US3678738A - Test device for trim assemblies - Google Patents

Abstract

A hand-operated test device for nondestructively determining the bond strength between individual layers of a fabricated trim assembly having substantially parallel bond lines formed thereon. The test device includes a pair of overlapping arms pivotally interconnected in a scissors fashion and having each arm formed at one end with a probe section and at the other end with a handle. One arm is provided with a leaf spring and gauge so that upon insertion of the probe end of the test device into a pocket located between the bond lines, a squeezing action applied to the handles results in a movement of one handle relative to the other of an amount indicated by the gauge so as to provide a reading of the bond strength between the individual layers of the trim assembly.

Description

United States Patent Jubelt [54] TEST DEVICE FOR TRIM ASSEMBLIES Warren L. Jubelt, East Detroit, Mich.

General Motors Corporation, Detroit, Mich.

221 Filed: Aug. 6, 1970 21 Appl.No.: 61,682

[ 72] Inventor:

[73] Assignee:

s2 U.S.Cl..... ..73/88 B, 73/141 A 2,406,386 8/1946 Koepnicketal ..73/88 [451 July 25, 1972 Attorney-J. L. Carpenter and E. J. Biskup [5 7] ABSTRACT A hand-operated test device for nondestructively determining the bond strength between individual layers of a fabricated trim assembly having substantially parallel bond lines formed thereon. The test device includes a pair of overlapping arms pivotally interconnected in a scissors fiashion and having each arm formed at one end with a probe section and at the other end with a handle. One arm is provided with a leaf spring and gauge so that upon insertion of the probe end of the test device into a pocket located between the bond lines, a sq ueezing action applied to the handles results in a movement of one handle relative to the other of an amount indicated by the gauge so as to provide a reading of the bond strength between the individual layers of the trim assembiy.

1 Claim, 6 Drawing Figures Patented July 25, 1972 3,678,738

2 Sheets-Sheet 2 A TTOR/VEV TEST DEVICE FOR TRIM ASSEMBLIES In the manufacture of decorative trim assemblies for use in the interior of automobiles, the common practice has been to provide embossed trim or bond lines in the trim sheet by utilizing a dielectric heating operation. The trim assembly usually includes a trim or cover sheet positioned on a filler material impregnated with a heat fusible plastic and supported by a fiberboard or fabric backing sheet. When this assembly is dielectrically embossed, the trim sheet is bonded to the backing sheet through the tiller material with the plastic in the latter having been melted and cured along the embossed lines and serving as the bonding adhesive. In instances where the bond lines are spaced relatively close together and in parallel relationship, a riser section is formed between the lines. This riser section when viewed in cross section, consists of an arcuate section beginning and terminating at adjacent bond lines with thetrim material therebetween being held in elevated position by the filler material. A number of such bond lines formed on the trim assembly results in a series of risers that produce an attractive decoration giving the observer the impression of a sewn assembly.

In order to maintain production quality, it is the present practice to test the bond strength between the layers of the trim assembly by physically separating the layers and measuring the force needed to obtain the separation. This force is then correlated to actual service conditions and, in this manner, the quality of the bond is determined. As should be apparent, however, this technique of determining the bond strength of the several layers of a trim assembly results in the latter being destroyed in each instance. Accordingly, there is a need to provide a test device which will determine the strength of the bond and still permit the trim assembly to be used as a finished product assuming it meets the minimum bond strength requirements.

The present invention is directed to this end and has as its primary object the provision of a portable hand-operated test device which nondestructively determines the bond strength between the individual layers of a fabricated trim assembly having a plurality of substantially parallel bond lines between each pair of which is a riser section defining a pocket. This objective is realized by a test device which in the preferred form includes a pair of overlapping arms pivotally interconnected by a pin intermediate the longitudinal depths thereof. One of the arms has a rigid probe section located at one end thereof for supporting the pin and includes a leaf spring which is connected to and extends from the probe section. Similarly, the other arm has a probe section at one end that is located alongside the other probe section so as to have a combined width which permits both probe sections to be inserted with a snug fit into the pocket formed in the trim assembly. Each of the overlapping arms terminate at the other end with an offset handle so as to provide the test device with a pair of laterally spaced handles located side by side and separated a distance which allows the handles to be grasped and squeezed toward each other to cause the probe sections to separate when unrestrained from movement. In addition, a gauge member is rigidly secured to one arm and has a portion provided with a graduated scale. A pointed member is fixed to the same arm and cooperates with the graduated scale to provide a reading and thereby indicate the bond strength between the layers of the trim assembly when the probe end of the test device is inserted into the pocket and the handles are squeezed toward each other.

Other features and advantages of the present invention will be more apparent from a reading of the following detailed description when taken with the drawings in which:

FIG. 1 is a perspective view showing a test device made according to this invention being used for determining the bond strength of a trim assembly;

FIG. 2 is a plan view showing the test device of FIG. 1;

FIG. 3 is a side elevational view of the test device of FIGS. 1 and 2;

FIG. 4 shows the test device of FIGS. 2-3 being used in a manner similar to that as shown in FIG. 1;

FIG. 5 shows the relative positions of the various parts of the test device when the bond between the cover sheet and the inner pad has failed, and

FIG. 6 is an exploded isometric view showing in detail the various parts which make up the test device of FIGS. 1-5.

Referring now to the drawings and more particularly FIGS. 1 and 5 thereof, a test device 10 made in accordance with the invention is shown being held at one end by a human hand ll, while the other end is inserted within a pocket 12 located between a pair of a plurality of substantially parallel bond lines 13 formed in a trim assembly 14. The trim assembly 14 includes a cover or trim sheet 16, a filler material (not shown) and a backing sheet 17. As is usual, the trim sheet 16 is bonded to the backing sheet 17 through the treated filler material by a dielectric embossing process as, for example, can be seen in U.S. Pat. No. 2,946,713 in the name of Dusina, Jr., et al., issued on July 26, 1960. Another disclosure showing a trim assembly made by a dielectric embossing process and having riser sections of the general type found in the trim assembly 14 can be seen in US. Pat. No. 3,265,551 in the name ofAnanian et al., issued on Aug. 19, 1966.

The test device 10, in general, comprises a pair of arms 18 and 20 arranged in overlapping relationship and pivotally interconnected in a scissors fashion by a pivot pin 22. The arms 18 and 20 terminate at one end thereof with probe sections 24 and 26, respectively, while the opposite ends of the arms are formed with outwardly curved and offset handles 28 and 30 adapted to be grasped and squeezed inwardly relative to each other as shown in FIG. 1. A gauge member 32 is secured to the arm 20 so when the probe sections 24 and 26 of the test device are inserted within the pocket 12 of the trim assembly 14, a squeezing action provides a reading which permits an observer to determine the bond strength between the layers of the trim assembly along the bond lines 13.

More specifically and as seen in FIGS. 2, 3 and 6, the arm 18 is made as a unitary member which includes the probe section 24 which has a rectangular cross-section with its major axis lying in a vertical plane. The probe section 24 is located to one side of an aperture 31 that serves to accommodate the pin 22 and is integrally formed with a flat section 34 that extends from the upper portion of the probe section 24 and terminates with the outwardly curved handle 28. The probe section 26 is also rectangular in cross-section with the major axis thereof lying in a vertical plane and has a shoe 35 removably attached thereto. The lower portion of the probe section 26 is rigidly and integrally joined to a flat section 36 having an aperture 38 formed therein for receiving the pin 22. In this case, however, a leaf spring 40 constitutes a portion of the arm body and with one end thereof secured to the flat section 36 by a pair of screws 42 and 44. The opposite end of the leaf spring 40 is secured to the handle 30 by screws 46 and 48 which extend through and rigidly support a pointer member 50 on the ban dle 30.

As seen in FIGS. 3 and 6, the gauge member 32 is secured to the underside of the arm 20 by a pair of screws 52 and 54 which respectively extend through apertures 56 and 58 formed in an elongated-body portion 60. The body portion 60 extends along the length of the leaf spring 40 and terminates with an enlarged section 62 having a graduated scale 64 formed on the upper surface thereof. A stop member 66 is integrally formed on the enlarged section 62 and serves as an abutment for the leaf spring 40 when the test device 10 is in the normal position of FIGS. 2 and 3.

In addition, an indicator member 68 is attached to the underside of the test device 10 and has one end thereof formed with an aperture 70 for connection to the flat section 36 by the pivot pin 22. The opposite end of the indicator member 68 is formed with an upstanding tongue 72 normally located above the scale 64 of the gauge member 32. A slot 74 is formed in the indicator member 68 along a curve having its center located at the center of the pivot pin 22. A screw 76 extends through the slot 74 into the flat section 36 and serves as a means for locking the indicator member 68 to the gauge member 32 or for adjusting the frictional surface contact between the top surface of the indicator member 68 and the lower surface of the gauge member 32 during relative movement therebetween.

In operating the test device 10, the various parts thereof normally assume the positions shown in FIGS. 2 and 3 prior to insertion of the probe sections into the pocket 12. In this position, the tongue 72 is rotated counterclockwise about the pivot pin 22 until it engages the side wall of the pointer member 50 which at this time provides a zero reading on the scale 64. The probe sections of the test device are then inserted into the pocket 12 of the trim assembly 14 as shown in FIGS. 1 and 4, and the handles 28 and 30 are squeezed toward each other. Because of the bond lines 13 on opposite side of the pocket 12, separating action of the probe sections 24 and 26 is prevented and, consequently, the inward force acting on the handle 30 causes the spring 40 to deflect and the handle 30 to move relative to arm 18. As the handle 30 moves relative to the arm 18, it also moves relative to the gauge member 32 which is fixed with the probe section 26 of arm 20. As a result, the pointer member 50 moves along the scale 64 and proves a visual reading of the strength of the bond along the bond lines 13. It will also be noted that as the pointer member 50 moves relative to the gauge member 32, it moves the tongue 72 of the indicator member 68 along the scale portion 64 of the gauge member 32. Assuming the required bond.strength along the bond lines 13 permits movement of the handle 30 until it reaches a predetermined reading on the scale 64 and the bond strength is less than that required, then the trim sheet 16 will tear away from the other layer of the trim assembly causing the probe sections 24 and 26 to spread apart as shown in FIG. 5. When this occurs, the straightening action of the leaf spring 40 causes the gauge member 32 to rotate clockwise with the probe section 26 about pin 22 until the stop member 66 contracts the leaf spring. It will be noted, however, that inasmuch as the tongue 72 of the indicator member 68 was carried with the pointer member 50 during the initial squeeze of the handles 28 and 30, the tongue 72 remains in the position it was moved to by the pointer member 50. As a result, it can be accurately determined at what reading the bond provided by the bond lines 13 failed.

An alternate use can also be made of the indicator member 68. For example, once the minimum required bond strength of a particular trim assembly is established, the tongue 72 can be preset at the predetermined figure on the scale 64 and the screw 76 tightened so as to prevent relative movement between the gauge member 32 and the indicator member 68. During a bond strength test as described above, the handles 28 and 30 of the test device will then be squeezed until the pointer member 50 just touches the tongue 72. Assuming the bond lines have not failed when the pointer member 50 makes contact with the tongue 72, this will indicate that the trim assembly passes the test and meets the predetermined bond strength requirements without destroying the trim assembly.

Finally, it will be noted that within certain limits, the combined width of the probe sections 24 and 26 can be varied by either removing shoe 35 or attaching a shoe of a different size to the probe section 26. Thus, in cases where the distance between the bond lines 13 is less than that of the trim assembly 14, the shoe 35 can be replaced by a shoe of less width in order to permit insertion of the probe end of the test device 10 into the accommodating pocket. In contradistinction, if the distance between the bond lines 13 is greater, the shoe 35 would be replaced by a shoe of a greater width. Moreover, although the test procedure described above has the probe end of the test device 10 entering the pocket 12 with the handles 28 and 30 lying substantially in the plane of the trim assembly 14, it should be apparent that the device can be utilized equally as well with the handles located in a plane substantially normal to the plane of the trim assembly. The latter manner of positioning the device may in many instances be the preferred manner of using this test device.

Various changes and modifications can be made in this construction without departing from the spirit of the invention. Such changes and modifications are contemplated by the inventor and he does not wish to be limited except by the scope of the appended claims,

I claim:

1. A hand-operated test device for nondestructively determining the bond strength between individual layers of a fabricated trim assembly having a plurality of substantially parallel bonded lines between each pair of which is a riser section provided with a pocket, said test device comprising first and second arms pivotally interconnected by a pin intermediate the longitudinal lengths thereof, said first arm having a rigid probe section at one end thereof, said second arm having a probe section at one end thereof located alongside the probe section of said first arm and having a combined width which permits both probe sections to be inserted with a snug fit into said pocket, each of said arms terminating at the other end with an offset handle so as to provide the test device with a pair of laterally spaced handles located side by side and separated a distance that permits a single hand to squeeze both handles toward each other and cause the probe sections to separate when unrestrained, a leaf spring having the opposite ends thereof interconnecting said probe section of said first arm with the handle thereof and serving as the sole sup port for said handle to permit relative movement of both of the handles when the latter are squeezed and the probe sections are restrained from movement, a gauge member rigidly secured to said probe section of said first arm and having a portion provided with a graduated scale located adjacent the handle of said first arm, a pointer member fixed to the handle of the first arm and cooperating with said graduated scale to provide a reading and thereby indicate the bond strength between said layers when said probe sections are inserted into said pocket and the handles are squeezed toward each other, an indicator member pivotally attached to said first arm and movable along the scale on said gauge member, and means carried by said first arm for locking said indicator member in a predetermined position relative to said gauge member for indicating the maximum amount that the handles should be squeezed towards each other during a bond strength test of the trim assembly.

Claims (1)

1. A hand-operated test device for nondestructively determining the bond strength between individual layers of a fabricated trim assembly having a plurality of substantially parallel bonded lines between each pair of which is a riser section provided with a pocket, said test device comprising first and second arms pivotally interconnected by a pin intermediate the longitudinal lengths thereof, said first arm having a rigid probe section at one end thereof, said second arm having a probe section at one end thereof located alongside the probe section of said first arm and having a combined width which permits both probe sections to be inserted with a snug fit into said pocket, each of said arms terminating at the other end with an offset handle so as to provide the test device with a pair of laterally spaced handles located side by side and separated a distance that permits a single hand to squeeze both handles toward each other and cause the probe sections to separate when unrestrained, a leaf spring having the opposite ends thereof interconnecting said probe section of said first arm with the handle thereof and serving as the sole support for said handle to permit relative movement of both of the handles when the latter are squeezed and the probe sections are restrained from movement, a gauge member rigidly secured to said probe section of said first arm and having a portion provided with a graduated scale located adjacent the handle of said first arm, a pointer member fixed to the handle of the first arm and cooperating with said graduated scAle to provide a reading and thereby indicate the bond strength between said layers when said probe sections are inserted into said pocket and the handles are squeezed toward each other, an indicator member pivotally attached to said first arm and movable along the scale on said gauge member, and means carried by said first arm for locking said indicator member in a predetermined position relative to said gauge member for indicating the maximum amount that the handles should be squeezed towards each other during a bond strength test of the trim assembly.

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