and labor savings can be applied · The design of the upper section 12 of the insert 10, the lip 16 and the annular groove 24 means that the fastening elements caused mechanical stresses evenly distributed over a relatively large surface area. the Distribution of mechanical stresses and physical protection against damage to the cover plate through the fastener make the invention Use as a particularly useful component in the growing field of application of honeycomb cell structures. The relatively large tolerance range for the insertion of the inserts and the form fit are wide, new features not used in the known components and / or processes.

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Claims (1)

Claims sasBssBsasssasai IlJ fastening insert for honeycomb sandwich panels, characterized by an upper part (12) with a relatively flat upper side (12a) and one such inclined extending inside (12b) that the thickness of the upper part decreases in the direction of its peripheral edge (18), and having a first opening (20) arranged on a horse; a body portion (14) of substantially cylindrical configuration having a second opening (22) oriented coaxially to the first opening (20), an annular groove (24) extending at a distance from its outside is provided on its bottom surface (26) is; and one formed by the outer part of the body portion (14) and the annular groove (24) Lip portion (16) extending beyond the bottom surface (26) of the body portion (14) and so a the lip (16) can be bent outwards and one between the insert (10) and the honeycomb sandwich panel (30, 32) forms acting fastening device. 2. Fastening insert according to claim 1, characterized in that that the top (12a) of the upper part (12) is circular. 3. Fastening insert according to claim 1 or 2, characterized in that the first opening (20) is a countersunk opening to accommodate fastening elements with tapered Heads is trained. BATH ORIGINAL 109850/10 11 4. Fastening insert according to one of claims 1 to 3, characterized in that the inside (12b) of the upper part (12) at an angle of about 8 ° to 15 ° Horizontal runs S ₉ fastening side according to one of claims 1 to 3, characterized in that the inside (12b) of the upper part (12) runs at an angle of 10 ° over the horizon "tal @ n" sfestigisngseinsats nacla one of claims 1 to 5, that the ratio (A / B) of the (A) the upper side (12a) to the largest (B) one countersunk opening C 20) ii »area of I ₉ I is up to 2.0 © Fortification ice safes n & ch eifaes? of claims 1 to 6, !! g <§ identifier & @ fc ₉ that the ratio (A / C) of the (A) the @benesi top side C 12a) sram outer diameter (C) of the body section (14) in the range from about 1.6 to 1.85. 8. Fastening insert according to one of claims 1 to 7, characterized in that the ratio (E / F) of the thickness (E) of the lip (16) to the width (F) of the annular groove (24) te range from about 0 _? 3 öis 0.7. S «. Bafestigimgsednsats according einans of claims 1 to 8, ^ adus-ch in _s that the ratio (G / H) represents the height of the lip (15) is ungegleich to Tief® (H) of the annular groove (24) or gr5ßer than o, 5 » , em ö © r claims 1 to 9, gekennseie! m © t _s "let the VerhHlfeais (B / J) of the mirchsiesssM's CB) usm AnseäkSffteung (20) below their era's Ourtihnaesses' CJ ^ feel about 1, S2 is. 10 8 8 5 0/1011 11 · Fastening insert according to one of the preceding Claims, characterized in that the fastening insert (10) is made of metal * BATH ORIGINAL 109850/1011