<Page>

                                                                     EXHIBIT 3.7

                                                                          [SEAL]

                          CERTIFICATE OF INCORPORATION

                                       OF

                           WINFRED BERG LICENSCO INC.

          FIRST: The name of the corporation is WINFRED BERG LICENSCO INC. (the
"Corporation").

          SECOND: The address of its registered office in the State of Delaware
is 1209 Orange Street, in the County of New Castle, Wilmington, Delaware, and
the name of its registered agent at such address is The Corporation Trust
Company.

          THIRD: The nature of the business or purposes to be conducted or
promoted are:

          To engage in any lawful act or activity for which corporations may be
organized under the General Corporation Law of the State of Delaware; and

          In general, to possess and exercise all the powers and privileges
granted by the General Corporation Law of the State of Delaware or by any other
law of Delaware or by this certificate of incorporation, together with any
powers incidental thereto, so far as such powers and privileges are necessary or
convenient to the conduct, promotion or attainment of the business or purposes
of the Corporation.

          FOURTH: The total number of shares of stock which the Corporation
shall have authority to issue is one thousand


<Page>

                                                                               2

(1,000) shares of Common Stock, par value $.01 per share, amounting in the
aggregate to one hundred dollars ($100).

          FIFTH: The name and mailing address of the incorporator is Mary Jo
Cisternino, c/o Cummings & Lockwood, Ten Stamford Forum, P.O. Box 120,
Stamford, Connecticut 06904.

          SIXTH: The Board of Directors is expressly authorized to exercise
all powers granted to the directors by law except insofar as such powers are
limited or denied herein or in the By-Laws of the Corporation. In furtherance
of such powers, the Board of Directors shall have the right to make, alter or
repeal the By-Laws of the Corporation.

          SEVENTH: Meetings of stockholders may be held within or without the
State of Delaware, as the By-Laws may provide. The books of the Corporation
may be kept (subject to any provision contained in the statutes) outside the
State of Delaware at such place or places as may be designated from time to
time by the Board of Directors or in the By-Laws of the Corporation.
Elections of directors need not be by written ballot unless the By-Laws of
the Corporation shall so provide.

          EIGHTH: Whenever a compromise or arrangement is proposed between the
Corporation and its creditors or any class of them and/or between the
Corporation and its stockholders or any class of them, any court of equitable


<Page>

                                                                               3

jurisdiction within the State of Delaware may, on the application in a summary
way of the Corporation or of any creditor or stockholder thereof or on the
application of any receiver or receivers appointed for the Corporation under the
provisions of Section 291 of Title 8 of the Delaware Code or on the application
of trustees in dissolution or of any receiver or receivers appointed for the
Corporation under the provisions of Section 279 of Title 8 of the Delaware Code,
order a meeting of the creditors or class of creditors, and/or of the
stockholders or class of stockholders of the Corporation, as the case may be, to
be summoned in such a manner as the said court directs. If a majority in number
representing three-fourths in value of the creditors or class of creditors,
and/or of the stockholders or class of stockholders of the Corporation, as the
case may be, agree to any compromise or arrangement and to any reorganization of
the Corporation as a consequence of such compromise or arrangement, the said
compromise or arrangement and the said reorganization shall, if sanctioned by
the court to which the said application is made, be binding upon all of the
creditors or class of creditors, and/or on all the stockholders or class of
stockholders, of the Corporation, as the case may be, and also on the
Corporation.

<Page>

                                                                               4

          NINTH: No director shall have any personal liability to the
Corporation or its stockholders for any monetary damages for breach of fiduciary
duty as a director, except that this Article shall not eliminate or limit the
liability of each director (i) for any breach of such director's duty of loyalty
to the Corporation or its stockholder, (ii) for acts or omissions not in good
faith or which involve intentional misconduct or a knowing violation of law,
(iii) under Section 174 of the Delaware General Corporation Law, or (iv) for any
transaction from which such director derived an improper personal benefit.

          TENTH: The Corporation reserves the right to amend, alter, change or
repeal any provision contained in this certificate of incorporation in the
manner now or hereafter prescribed by statute.

          THE UNDERSIGNED, being the sole incorporator hereinbefore named, for
the purpose of forming a corporation pursuant to the General Corporation Law of
the State of Delaware, makes this certificate, hereby declaring and certifying
that this is her act and deed and the facts herein stated are true, and
accordingly, has hereunto set her hand this 29th day of November, 1988.


                                    /s/ Mary Jo Cisternino
                                    --------------------------
                                    Mary Jo Cisternino
                                    Sole Incorporator