JPS6114915A - Method and device for mounting backer material onto surface of workpiece - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for applying polymeric material to a workpiece.

In many technological endeavors, it is necessary to provide a relatively thin, uniform layer of polymeric material on the surface of a metal sheet. For example, such a need arises when an energy beam, such as an electron beam or a laser beam, is used to perforate a metal sheet. In such applications, the layer of polymeric material is called a hacker (backing), and the polymeric material is applied as a layer of uniform thickness and in close contact with the exit side of the workpiece in which the hole is to be drilled. It must be installed in such a condition. During the drilling process, the workpiece is mounted on a holder and the hacker is clamped between the workpiece and the holder. Several hackers are disclosed in U.S. Pat.

Common titanium and iron based alloy sheets are generally very uniform in thickness. However, these sheets generally have a certain amount of bowing. That is, the sheet does not lie in a flat plane, so if the hacker is an independently extruded layer of material, the hacker and the metal sheet are mounted on the working surface of the perforation holder. Then, the close contact between the hacker and the metal sheet is lost due to the warping of the metal sheet. As a result, hackers will not be able to fully utilize their capabilities.

On the other hand, if the hacker is applied directly to the surface of the metal sheet before it is attached to the workpiece holder, various problems arise in achieving the desired results. Although intimate contact between the workpiece and the hacker is easily achieved, the warp cannot be corrected by applying a uniform layer over the warped workpiece. If there is a warp on the surface of the workpiece, the focus of the energy beam becomes carbonized, which makes it impossible to drill the desired hole. Furthermore, with most polymeric materials, it is difficult to provide a uniform layer on the workpiece, even if the workpiece is completely flat. These difficulties arise due to the flow and curing properties of the rubbers and waxes commonly used in hackers.

One object of the present invention is to provide a method for uniformly protecting hackers on metal sheets. Another object of the present invention is to compensate for irregularities such as warping present in the metal sheet so that the sheet placed on the 517W4 surface of the workpiece holder is accurately positioned for electron beam drilling. and also to compensate for irregularities in the flow and curing properties of polymer hackers.

According to the invention, a metal sheet workpiece is placed on a smooth surface of a fixing device and is drawn tightly to the smooth surface, such as by a vacuum generated in a narrow groove provided in said smooth surface. . A flowable hacker material is then introduced onto the metal sheet, the material is leveled relative to the smooth surface, and then allowed to solidify. Some hacker materials, such as RTV rubber, tend to solidify with a thickness near the center of the sheet that is less than the average thickness. For such materials, the leveling board is configured to slide across the fixture parallel to the smooth surface of the fixture. and in this case a leveling board with a concave lower edge is used so that the silver of the hacker material in the center of the sheet is increased compared to the case with a leveling board with a curved lower edge. be done. Thus, when the hacker material solidifies, the hacker has a uniform thickness.

Although a vacuum is preferred as a means of suctioning the sheet to the flat surface of the fixation device, other means of generating a uniform force may be used. If a vacuum is used, the surface of the fixation device is provided with a seal fitted into a recess, such as an O-ring. If the sheet is bowed, the sheet is placed on the fixation device so that its ribbed portions are raised above the surface of the fixation device in a positive direction. Thus, by applying the hacker material to the convex side of the sheet, the sheet will better conform to the surface of the workpiece holder when a subsequent drilling step is performed.

Preferably, a rail surrounds the locking device and is adapted to assist in clamping the metal sheet against the peripheral seal. After a vacuum is applied in the groove to draw the metal sheet flat against the surface of the fixture, the liquid polymer is directed into the cavity on the sheet at the opening of the rail and allowed to harden. If a leveling board with a curved lower edge is used, the bunker will have a substantially uniform thickness after the sheet is removed from the fixing device. However, depending on the hacker material, capillary action occurs in the rail region, forming a meniscus in that region, which causes the hacker to thicken locally.

This makes it impossible to accurately position the sheet during drilling. To eliminate the effects of such capillary action, a relief is provided around the periphery of the hacker. That is, the hacker is undercut at the edges where it is raised. Preferably, the side edges of the rails are sloped outwardly so that a suitable undercut is formed when the hacker is molded into the fixture. Thus, when a Hacker II-loaded sheet is clamped onto a workpiece holder prior to drilling, the raised portion of the hacker captured between the sheet and the holder is easily compressed and reduced to the average thickness of the hacker. Accordingly, the sheets are positioned uniformly. In general terms, according to the invention, by providing a relief in the hacker when forming the hacker or by providing a relief in the workpiece holder, the workpiece for electron beam drilling is formed around the periphery of the hacker. A relief is provided between the holder and the sheet. Accurate hackers are readily obtained in accordance with the present invention; for example, RTV silicone rubber hackers formed in accordance with the present invention and having a thickness of about 2.54+U+ can be used to accurately cut workpieces with an accuracy of about ±0.11- or better. spaced uniformly from the holder.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention will be explained in detail below by way of example embodiments with reference to the accompanying figures.

The present invention will now be described with reference to a silicone rubber hacker that is applied to a titanium sheet metal panel when the sheet metal panel is electron beam perforated by wrapping the titanium sheet metal panel around a drum-shaped workpiece holder. As will be appreciated, the invention is also useful with other workpieces and workpiece holders. The invention is also suitable for applications other than electron beam drilling where a thin layer of polymer must be uniformly applied to an uneven sheet. The present invention may be used to camouflage hackers of a second composition, such as those described in US Pat. No. 4,239,954.

FIG. 1 shows how a hacker uses an electron beam to make a hole. The drum-shaped workpiece holder 20 is a substantially hollow cylinder with a precise outer circumferential surface 22.
A metal sheet 24 as a work piece is clamped to the outer circumferential surface by drawing its ends together. A hacker 26 is located between the metal sheet 24 and the workpiece holder 20. Drilling of the hole 27 is effected by a flow of electrons in the form of a beam 28 emitted by an electron gun 30 and directed into the workpiece, ie the metal sheet 24, through the hole 31 between the protective shields 32. The outer circumferential surface 22 of the workpiece holder 20 is precisely positioned at a distance from the electron gun 30 (typically, the plane of the lower surface of the protective shield 32 is used as a reference plane for such positioning). In order to accurately position the metal sheet 24 with respect to the electron gun 30, the metal sheet 24 must be spaced a certain distance E from the outer peripheral surface 22 of the workpiece holder 20. If the metal sheet is tightly clamped around the workpiece holder, the distance E is determined by the flexibility of the metal sheet and various characteristics of the hacker 26. The present invention relates to the manufacture of such a hacker and to a method of clamping a metal sheet to a workpiece holder.

FIG. 2 shows a sheet 34 having a length of about 1450 mm, a width of about 46 cm, and a thickness of about Q, 5a+s, and an apparatus of the invention for receiving the sheet 34 to be fitted with a hacker. . The device of the invention includes a base 36 having rails 38 and 40 around its periphery.

Seat 34 fits within a cavity defined by rails 38 and 40 and is attached to a smooth upper surface 42 of base 36.
is placed on top. The upper surface 42 of the base 36 has a pattern of relatively narrow interconnected grooves 44. FIG. 3 is a partial cross-section of the device of the present invention showing details as to how the seat engages the rail and base. The seat extends over the top surface 42 of the base and straddles a narrow groove 44.

The rail 38 captures the edge of the sheet and moves the edge into a peripheral O
It is pressed against the ring seal 46. The seat and base thus define a sealed cavity with groove 44 and at one or more locations accessible via boat 48.

Thus, when a vacuum pump, not shown, is connected to port 48, the seat is pulled tightly against the base. Of course, the width of the groove is kept to a minimum to resist curving the sheet too much downwardly into the groove.

To attach the hacker to the seat, use rail 38.4.
0 and the upper surface 51 of the sheet into which the packer material 49 is poured.
The vacuum within 4 is maintained.

One preferred hacker material is Qenoral, Waterford, New York, USA.
RT sold by E 1 electric Co.
It is a silicone rubber that hardens at room temperature, such as V-630. The semi-liquid RTV rubber is leveled by moving a leveling board 50 across the top surface of the rail 38. The leveling board 50 shown in FIG. 2 has guide tabs 52 which engage the outer edges of the rails 38 to provide lateral positioning of the leveling board. Further, the leveling board 50 is provided with a protrusion 54 that extends along the moving direction of the leveling board, so that when the leveling board moves along the longitudinal direction of the base 36, the rubber is attached to the leveling board. It moves in a direction perpendicular to the direction of movement of the device and acts to prevent leakage from the sides of the device of the present invention.

One importance lies in the design of the rails 38 and leveling board 50. FIG. 4 shows the cross-sectional shape of the hacker 56 obtained when a leveling board with a straight lower edge and a rail 58 with a rectangular cross section are used.

A dashed line 60 indicates the cross-sectional shape of the rubber immediately after it is leveled in a semi-liquid state. This is because RTV-630 rubber does not substantially shrink. On the other hand, length line 62 somewhat exaggerates the actual cross-sectional shape of the rubber after it has hardened. From FIG. 4, the rubber becomes thinner in the central part 64 near the center of the sheet 34, and the rubber becomes thinner in the raised part 64 at the peripheral edge near the rail.
6.

The reason why the rubber becomes thinner in the center is not fully understood, but although RTV-630 rubber has a self-leveling property, it is thought that some kind of flow phenomenon is involved. Conceivable. The increased thickness at the periphery is believed to be due to the capillary action of the rubber against the rail 58.

The hacker thus formed is not useful with respect to drilling precise holes in the sheet 34. When such a sheet is mounted under tight tension around a workpiece holder, the thinner thickness of the hacker at the center portion 64 results in uneven bunker thickness along the length of the holder. , the thickness of the hacker is raised at the thicker periphery 66.

In FIG. 2, when carrying out the method of the present invention, the lower edge 68 of the leveling board 50 has a curvature R;
It is raised at a distance S at its center. We have found that for the RTV rubber 2.511 thick hacker described above, the distance S should be approximately 0.461111. The shape and distance S of the leveling board may be varied depending on the thickness of the hacker and the type of material.

FIG. 3 shows the upper surface 60a of uncured rubber and the upper surface 62a after the rubber is cured when a leveling board with a curved lower edge is used.

In this case as well, capillary action occurs at the outer periphery 68 of the hacker. However, the rail 38 is shaped to eliminate the adverse effects of such capillary action. That is, as shown in FIGS. 3 and 5, the rail 38 is provided with an inner edge 70 that forms an angle B with respect to an imaginary plane perpendicular to the upper surface 42 of the base 36. As shown in FIGS. An angle B of approximately 45° has been found to be sufficient, and angles between 30 and 60° are at least as effective. As shown in FIG. 5, the sloped inner edge 70 of the rail 38 need only extend over a portion of the vertical edge of the rail, so that a vertical portion 72 may remain.

FIG. 6 is an enlarged partial view of the main part of FIG. It shows how useful it is in terms of placement. The shape of the hacker 26 is shown in dash-dotted lines 74 before the sheet 24 of the hacker 26 is drawn tightly against the workpiece holder 20. The solid line 76 shows the deflection of the hacker against the top surface 22 of the holder 20 when the sheet is wrapped tightly around the holder. The relief provided by the sloped inner edge of the rail between the hacker and the sheet prevents the raised edge 68 of the hacker from deforming the outer edge of the sheet 24 radially outward.

FIG. 7 shows another embodiment of the invention. The hacker 268 has an undercut or relief 78 provided by a rail having a stepped edge as opposed to a sloped inner edge. Although a sloped inner edge is preferred, the invention may be practiced with the embodiments described above and with other embodiments. The general form of this aspect of the invention is that the average thickness of the hacker is such that it is flexible at its edges when compressed between the sheet and the workpiece holder. The goal is to reduce the thickness of the hacker edge.

Of course, it is also possible to first form the hacker using a rectangular cross-section rail and then trim the edges of the hacker at the angle formed or remove excess material. However, due to the slight overlap of the rails on the seat, the effective width of the hacker is reduced in such an approach due to the need to create a sufficient vacuum seal on the fixation device.

Therefore, the method described above is less efficient than the previous embodiments in that the area of the sheet that can be perforated is reduced.

It is generally desirable that the rails 40, which receive the longitudinal ends of the sheets, be sloped as well. However, since there is actually a somewhat greater degree of freedom at the longitudinal ends of the sheet, trimming may be employed.

Typically, the ends of the sheet are drilled with holes for engaging clamps that pull the ends of the sheet together and tension the sheet around the workpiece holder.

In use of the apparatus of the present invention, the rail is clamped onto the sheet and the interior of the groove is then evacuated to approximately 7 kPa to create a pressure differential sufficient to pull the sheet flat. The silicone rubber is mixed with the catalyst by mechanical stirring and then vacuum degassed for about 15 minutes to remove any air trapped inside the rubber. After the rubber is poured between the rails and leveled, the rubber is cured in air for about 16 hours. The sheet with the hacker formed by partial curing is removed from the fixing device and cured in an oven at about 100° C. for 1 hour, thereby making it ready for use. Applying a mold release agent on the rail is not necessary, but may be used if desired. Of course, the sheet is carefully sanded and cleaned prior to attaching the hacker to the sheet to facilitate adhesion of the hacker to it.

The manner in which the sheet is placed on top of the base is important. In general, sheets tend to be biased into a warped condition.

That is, the sheet is raised more relative to its general plane in one direction than in the other direction. The sheet must be secured to the top surface so that its bow is in a positive direction relative to the top surface of the base. This is shown in FIG. 8, where a cavity 82 is formed between the seat 84 and the upper surface 42 of the base 36 by the forward displacement of the ridge 80. By attaching the sheet in this manner, the sheet is more easily pulled flat. However, when the sheet is installed in the workpiece holder, the ridges are displaced in a negative direction relative to the holder, and the resisting force of the hacker causes the sheet to be returned to a position a desired distance E from the holder in a positive direction. is even more important.

We used a differential pressure generated by atmospheric pressure in combination with a vacuum. Other differential pressures may be used.

Also, if the sheet is magnetic, magnetic attraction may be used instead of differential pressure. In that case, there is no need for the upper surface of the fixing device to be provided with a groove. Other mechanical or electrical means compatible with the requirements of the invention may be used so that a uniform force is applied to the sheet to press it against the fixing device.

Although the polymer herein is RTV silicone rubber, other polymers such as waxes and various other materials may be used in the practice of the present invention. These materials must be flowable in the sense that they have a sufficiently low viscosity that they form a uniform layer parallel to the surface of the fixation device. The materials also solidify by cross-bonding (curing) or other mechanisms so that the sheet can be removed from the fixture with a layer of sufficient viscosity to retain its shape during handling and electron beam drilling. It must be possible. Thus, if the nature of the hacker is such that it forms a layer of uniform thickness on the surface of the sheet in its flowable state, a leveling board with a curved lower edge may not be used. The method of the invention may be carried out in the following manner.

If a hacker is used that cures more quickly than RTV rubber, and if manufacturing warranties are required,
Rather than using batch-type methods and fixing devices as described above, the bunkers may be applied continuously as long sheets. If such continuous II loading is carried out, the hacker solidifies rapidly and the sheet is sucked onto a flat surface or onto the outer circumference of a smooth cylindrical drum. A hacker is formed by appropriately positioned leveling boards and edge moldings. Thus, although the preferred embodiment of the invention has been described in the context of a fixation device having a smooth, planar surface, the surface of the fixation device need not be planar in practicing the method of the invention. The surface of the fixing device need only be smooth so that warping of the sheet is eliminated by applying pressure to the sheet and the leveling boards are spaced apart at a distance defined by the surface of the sheet. Another somewhat different embodiment of the invention useful is shown in FIG. A rail with straight sides is used to form the periphery of the hacker 26b, thus forming a raised portion 86 at the periphery of the hacker. The smooth outer surface 90 of the holder 20b has grooves 8 extending in the circumferential direction.
It has 8. Sheet 2 with hacker 26b glued
4b is positioned such that the raised edge 86 is positioned 111 within the groove 88. Thus, the relief at the periphery of the sheet in this embodiment of the invention is provided in the holder rather than in the hacker itself. However, this embodiment has the disadvantage that the sheet must be precisely positioned on the workpiece holder, and different workpiece holders must be used for sheets of different widths.

Although the present invention has been described above in detail with reference to several embodiments, the present invention is not limited to such embodiments, and various embodiments are possible within the scope of the present invention. will be clear to those skilled in the art.

[Brief explanation of drawings]

FIG. 1 is a side view of the main parts of an electron beam apparatus showing how a workpiece clamped around a drum-shaped workpiece holder is perforated by an electron beam. FIG. 2 is a previous perspective view of the apparatus of the present invention showing how the sheet is received and how the leveling board is moved along the length of the fixture. FIG. 3 is an enlarged partial cross-sectional view of a portion of the fixation device shown in FIG. 2, showing the grooves in the surface of the fixation device, the sloped sight rails, and the polymer hacker material after curing; It shows. FIG. 4 is an enlarged partial cross-sectional view similar to FIG. 3, illustrating the problem solved by the curved lower edge leveling board and angled rail of the present invention. FIG. 5 is an enlarged partial cross-sectional view of one embodiment of an inclined sight rail. FIG. 6 is an enlarged partial sectional view showing a hacker caught in the darkness between the workpiece holder and workpiece shown in FIG. 1;
Showing the benefits of the beveled edges of the hacker. FIG. 7 is an enlarged partial sectional view similar to FIG. 6 showing another embodiment of a relief provided at the edge of the hacker. FIG. 8 is an enlarged partial cross-sectional view similar to FIGS. 3 and 4 showing how the metal sheet is positioned in the fixation device with respect to warpage of the metal sheet. FIG. 9 shows another embodiment of the invention in which the workpiece holder is constructed to have a recess at its periphery for receiving a hacker formed by a fixing device having a rectangular cross-section rail. ! FIG. 8 is an enlarged partial cross-sectional view similar to U and FIG. 7; 20... Work piece holder, 22... Outer peripheral surface, 24...
...metal sheet, 2G...hacker, 27...hole,
28...dome, 30...electron gun, 31...hole,
32...Protective shield, 34... Sheet, 36...
・Base (fixing device), 38.40...Rail, 42
...Top surface, 44...groove. 46...0 ring seal, 48...boat, 49.
...I (Tsuka-Material, 50...Level 1 Nongbo-1:
, 52... Guide tab, 54... Protrusion, 56...
l (Tsuka-158...Rail, 64...Central part, 6
6... Raised portion (periphery), 68... Lower edge,
70...Inner edge portion, 72...Vertical portion, 78...
Escape, 80... Iron part, 82... Cavity, 84.
... Sheet, 86... Raised portion, 88... Groove,
90...Outer peripheral surface patent applicant United Chiknorrhosis Corporation

Claims (2)

[Claims] (1) A method of applying a hacker material to the surface of a metal sheet workpiece having a ridged surface, whereby the warped region of the sheet is displaced from the smooth surface of a fixing device, thereby placing the first side of the sheet on the smooth surface of the fixation device such that the first side of the sheet cooperates with the surface to define a cavity; The first side of the sheet is attached to the fixation device by creating a vacuum between the side of the sheet and the surface of the fixation device and allowing atmospheric pressure to act on a second side of the sheet. applying pressure against the surface; directing a liquid polymer to the second side of the sheet and at least partially curing the polymer so that the polymer adheres to the sheet; The shape of the portion of the device that abuts the outer periphery of the polymer creates an escape space around the outer periphery of the cured polymer where the polymer adheres to the sheet, so as to uniformize the thickness of the cured polymer. A method comprising the steps of directing a greater amount of uncured polymer to the center of the sheet than to the periphery of the sheet, and releasing the vacuum and removing the sheet from the securing device. (2) A device for adhering a uniform layer of solidified material, such as an electron beam perforation hacker, to the surface of a warped sheet and having a smooth surface with grooves configured to receive the sheet. a fixing device; means for connecting the groove to a vacuum source; and a means for applying a vacuum between the sheet and the surface so that the peripheral edge of the sheet is pressed against the surface by the vacuum. means for sealing against the fixing device for forming a cavity above the surface of the sheet mounted on the fixing device into which a flowable material that is solidified and adhered to the sheet as a layer is introduced; rails removably attached to the surface of the device and surrounding the periphery of the fixing device in which the sheet is received, at least one rail surrounding the periphery of the ply in a direction transverse to the ply; a rail having an edge forming a relief in the layer such that the overall amount of material is less than the average amount of material in the remainder of the layer; and a flow disposed between the rails. a leveling board guided by said rail for possible polymer leveling, said leveling board having a concavely curved leveling surface facing said surface of said fixation device.