JP4199048B2 - Filtration member manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a filtration member in which a plurality of layers of strands are joined together to form a stitch, such as a wound filter such as an air bag inflator filter.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a vehicle is equipped with an airbag device that inflates a bag by instantaneously releasing gas with rapid deceleration due to a collision or the like. The airbag device includes an inflator having a function of instantaneously releasing a gas upon operation thereof, and a bag for inflating and protecting a passenger by the gas released from the inflator. The inflator is configured to filter the gas having a residue at a high temperature generated by the combustion of the gas generating agent together with an igniter and a gas generating agent that generates gas by explosively burning with the heat of the igniter. An air bag inflator filter for cooling is provided as a filtering member. The air bag inflator filter is usually a wound filter in which a deformed wire such as a metal round wire or a square wire (hereinafter referred to as “element wire”) is wound in a plurality of layers and knitted into a tubular body having a stitch. Is adopted. In other words, this wire-wound filter is configured to function as a filtering member when gas passes through a gap between stitches formed by winding the element wire into a cylindrical body.
[0003]
By the way, in this type of wire wound filter, in order to prevent the shape of the stitch from collapsing due to expansion and impact force when gas passes through the stitch, the filtration performance is usually changed by heat treatment (sintering). The overlapping portions of the strands forming the stitches after the strands are wound are joined. In particular, in an air bag inflator filter used as a filtering member in an air bag, a very high temperature gas passes, and thus a strong bonding strength is required. At the same time, when the air bag inflator filter is disposed in the inflator, it is necessary to seal the upper and lower surfaces in contact with the inside of the inflator so that no gas leaks. Therefore, the upper and lower surfaces are compressed in the inflator by compressing the filter in the axial direction. Was in pressure contact. For this reason, the air bag inflator filter is required to have a reaction force equal to or greater than a predetermined value after being compressed in the axial direction, that is, a restoring performance for returning to the original shape.
[0004]
Therefore, recently, in order to improve the joint strength and restoration performance by the required performance of the filter for airbag inflator, the sintering temperature is increased, the sintering time is increased, or the sintering treatment atmosphere is changed. A manufacturing method has been proposed (for example, see Patent Document 1). In Patent Document 1, the restoration rate is calculated as an index representing the restoration performance to return to the original shape when the wire wound filter is compressed in the axial direction, and the restoration rate is equal to or higher than a predetermined value. A linear filter is said to be a suitable product. This restoration rate is required to be 40% or more at least and desirably 50% or more.
[0005]
[Patent Document 1]
JP 2001-171472 A (page 3-5, FIG. 4)
[0006]
[Problems to be solved by the invention]
However, in the manufacturing method of Patent Document 1, in order to obtain a wire wound filter having a restoration rate of a predetermined value or more by changing the restoration rate, the sintering temperature or the sintering time must be changed. For this reason, it takes a lot of labor and time to change the sintering temperature or the sintering time, and the production efficiency of the filter is deteriorated. In some cases, it is necessary to modify equipment such as an electric furnace in accordance with the change of the sintering temperature or the sintering time, and the manufacturing cost is high.
[0007]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a method for manufacturing a filtration member that can easily change the restoration rate.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the invention described in claim 1 is formed into a tubular body having stitches by intersecting strands wound so as to form a plurality of layers, and firing the tubular body. In the method for producing a filtering member for binding , the amount of traverse that is the moving length in the winding width (L) direction per turn of the strand when the strand is wound around a plurality of layers, and the tension associated with the strand And the restoration rate of the filter member is set by the following formula .
F = 85.1-1.75 × P−0.77 × T
However, F: Restoration rate of filtration member, P: Traverse amount (mm), T: Tension (N)
[0009]
Invention of Claim 2 makes it a summary that the tension concerning the said strand satisfies the following formula in the manufacturing method of the filtration member of Claim 1.
5 × R ≦ T ≦ K × A
However, R: Wire diameter (mm), T: Tension (N), K: Tensile strength (N / mm ² ), A: Cross section (mm ² )
Invention of Claim 3 is a manufacturing method of the filtration member of Claim 1 or 2, The traverse amount of the said strand is longer than the maximum width of a strand, and is the axial direction of the said filtration member. The gist is to set it shorter than the length.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is embodied in a method for manufacturing an air bag inflator filter (a type of filtration member) installed in an inflator of an air bag device will be described with reference to FIGS.
[0013]
As shown in FIG. 1, an igniter 11 that performs ignition based on an operation signal from a sensor (not shown) is provided at a central portion of an inflator 10 of an airbag device (not shown) in the present embodiment, and the igniter 11. A flammable auxiliary combustor 12 is provided to assist the generation of heat by ignition. A chamber portion 13 is provided on the outer periphery of the igniter 11 and the auxiliary combustor 12 so that heat generated by the igniter 11 and the auxiliary combustor 12 flows. A gas generating agent 14 is installed in the chamber 13, and the gas generating agent 14 explosively burns by the heat generated by the operation of the igniter 11 and the auxiliary combustion agent 12 to generate a large amount of gas. The gas is supplied together with the inflator 10 to a bag (not shown) provided in the airbag device.
[0014]
Further, a filter 15 that is a filtering member is disposed in the inflator 10 so as to surround the chamber portion 13. The filter 15 functions as a cooling member that cools the high-temperature gas generated by the explosive combustion of the gas generating agent 14 and supplies it to the bag, and filters the residue contained in the gas to the bag. It has a function as a filtration member for supplying gas.
[0015]
As shown in FIG. 2, the filter 15 is formed by winding a deformed wire (hereinafter referred to as “element wire”) 16 such as a metal square wire or a round wire around a cylindrical bobbin (not shown) serving as a shaft member. After forming the stitch, the bobbin is pulled out to create a hollow cylinder. In the present embodiment, as an example, an iron wire material containing iron as a main component is used as an element wire 16, and the element wire 16 is wound around the outer peripheral surface of the bobbin 500 times (the number of turns is 500), and an outer diameter φ60 mm is formed. A winding type filter 15 having a hollow cylindrical shape having an inner diameter of 46 mm and an axial length of 30 mm is illustrated. The strand 16 is a square wire, and has a vertical width of 0.3 mm and a horizontal width of 0.68 mm.
[0016]
Therefore, in this filter 15, when a large amount of high-temperature gas generated by explosive combustion of the gas generating agent 14 passes through the gap between the stitches formed by winding the metal wire 16. In addition, it is possible to cool the gas or filter the residue contained in the gas. Further, as shown in FIG. 2, the winding interval of the strands 16 at the time of winding is the pitch C, the winding angle between the strands 16 intersecting each other to form a stitch is the intersection angle θ, and the bobbin axis of the strand 16 The winding width with respect to the direction is referred to as a winding width L, and a portion where the wires 16 intersecting each other come into contact with each other and overlap is referred to as a contact portion S.
[0017]
Here, a manufacturing method of the filter 15 which is a filtering member will be described. First, a wire 16 such as a metal square wire or a round wire is applied with a predetermined tension, and is wound around the outer peripheral surface of the bobbin by cross winding to form a stitch. As a winding method, one strand 16 is supplied to a delivery guide (not shown), and the delivery guide is reciprocated along the axial direction (winding width L direction) of the rotating bobbin while Wind the wire 16 around the bobbin. At this time, the predetermined tension applied to the strand 16 is set within the range of the following conditional expression (1).
[0018]
5 × R ≦ T ≦ K × A (1)
Where R: wire diameter of the wire 16 (mm), T: tension (N), K: tensile strength of the wire 16 (N / mm ² ), A: cross-sectional area of the wire 16 (mm ² )
Here, the wire diameter of the strand 16 is determined from the cross-sectional area of the strand 16 assuming that the strand 16 is a round wire (note that the wire diameter is the diameter of the round wire). In form, it is approximately 0.5 (mm). Further, the tensile strength of the strand 16 depends on the wire, and in this embodiment, it is 500 (N / mm ² ) because it is an iron wire. When the tension applied to the strand 16 is set outside the range indicated by the conditional expression (1), for example, when the tension applied to the strand 16 is small outside the range indicated by the conditional expression (1), the strand It becomes difficult to wind 16 around the bobbin. Further, for example, when the tension applied to the strand 16 is large outside the range indicated by the conditional expression (1), there is a possibility that the strand 16 is broken.
[0019]
Further, the “movement of the wire 16 (in the winding width L direction)” accompanying the reciprocating movement of the feeding guide tool in the winding width L direction is referred to as “traverse of the strand 16”, and “ The “movement (feed-out length) in the winding width L direction per turn of the wire 16” is referred to as “traverse amount of the wire 16”. In FIG. 2, in the winding width L direction, the distance L1 from the center of a specific strand 16a to the center of the adjacent strand 16b corresponds to the “traverse amount of the strand 16”. By changing the traverse amount of the strand 16, the shape of the stitch is changed, and the filtration performance of the filter 15 is changed. The traverse amount of the strand 16 is set to be longer than the lateral width that is the maximum width of the strand 16 and shorter than the length of the filter 15 in the axial direction in order to form stitches in the filter 15. That is, the traverse amount of the strand 16 in this embodiment is set within the range of 0.68 mm to 30 mm.
[0020]
The stitches of the filter 15 are obtained by calculating optimum values for the pitch C, the winding width L, the crossing angle θ, etc. of the strands 16 by computer simulation, and manufacturing them with the optimum condition values. The winding density and the like can be made as desired, and various stitches can be formed according to the demands for various filtering functions.
[0021]
Next, at the end of winding of the strand 16, the winding end end 17 of the strand 16 is fixed (joined) by welding or the like while the predetermined tension is still applied to the strand 16. Then, a bobbin that is a shaft member is removed to obtain a hollow cylindrical pre-heat treatment filter. Thereafter, when a sintering process is performed in order to join the contact portions S of the strands 16 that intersect in a plurality of layers by winding, a filter 15 as shown in FIG. 2 is manufactured.
[0022]
By the way, when the filter 15 is disposed in the chamber portion 13, the upper and lower surfaces 15a and 15b of the filter 15 need to be pressed against the inner surface 10a of the inflator 10 and sealed, so that the filter 15 has a predetermined height in the axial direction. The ability to return to the original shape after being compressed is required. For this reason, the filter 15 must have a restoration rate equal to or higher than a predetermined value. The restoration rate is the ratio between the amount of change in the axial direction when the filter 15 is compressed in the axial direction and the amount of restoration restored to the original state after compression. For example, when the height of the filter 15 is compressed by about 5% to 7% and the difference in height before and after compression is half of the compressed height, the restoration rate is 50%. This restoration rate is required to be 40% or more at a minimum, and a case where it exceeds 50% is a suitable product.
[0023]
Therefore, according to such a request, in the present embodiment, several conditions are set when the filter 15 is manufactured. Hereinafter, these conditions will be described.
[0024]
FIG. 3 is a graph showing the results of examining the relationship between the restoration rate of the filter 15, the traverse amount when the strand 16 is wound and the tension applied to the strand 16, and the restoration rate of the filter 15. And the traverse amount of the strand 16 when the strand 16 is wound are shown for each tension applied to the strand 16. Specifically, the relationship between the restoration rate of the filter 15 and the traverse amount of the strand 16 when the tension of the strand 16 at the time of winding is 10 N is shown by the solid line 101, and the tension of the strand 16 is 15 N The solid line 102 shows the relationship between the restoration rate of the filter 15 and the traverse amount of the strand 16 in FIG. The solid line 103 shows the relationship between the restoration rate of the filter 15 and the traverse amount of the strand 16 when the tension of the strand 16 is 20N, and the restoration rate of the filter 15 when the tension of the strand 16 is 25N. The solid line 104 shows the relationship between the traverse amount of the wire 16 and the traverse amount of the wire 16. In FIG. 3, solid lines 101 to 104 are based on numerical values obtained when the filter 15 is sintered under predetermined sintering conditions (sintering temperature 1100 ° C., sintering time 30 minutes). This is an approximate line drawn.
[0025]
The following can be understood from FIG. The smaller the amount of traverse of the strand 16 when the strand 16 is wound around the bobbin in a plurality of layers, the greater the restoration rate of the filter 15. That is, it is understood that the traverse amount of the strand 16 from the solid lines 101 to 104 in FIG. 3 is an important factor for determining the restoration rate of the filter 15, and the restoration rate of the filter 15 is adjusted by changing the traverse amount. it can. Further, the smaller the tension applied to the strand 16 when the strand 16 is wound around the bobbin in multiple layers, the greater the restoration rate of the filter 15. That is, the tension applied to the strand 16 from the solid lines 101 to 104 in FIG. 3 is an important factor for determining the restoration rate of the filter 15, and the restoration rate of the filter 15 is adjusted by changing the tension applied to the strand 16. I can understand.
[0026]
Therefore, the following empirical formula (2) was derived from the solid lines 101 to 104 in FIG.
F = 85.1-1.75 × P−0.77 × T (2)
However, F: Restoration rate, P: Traverse amount (mm), T: Tension (N)
Using this empirical formula (2), if the traverse amount of the strand 16 and the tension applied to the strand 16 when the strand 16 is wound are changed, the restoration rate of the filter 15 after the sintering process can be predicted. It becomes possible.
[0027]
Next, since the restoration rate varies depending on the sintering process condition, it is verified whether the empirical formula (2) can be applied within what range the sintering process condition is set. FIG. 4 shows a comparison between the predicted value of the restoration rate obtained by the empirical formula (2) and the actual value of the restoration rate actually obtained by the experiment when the sintering treatment conditions of the filter 15 are changed. For example, in the case (a), the traverse amount of the strand 16 when winding the strand 16 is set to 15.6 mm, the tension applied to the strand 16 is set to 15 N, and the sintering temperature during the sintering process is set to 1100 ° C. When the sintering time is 30 minutes, a comparison between the predicted value of the restoration rate and the actual measurement value is shown.
[0028]
In the case (a) and the case (b), under the conditions that the sintering temperature is 1100 ° C. and the sintering time is 30 minutes, the traverse amount at the time of winding the wire 16 is changed, and the actual value and the predicted value of the restoration rate are changed. Comparing. From the case (a) and the case (b), even if the traverse amount at the time of winding the wire 16 is changed, the predicted value and the actual measurement value obtained from the experimental formula (2) are almost the same under the same sintering treatment conditions. I can understand that they match. Further, when the case (a) and the case (c) are compared, the sintering temperature condition is different, but the predicted value and the actually measured value are almost the same. Therefore, even if the sintering temperature is changed within the range of 1100 ° C. to 1150 ° C., it can be understood that the predicted value and the actually measured value are almost the same. Similarly, when the case (a) and the case (d) are compared, it can be understood that even if the sintering temperature is changed within the range of 950 ° C. to 1100 ° C., the predicted value and the actually measured value almost coincide. Further, when comparing the case (a) and the case (e), it can be understood that the predicted value and the actual measurement value are almost the same even if the sintering time is changed within the range of 30 to 60 minutes. Comparing the case (f), it can be understood that even if the sintering time is changed within a range of 10 to 30 minutes, the predicted value and the actually measured value are almost the same.
[0029]
Therefore, from the cases (a) to (f), if the sintering temperature is set within the range of about 950 ° C. to 1150 ° C. and the sintering time is set within the range of about 10 to 60 minutes, the above empirical formula It can be said that the predicted value of the restoration rate obtained by applying (2) and the actually measured value are almost the same.
[0030]
Since the restoration rate is required to be at least 40%, the tension applied to the strand 16 and the traverse amount of the strand 16 when the strand 16 is wound may satisfy the following conditional expression (3).
[0031]
40 ≦ 85.1-1.75 × P−0.77 × T (3)
However, P: Traverse amount (mm), T: Tension (N)
The traverse amount of the wire 16 and the tension applied to the wire 16 are changed so as to satisfy this conditional expression (3), the sintering temperature is in the range of about 950 ° C. to 1150 ° C., and the sintering time is 10 If the sintering process is performed within a range of about ˜60 minutes, the restoration rate of the filter 15 can be adjusted to a predetermined value (40%) or more.
[0032]
Here, the tension applied to the strand 16 that is an important factor for determining the restoration rate can be set within the range satisfying the conditional expression (1) as described above, but the tension applied to the strand 16 is set to 9 to 15 N. When the value is set within the range, the wire 16 can be most easily wound around the bobbin, and a suitable filter 15 having a well-formed shape is obtained. Further, the traverse amount of the strand 16 that is an important factor for determining the restoration rate can be set within the range of 0.68 mm to 30 mm as described above, but the traverse amount of the strand 16 is within the range of 9 to 14 mm. When set within the range, the shape of the stitch formed by winding the strand 16 is suitable, and the filtration performance is improved. Therefore, when the tension applied to the strand 16 is set within a range of 9 to 15 N so as to satisfy the conditional expression (3) and the traverse amount of the strand 16 is set within a range of 9 mm to 14 mm, the restoration rate is 50%. The above optimal filter 15 was obtained.
[0033]
As described above in detail, the present embodiment has the following features.
(1) When the strand 16 is wound around the bobbin in multiple layers, the tension and traverse amount applied to the strand 16 are changed within a predetermined range so that the filter 15 has a restoration rate equal to or higher than a predetermined value. The restoration rate was adjusted. For this reason, it is possible to easily change the restoration rate and obtain a desired restoration rate without changing the sintering treatment conditions (specifically, the sintering temperature and the sintering time) during the sintering treatment. Therefore, it is possible to save labor and time associated with changing the sintering process conditions, and the manufacturing efficiency of the filter 15 is improved. In addition, even if there is a limit to the sintering temperature that can be set in the sintering furnace, it is possible to adjust the restoration rate of the filter 15, eliminating the need for modification of equipment for the sintering process, and reducing manufacturing costs. can do.
[0034]
(2) When the strand 16 was wound around the bobbin in a plurality of layers, the tension applied to the strand 16 was changed within the range of the conditional expression (1) to adjust the restoration rate. By changing the tension applied to the strand 16 within this range, it is possible to wind the strand 16 around the bobbin easily and without causing a problem while changing the restoration rate.
[0035]
(3) When the strand 16 is wound around the bobbin in a plurality of layers, the traverse amount of the strand 16 is longer than the horizontal width that is the maximum width of the strand 16 and shorter than the axial length of the filter 15. The restoration rate was adjusted as follows. For this reason, it is possible to form stitches on the filter 15 while changing the restoration rate.
[0036]
(4) When changing the traverse amount of the strand 16 and the tension applied to the strand 16 in order to obtain the filter 15 having a restoration rate of 40% or more, the conditional expression (3) is used to change the strand 16 The traverse amount and the tension applied to the strand 16 can be easily selected.
[0037]
(5) The filter 15 was obtained by using the conditional expression (3) by performing the sintering treatment within a temperature range of 950 ° C. to 1150 ° C. and within a time range of 10 minutes to 60 minutes. It is possible to reduce an error between the predicted value of the restoration rate and the actually obtained value of the restoration rate. Accordingly, it is possible to accurately adjust the restoration rate.
[0038]
(6) When the traverse amount of the strand 16 is set within the range of 9 to 14 mm, the shape of the stitch formed by winding the strand 16 is suitable, and the filtration performance is improved. In addition, when the tension applied to the strand 16 is set within the range of 9 to 15 N, the strand 16 can be most easily wound around the bobbin, and a suitable filter 15 having a well-formed shape is obtained. Therefore, the traverse amount of the strand 16 is set within a range of 9 to 14 mm so that the conditional expression (3) is satisfied, and the tension applied to the strand 16 is set within a range of 9 to 15N, thereby 50% An optimum filter 15 having the above restoration rate can be obtained.
[0039]
In addition, the said embodiment can be actualized in another embodiment (another example) as follows.
In the above embodiment, a method for manufacturing a filtration member in which overlapping portions of the strands 16 forming a plurality of layers are joined by a sintering process to form a stitch is shown, but other methods are used instead of the sintering process. May be. For example, as another method, a method of manufacturing a filtration member in which overlapping portions of the strands 16 forming a plurality of layers are joined by high-frequency induction heating to form a stitch may be used. If the contact portion S is joined by high-frequency induction heating, the processing time is shortened and temperature adjustment is facilitated.
[0040]
In the above embodiment, an iron wire material (element cross-sectional area 0.2 mm ² ) containing iron as a main component is used as the element wire 16, the element wire 16 is wound 500 times (number of turns 500), and the inner diameter is 60 mm. A winding type filter 15 having a hollow cylindrical shape with a diameter of 46 mm is formed. However, specifications such as the material (element wire 16) and size of the filter 15 can be appropriately determined according to the shape and size of the inflator 10 to be equipped.
[0041]
In the above embodiment, the traverse amount of the strand 16 and the tension applied to the strand 16 are changed so as to satisfy the conditional expression (3), and the sintering temperature is set within a range of about 950 ° C. to 1150 ° C. However, the sintering temperature may be set outside the range of 950 ° C. to 1150 ° C. if a slight error in the recovery rate is allowed. However, if the sintering temperature is too low, the strands 16 will not be joined, and if the sintering temperature is too high, the ordinary sintering furnace will not be able to withstand the sintering furnace itself, so a range of 950 ° C to 1150 ° C It is not desirable to set the sintering temperature far from the above.
[0042]
In the above embodiment, the traverse amount of the strand 16 and the tension applied to the strand 16 are changed so as to satisfy the conditional expression (3), and the sintering process is performed within a range of 10 to 60 minutes. However, if some error is allowed in the restoration rate, the sintering time may be set outside the range of 10 to 60 minutes. However, if the sintering time is too short, the strands 16 will not be joined, and if the sintering time is too long, the productivity will deteriorate, so set the sintering time far outside the range of 10 to 60 minutes. Is not desirable.
[0043]
A technical idea that can be obtained from the embodiment and the other examples described above will be disclosed.
(B) The method of producing Filtration member you wherein wires with each other are joined by high-frequency induction heating the wire to each other at points of intersection.
[0044]
(B) when winding the wire in a plurality of layers, and set the traverse amount of the wire within the 9Mm～14mm, you and setting the tension on the wires within the 9N~15N method of manufacturing filtration member.
[0045]
(C) The wires are joined by a sintering process performed at a location where the wires intersect each other within a temperature range of 950 ° C. to 1150 ° C. and within a time range of 10 minutes to 60 minutes. method of manufacturing to that filtration member and.
[0046]
【The invention's effect】
As described above in detail, according to the present invention, the restoration rate of the filtration member can be easily changed.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an inflator.
FIG. 2 is a perspective view of a filter.
FIG. 3 is a graph showing the relationship between the restoration rate of a filter, the amount of traverse of the strand when winding the strand, and the tension applied to the strand.
FIG. 4 is an explanatory diagram showing a comparison between a predicted value of a restoration rate and an actual measurement value.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Inflator, 15 ... Filter (filtration member), 16, 16a, 16b ... Elementary wire.

Claims (3)

In the manufacturing method of the filtration member which forms in the cylindrical body which has a stitch by intersecting the strands wound so that it may form a plurality of layers, and sintering this cylindrical body , the above-mentioned strands are made into a plurality of layers When the wire is wound, the traverse amount, which is the moving length in the winding width (L) direction per wire, and the tension related to the wire are adjusted, and the restoration rate of the filter member is set by the following formula. A method for producing a filtration member, characterized in that it is configured as described above.
F = 85.1-1.75 × P−0.77 × T
However, F: Restoration rate of filtration member, P: Traverse amount (mm), T: Tension (N) The manufacturing method of the filtration member according to claim 1, wherein the tension applied to the element wire satisfies the following expression.
5 × R ≦ T ≦ K × A
However, R: Wire diameter (mm), T: Tension (N), K: Tensile strength of wire (N / mm2), A: Cross section of wire (mm2)   The method for manufacturing a filtration member according to claim 1 or 2, wherein the traverse amount of the strand is set to be longer than the maximum width of the strand and shorter than the axial length of the filtration member. .

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